DayCent 4.5 is built from the monthly version of Century and for the most part

the *.100 parameter files used by DayCent 4.5 are identical to the ones used

by Century 4.5.  There are a few input parameters that need to be scaled to

work with the smaller time step used in DayCent as compared to monthly

Century.

    CROP.100

    CULT.100

    FERT.100

    FIRE.100

    FIX.100    - some changes to this file, see notes below

    GRAZ.100

    HARV.100

    IRRI.100

    OMAD.100

    TREE.100

    TREM.100

    <site>.100 - some changes to this file, see notes below

    *.sch (schedule files)



Additional input files used by DayCent are:

    SOILS.IN    - a description of the soil layer structure

    SITEPAR.IN  - additional site information needed by DayCent

    OUTFILES.IN - allows the user to select which weekly and/or daily ASCII

                  output files will be created by DayCent



DayCent must be run using a daily weather data file.



------------------------------------------------------------------------------

FIX.100 modifications for DayCent:



When modifying the FIX.100 file for use with DayCent the following settings

are recommended:

    ADEP(1)   = 10.0

    ADEP(2)   = 20.0

    ADEP(3)   = 15.0

    ADEP(4)   = 15.0

    ADEP(5)   = 30.0

    ADEP(6)   = 30.0

    ADEP(7)   = 30.0

    ADEP(8)   = 30.0

    ADEP(9)   = 30.0

    ADEP(10)  = 30.0

    FWLOSS(1) = 1.0

    FWLOSS(2) = 1.0

    FWLOSS(3) = 1.0

    FWLOSS(4) Is not used when extra drivers are used.  The extra drivers are

              the solar radiation, relative humidity, and wind speed input

              parameters in the daily weather file.  If not using the extra

              drivers set this value to 0.8.

    ANEREF(3) = 1.0

    OMLECH(3) < 2.0

    MINLCH    to approximately 2.5

    VLOSSE    = 0.0

    VLOSSG    = 0.0

    IDEF      = 1.0



------------------------------------------------------------------------------

<site>.100 modifications for DayCent:

 

When modifying the <site>.100 file for use with DayCent set the SWFLAG and

STORMF parameters to 0.0.

     SWFLAG = 0.0

     STORMF = 0.0



Also, if you are modifying a <site>.100 file that was used for running monthly

Century version 4.0 you will need to remove the following parameters from the

<site>.100 file:

     W1LIG

     W2LIG

     W3LIG

as they are not used by DayCent.



The values of SAND, SILT, CLAY, BULKD, PH, AWILT, and AFIEL in the <site>.100

file are overridden by their companion values in the SOILS.IN input file.



NOTE:

DayCent does use the weather statistics from the <site>.100 file.  The monthly

average precipitation values are used in the atmospheric nitrogen deposition

function.  The average minimum and maximum temperature values are used to

replace missing temperature values in a daily weather data file.  Prior to

running a DayCent simulation be sure to use the DayCent_file100 utility to

create weather statisitics for your <site>.100 file based on your daily

historical weather data file.



------------------------------------------------------------------------------

Schedule file notes for running DayCent:



When creating your schedule file for DayCent keep in mind that it operates

using daily weather data and must be able to find and read your daily weather

data file.  The "F" weather option choice is the only valid weather option for

the initial block in a DayCent schedule file.  The weather filename of the

daily weather data file must also appear in your schedule file following the

"F".  If you use a weather option value other than "F" for the initial weather

option in your schedule file the simulation will not run.  Subsequent blocks

may use either the "F", to start reading from the start of a daily weather

file, or "C", to continue reading the current weather file, weather options.



==============================================================================

SOILS.IN example:



  0.0   2.0  1.44  0.31092  0.13578  0.80  0.01  0.39  0.28  0.01  0.11  0.00027  5.00

  2.0   5.0  1.44  0.31092  0.13578  0.20  0.04  0.39  0.28  0.01  0.08  0.00027  5.00

  5.0  10.0  1.44  0.31092  0.13578  0.00  0.25  0.39  0.28  0.01  0.05  0.00027  5.00

 10.0  20.0  1.44  0.31092  0.13578  0.00  0.30  0.39  0.28  0.01  0.01  0.00027  5.00

 20.0  30.0  1.44  0.31092  0.13578  0.00  0.10  0.39  0.28  0.01  0.00  0.00027  5.00

 30.0  45.0  1.44  0.31092  0.13578  0.00  0.05  0.39  0.28  0.01  0.00  0.00027  5.00

 45.0  60.0  1.44  0.31092  0.13578  0.00  0.04  0.39  0.28  0.01  0.00  0.00027  5.00

 60.0  75.0  1.44  0.31092  0.13578  0.00  0.03  0.39  0.28  0.01  0.00  0.00027  5.00

 75.0  90.0  1.44  0.31092  0.13578  0.00  0.02  0.39  0.28  0.01  0.00  0.00027  5.00

 90.0 105.0  1.44  0.31092  0.13578  0.00  0.01  0.39  0.28  0.01  0.00  0.00027  5.00

105.0 120.0  1.44  0.31092  0.13578  0.00  0.00  0.39  0.28  0.01  0.00  0.00027  5.00

120.0 150.0  1.44  0.31092  0.13578  0.00  0.00  0.39  0.28  0.01  0.00  0.00027  5.00



Column  1 - Minimum depth of soil layer (cm)

Column  2 - Maximum depth of soil layer (cm)

Column  3 - Bulk density of soil layer (g/cm^3)

Column  4 - Field capacity of soil layer, volumetric

Column  5 - Wilting point of soil layer, volumetric

Column  6 - Evaporation coefficient for soil layer (currently not being used)

Column  7 - Percentage of roots in soil layer, these values must sum to 1.0

Column  8 - Fraction of sand in soil layer, 0.0 - 1.0

Column  9 - Fraction of clay in soil layer, 0.0 - 1.0

Column 10 - Organic matter in soil layer, fraction 0.0 - 1.0

Column 11 - Minimum volumetric soil water content below wilting point for soil

            layer, soil water content will not be allowed to drop below this

            value

Column 12 - Saturated hydraulic conductivity of soil layer in centimeters per

            second

Column 13 - pH of soil layer



NOTES:

Percentage of silt for soil layer is computed as follows:

     percent silt = (1.0 - (percent sand + percent clay))



For the trace gas subroutines it is currently recommended to use the following

layering structure for the top 3 soil layers in your soils.in file:

     layer 1 - 0.0 cm to  2.0 cm

     layer 2 - 2.0 cm to  5.0 cm

     layer 3 - 5.0 cm to 10.0 cm



The depth structure in this file should match the ADEP values in the FIX.100

file in such a way that the boundaries for the soil layer depths can be

matched with the ADEP values.  For example, using the file above and ADEP

values of 10, 20, 15, 15, 30, 30, 30, 30, 30, and 30:

     layers 1, 2 and 3 match the first 10 centimeter ADEP value

     layers 4 and 5 match the second 20 centimeter ADEP value

     layer 6 matches the third 15 centimeter ADEP value

     layer 7 matches the fourth 15 centimeter ADEP value

     layers 8 and 9 match the first 30 centimeter ADEP value

     layers 10 and 11 match the second 30 centimeter ADEP value

     layer 12 matches the third 30 centimeter ADEP value



The value for NLAYER in the <site>.100 file should be set to match the number

of ADEP values that you are using when you match the layering to the soils.in

file.  For the example above NLAYER should be set to 7.



==============================================================================

SITEPAR.IN example:



2        / timstep: 1=monthly production, 2=weekly production

0        / 1 = Use extra weather drivers (solrad, rhumid, windsp), 0 = don't use (for PET)

1.0      / sublimscale

0.18     / reflec - vegetation reflectivity/albedo (frac)

0.65     / albedo - snow albedo (frac)

0.90     / fswcinit - initial swc, fraction of field capacity

0.000001 / dmpflux - in h2oflux routine (0.000001 = original value)

4        / hours_rain - duration of each rain event

0        / # of days between rainfall event and drainage of soil (-1=computed)

1  0     / watertable[month] - 0 = no water table, 1 = water table

2  0

3  0

4  0

5  0

6  0

7  0

8  0

9  0

10 0

11 0

12 0

-200     / hpotdeep - hydraulic water potential of deep storage layer (units?)

0.0002   / ksatdeep - saturated hydraulic conductivity of deep storage layer (cm/sec)

1  58    / cldcov[month] - cloud cover (%)

2  58

3  58

4  58

5  58

6  58

7  58

8  58

9  58

10 58

11 58

12 58

5.0 16.4 / min and max temperature for bottom soil layer (degrees C)

0.003    / damping factor for calculating soil temperature by layer

30.0     / timlag, days from Jan 1 to coolest temp at bottom of soil (days)

0.03     / min water/temperature limitation coefficient for nitrify

50 90    / turn off respiration restraint on denit between these days

0.8      / nitrification N2O adjustment factor (0.0-1.0)



NOTES:

Values in this file that should normally not be changed:

     timstep     - 1 = monthly production, 2 = weekly production

     sublimscale - scaling multiplier for sublimation

     dmpflux     - damping factor for soil water flux, in h2oflux routine

     hours_rain  - duration of each rain event



If modifying the hours_rain parameter value be aware that the smallest valid

value for the hours_rain parameter is 2.0.  Valid values for hours_rain must

be a multiple of 2 and may not exceed 24.



==============================================================================

OUTFILES.IN example:



Output (0/1)  file_name         description

0             bio.out           # weekly above and below ground live carbon

0             soiln.out         # daily soil ammonium and nitrate by layer

0             soiltavg.out      # daily average soil temperature by layer

0             soiltmax.out      # daily maximum soil temperature by layer

0             soiltmin.out      # daily minimum soil temperature by layer

0             stemp_dx.out      # daily soil temperature every few cm (HUGE)!

0             vswc.out          # daily volumetric soilwater content by layer

0             watrbal.out       # daily water balance

0             wfps.out          # daily water filled pore space by layer

0             co2.out           # daily CO2 concentrations by layer

1             wflux.out         # daily water flux through the bottom of soil layers

0             mresp.out         # weekly maintenance respiration

0             year_summary.out  # yearly sums of N2Oflux, NOflux and CH4

1             livec.out         # weekly live carbon

1             deadc.out         # weekly dead carbon

1             soilc.out         # weekly soil carbon

0             sysc.out          # weekly system carbon

1             tgmonth.out       # monthly trace gas fluxes

1             dN2lyr.out        # daily denitrification N2 fluxes by layer

1             dN2Olyr.out       # daily denitrification N2O fluxes by layer



NOTES:

0 = do not produce the output file

1 = do produce the output file



The DAILY.OUT, NFLUX.OUT and SUMMARY.OUT files are always produced when

running DayCent therefore they are not included in the outfiles.in file.



==============================================================================

Daily Weather Data File:



 1   1  1990    1    7.040  -10.300    0.000  186.425   55.42   10.939

 2   1  1990    2    9.200  -10.530    0.000  158.115   57.42    5.552

 3   1  1990    3   11.840   -7.330    0.000  222.946   42.13    9.165

 4   1  1990    4    1.297  -10.310    0.000  182.844   40.97   12.543

 5   1  1990    5    1.239  -16.010    0.000  213.159   52.25    5.214

 6   1  1990    6    3.745   -9.380    0.000  230.346   41.89   10.603

...

27  12  1992  362   11.320  -12.880    0.000  217.456   35.13    4.429

28  12  1992  363    7.050  -10.180    0.000  216.501   28.25    5.132

29  12  1992  364   -1.095   -8.370    0.000   93.833   53.59    5.264

30  12  1992  365    7.330  -11.490    0.000  152.243   35.88    3.098

31  12  1992  366    7.330  -11.490    0.000  152.243   35.88    3.098



NOTES:

Column  1 - Day of month, 1-31

Column  2 - Month of year, 1-12

Column  3 - Year

Column  4 - Day of the year, 1-366

Column  5 - Maximum temperature for day, degrees C

Column  6 - Minimum temperature for day, degrees C

Column  7 - Precipitation for day, centimeters

Column  8 - Solar radiation, in langleys/day

Column  9 - Relative humidity, percentage, 1-100

Column 10 - Wind speed, miles per hour



Missing weather data values for precipitation, minimum temperature and maximum

temperature are represented by the value -99.9.



The last three columns in the weather data file, solar radiation, relative

humidity, and wind speed, are optional.  When these values are not included in

a weather file PET is computed using the FWLOSS(4) input variable from the

FIX.100 file and the flag for the extra weather drivers in the SITEPAR.IN file

must be set to 0.



==============================================================================

Time representation in output files:



DayCent ASCII output files are produced in addition to the monthly output in

the *.bin file.  Simulation time in the DayCent output file is represented as

a decimal value with the value preceding the decimal point representing the

year of the simulation and the value after the decimal point representing the

month in the simulation using the following values:

     Jan - .00

     Feb - .08

     Mar - .17

     Apr - .25

     May - .33

     Jun - .42

     Jul - .50

     Aug - .58

     Sep - .67

     Oct - .75

     Nov - .83

     Dec - .92



The *.bin file that is produced when using DayCent contains monthly output

values.  Simulation times for the monthly output from the *.bin file are

represented as a decimal value with the value preceding the decimal point

representing the year of the simulation and the value after the decimal point

representing the month in the simulation using the following values:

     Jan - .08

     Feb - .17

     Mar - .25

     Apr - .33

     May - .42

     Jun - .50

     Jul - .58

     Aug - .67

     Sep - .75

     Oct - .83

     Nov - .92

     Dec - 1.00

These month fractions are added to the year value so that, for example January

of year 1998 will output as time 1998.08 (1998 + .08) and December of year

1998 will output as time 1999.00 (1999 + 1.00).



Note that the monthly time values in the *.bin files are shifted by 1/12 from

the DayCent ASCII *.out output files such that:



          *.out file                *.bin file

          ----------                ----------

           Jan - .00                Jan -  .08

           Feb - .08                Feb -  .17

           Mar - .17                Mar -  .25

           Apr - .25                Apr -  .33

           May - .33                May -  .42

           Jun - .42                Jun -  .50

           Jul - .50                Jul -  .58

           Aug - .58                Aug -  .67

           Sep - .67                Sep -  .75

           Oct - .70                Oct -  .83

           Nov - .83                Nov -  .92

           Dec - .92                Dec - 1.00



==============================================================================

BIOWK.OUT (weekly above and below ground live carbon):



  time  wk      aglivc      bglivc      aglivn      bglivn      rleavc      frootc      fbrchc      rlwodc      crootc

1895.00   1     20.0516    127.4018      0.7884      1.9148      0.9462      0.5855      0.0000      0.0000      0.0000



Column 1  - Simulation time (see above)

Column 2  - Week of the month, 1 - 5

Column 3  - Carbon in aboveground live for grass/crop (gC/m^2)

Column 4  - Carbon in belowground live for grass/crop (gC/m^2)

Column 5  - Nitrogen in aboveground live for grass/crop (gN/m^2)

Column 6  - Nitrogen in belowground live for grass/crop (gN/m^2)

Column 7  - Carbon in forest system leaf compenent (gC/m^2)

Column 8  - Carbon in forest system fine root component (gC/m^2)

Column 9  - Carbon in forest system fine branch component (gC/m^2)

Column 10 - Carbon in forest system large wood component (gC/m^2)

Column 11 - Carbon in forest system coarse root component (gC/m^2)



==============================================================================

CO2.OUT (daily CO2 concentrations by layer):



    time  jday    CO2_ppm[0]    CO2_ppm[1]    CO2_ppm[2]    CO2_ppm[3]    CO2_ppm[4]    CO2_ppm[5]    CO2_ppm[6]    CO2_ppm[7]    CO2_ppm[8]    CO2_ppm[9]        etc...

 1895.00     1      1.461087      1.200228      0.624179      0.345650      0.104632      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000  



Column 1   - Simulation time (see above)

Column 2   - Day of the year

Column 3   - CO2 concentration in first layer of soil profile (index 0), as

             defined in the soils.in file (ppm)

Column 4   - CO2 concentration in second layer of soil profile (index 1), as

             defined in the soils.in file (ppm)

...

Column n+2 - CO2 concentration in layer n of the soil profile (index n-1), as

             defined in the soils.in file (ppm)



NOTE:

n = number of soil layers



==============================================================================

DAILY.OUT:



      time jday      PET(cm)      agdefac      bgdefac     stemp(C)    snow    snlq   thermunits

 1995.0000    1        .0319        .0979        .0845      -5.0299   .0000  .0000        .0000



Column 1 - Simulation time (see above)

Column 2 - Day of the year

Column 3 - Potential evapotranspiration rate for the day (cm H2O)

Column 4 - Surface decomposition factor based on temperature and moisture

Column 5 - Soil decomposition factor based on temperature and moisture

Column 6 - Average soil temperature near the soil surface (degrees C)

Column 7 - Snowpack water content (cm H2O)

Column 8 - Liquid snow water content (cm H2O)

Column 9 - accumulator of thermal units for growing degree day implementation



==============================================================================

DEADCWK.OUT (weekly carbon in dead plant material):



  time  wk      stdedc   metabc(1)   strucc(1)      wood1c      wood2c      wood3c

1895.00   1     17.7980      9.8971     38.7231      0.0000      0.0000      0.0000



Column 1 - Simulation time (see above)

Column 2 - Week of the month, 1 - 5

Column 3 - C in standing dead material for grass/crop (gC/m^2)

Column 4 - metabolic C in surface litter (gC/m^2)

Column 5 - surface litter structrual C (gC/m^2)

Column 6 - C in wood1 (dead fine branch) component of forest system (gC/m^2)

Column 7 - C in wood2 (dead large wood) component of forest system (gC/m^2)

Column 8 - C in wood3 (dead coarse roots) component of forest system (gC/m^2)



==============================================================================

DN2LYR.OUT (daily N2 fluxes due to denitrification by layer):



    time  jday   dN2_g/m2[0]   dN2_g/m2[1]   dN2_g/m2[2]   dN2_g/m2[3]   dN2_g/m2[4]   dN2_g/m2[5]   dN2_g/m2[6]   dN2_g/m2[7]   dN2_g/m2[8]   dN2_g/m2[9]        etc...

 1995.00     1      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000  



Column 1   - Simulation time (see above)

Column 2   - Day of the year (1..366)

Column 3   - N2 flux from the first layer of soil profile (index 0), as

             defined in the soils.in file (gN/m^2)

Column 4   - N2 flux from the second layer of soil profile (index 0), as

             defined in the soils.in file (gN/m^2)

...

Column n+2 - N2 flux from the layer n of soil profile (index 0), as defined in

             the soils.in file (gN/m^2)



NOTE:

n = number of soil layers



==============================================================================

DN2OLYR.OUT (daily N2O fluxes due to denitrification by layer):



    time  jday  dN2O_g/m2[0]  dN2O_g/m2[1]  dN2O_g/m2[2]  dN2O_g/m2[3]  dN2O_g/m2[4]  dN2O_g/m2[5]  dN2O_g/m2[6]  dN2O_g/m2[7]  dN2O_g/m2[8]  dN2O_g/m2[9]        etc...

 1995.00     1      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000      0.000000  



Column 1   - Simulation time (see above)

Column 2   - Day of the year (1..366)

Column 3   - N2O flux from the first layer of soil profile (index 0), as

             defined in the soils.in file (gN/m^2)

Column 4   - N2O flux from the second layer of soil profile (index 0), as

             defined in the soils.in file (gN/m^2)

...

Column n+2 - N2O flux from the layer n of soil profile (index 0), as defined in

             the soils.in file (gN/m^2)



NOTE:

n = number of soil layers



==============================================================================

LIVECWK.OUT (weekly carbon in live plant material):



  time  wk      aglivc      bglivc      rleavc      frootc      fbrchc      rlwodc      crootc

1895.00   1     20.0516    127.4018      0.9462      0.5855      0.0000      0.0000      0.0000



Column 1 - Simulation time (see above)

Column 2 - Week of the month, 1 - 5

Column 3 - C in aboveground live for grass/crop (gC/m^2)

Column 4 - C in belowground live for grass/crop (gC/m^2)

Column 5 - C in forest system leaf component (gC/m^2)

Column 6 - C in forest system fine root component (gC/m^2)

Column 7 - C in forest system fine branch component (gC/m^2)

Column 8 - C in forest system large wood component (gC/m^2)

Column 9 - C in forest system coarse root component (gC/m^2)



==============================================================================

MRESP.OUT (maintenance respiration):



  time   wk   mrspflow(1)   mrspflow(2)  cmrspflux(1)  crmspflux(2)  fmrspflux(1)  fmrspflux(2)  fmrspflux(3)  fmrspflux(4)  fmrspflux(5)      mcprd(1)      mcprd(2)      mfprd(1)      mfprd(2)      mfprd(3)      mfprd(4)      mfprd(5)  mrspstg(1,1)  mrspstg(1,2)  mrspstg(2,1)  mrspstg(2,2)    mrspann(1)    mrspann(2)

1895.00   1        0.0621        0.0000        0.0147        0.0936        0.0030        0.0012        0.0000        0.0000        0.0000        0.0982        0.2121        0.0000        0.0000        0.0000        0.0000        0.0000       17.6574        0.0000        4.9443        0.0000        0.1083        0.0000



Column 1  - Simulation time (see above)

Column 2  - Week of the month, 1 - 5

Column 3  - weekly maintenance respiration flow to storage pool (mrspstg(1,*)

            from C source/sink for grass/crop system (gC/m^2)

Column 4  - weekly maintenance respiration flow to storage pool (mrspstg(2,*)

            from C source/sink for tree system (gC/m^2)

Column 5  - amount of weekly maintenance respiration flux from aboveground

            grass/crop material that flows from the grass/crop maintenance

            respiration storage pool (mrspstg(1,*)) to the C source/sink pool

            (csrsnk) (gC/m^2)

Column 6  - amount of weekly maintenance respiration flux from belowground

            grass/crop material that flows from the grass/crop maintenance

            respiration storage pool (mrspstg(1,*)) to the C source/sink pool

            (csrsnk) (gC/m^2)

Column 7  - amount of weekly maintenance respiration flux from live leaf

            material that flows from the tree maintenance respiration storage

            pool (mrspstg(2,*)) to the C source/sink pool (csrsnk) (gC/m^2)

Column 8  - amount of weekly maintenance respiration flux from live fine root

            material that flows from the tree maintenance respiration storage

            pool (mrspstg(2,*)) to the C source/sink pool (csrsnk) (gC/m^2)

Column 9  - amount of weekly maintenance respiration flux from live fine

            branch material that flows from the tree maintenance respiration

            storage pool (mrspstg(2,*)) to the C source/sink pool (csrsnk)

            (gC/m^2)

Column 10 - amount of weekly maintenance respiration flux from live large wood

            material that flows from the tree maintenance respiration storage

            pool (mrspstg(2,*)) to the C source/sink pool (csrsnk) (gC/m^2)

Column 11 - amount of weekly maintenance respiration flux from live coarse

            material that flows from the tree maintenance respiration storage

            pool (mrspstg(2,*)) to the C source/sink pool (csrsnk) (gC/m^2)

Column 12 - weekly NPP for shoots for grass/crop system (gC/m^2)

Column 13 - weekly NPP for roots for grass/crop system (gC/m^2)

Column 14 - weekly NPP for live leaves for tree system (gC/m^2)

Column 15 - weekly NPP for live fine roots for tree system (gC/m^2)

Column 16 - weekly NPP for live fine branches for tree system (gC/m^2)

Column 17 - weekly NPP for live large wood for tree system (gC/m^2)

Column 18 - weekly NPP for live coarse roots for tree system (gC/m^2)

Column 19 - unlabeled C in maintenance respiration storage for grass/crop

            system (gC/m^2)

Column 20 - labeled C in maintenance respiration storage for grass/crop system

            (gC/m^2)

Column 21 - unlabeled C in maintenance respiration storage for forest system

            (gC/m^2)

Column 22 - labeled C in maintenance respiration storage for forest system

            (gC/m^2)

Column 23 - accumulator for annual maintenance respiration for grass/crop

            (gC/m^2)

Column 24 - accumulator for annual maintenance respiration for tree (gC/m^2)



==============================================================================

NFLUX.OUT (trace gases):



      time jday    nit_N2O-N   dnit_N2O-N    dnit_N2-N         NO-N   CUM-N2O(gN/ha) CUM-NO(gN/ha

 1895.0000    1        .0037        .2862        .3268       2.6953            .2899       2.6953



Column 1 - Simulation time (see above)

Column 2 - Day of the year

Column 3 - Nitrous oxide nitrification (gN/ha)

Column 4 - Nitrous oxide denitrification (gN/ha)

Column 5 - Elemental inert nitrogen gas denitrification (gN/ha)

Column 6 - Nitric oxide (gN/ha)

Column 7 - Annual accumulator for nitrous oxide (gN/ha)

Column 8 - Annual accumulator for nitric oxide (gN/ha)



==============================================================================

SOILCWK.OUT (weekly carbon in soil organic matter pools):



  time  wk   metabc(2)   strucc(2)    som1c(1)    som1c(2)       som2c       som3c

1895.00   1     19.1677    161.0758      9.2931     65.3974   1296.3390   1015.3623



Column 1 - Simulation time (see above)

Column 2 - Week of the month, 1 - 5

Column 3 - metabolic C in soil litter (gC/m^2)

Column 4 - soil litter structural C (gC/m^2)

Column 5 - C in surface active pool soil organic matter (gC/m^2)

Column 6 - C in soil active soil pool organic matter (gC/m^2)

Column 7 - C in slow pool soil organic matter (gC/m^2)

Column 8 - C in passive pool soil organic matter (gC/m^2)



==============================================================================

SOILN.OUT (daily soil ammonium and nitrate by layer):



    time  jday      ammonium    NO3_ppm[0]    NO3_ppm[1]    NO3_ppm[2]    NO3_ppm[3]    NO3_ppm[4]    NO3_ppm[5]    NO3_ppm[6]    NO3_ppm[7]    NO3_ppm[8]    NO3_ppm[9]        etc...

 1895.00     1      0.882302      0.127008      0.142134      0.167252      0.010356      0.000954      0.000188      0.000042      0.000009      0.000002      0.000000      0.000000  



Column   1 - Simulation time (see above)

Column   2 - Day of the year

Column   3 - Soil ammonium in top 15 centimeters of soil (ppm)

Column   4 - Nitrate in soil layer 1 (index 0) of the soil profile, as defined

             in the soils.in file (ppm)

Column   5 - Nitrate in soil layer 2 (index 1) of the soil profile, as defined

             in the soils.in file (ppm)

...

Column n+3 - Nitrate in soil layer n (index n-1) of the soil profile, as

             defined in the soils.in file (ppm)



NOTE:

n = number of soil layers defined in soils.in file



==============================================================================

SOILTAVG.OUT (daily average soil temperature by layer):



1895.0000     1   -1.94   -2.51    1.01    7.61   11.41   12.75   12.89   12.67   12.46   12.15   10.17  

1895.0000     2    1.36   -0.92    1.23    7.51   11.35   12.71   12.88   12.67   12.46   12.14   10.12  



Column   1 - Simulation time (see above)

Column   2 - Day of the year

Column   3 - Average soil temperature for soil layer 1, as defined in soils.in

             file (degrees C)

Column   4 - Average soil temperature for soil layer 2, as defined in soils.in

             file (degrees C)

...

Column n+2 - Average soil temperature for soil layer n, as defined in soils.in

             file (degrees C)



NOTE:

n = number of soil layers defined in soils.in file



==============================================================================

SOILTMAX.OUT (daily maximum soil temperature by layer):



1895.0000     1    5.25    2.80    2.83    7.86   11.44   12.75   12.89   12.67   12.46   12.15   10.17  

1895.0000     2    7.06    3.28    2.68    7.71   11.37   12.72   12.88   12.67   12.46   12.14   10.12  



Column   1 - Simulation time (see above)

Column   2 - Day of the year

Column   3 - Maximum soil temperature for soil layer 1, as defined in soils.in

             file (degrees C)

Column   4 - Maximum soil temperature for soil layer 2, as defined in soils.in

             file (degrees C)

...

Column n+2 - Maximum soil temperature for soil layer n, as defined in soils.in

             file (degrees C)



NOTE:

n = number of soil layers defined in soils.in file



==============================================================================

SOILTMIN.OUT (daily minimum soil temperature by layer):



1895.0000     1   -9.14   -7.81   -0.82    7.36   11.39   12.75   12.89   12.67   12.46   12.15   10.17  

1895.0000     2   -4.34   -5.13   -0.21    7.31   11.33   12.71   12.88   12.67   12.46   12.14   10.12  



Column   1 - Simulation time (see above)

Column   2 - Day of the year

Column   3 - Minimum soil temperature for soil layer 1, as defined in soils.in

             file (degrees C)

Column   4 - Minimum soil temperature for soil layer 2, as defined in soils.in

             file (degrees C)

...

Column n+2 - Minimum soil temperature for soil layer n, as defined in soils.in

             file (degrees C)



NOTE:

n = number of soil layers defined in soils.in file



==============================================================================

STEMP_DX.OUT (daily soil temperature every few cm):



1895.0000     1   -1.94   -2.69   -1.71   -0.54    0.70    1.94    3.12    4.23    5.25    6.19    7.04    7.81    8.50    9.12    9.67   10.17   10.61   11.00   11.34   11.64   11.89   12.12   12.30   12.46   12.59   12.69   12.77   12.83   12.87   12.90   12.91   12.91   12.91   12.89   12.87   12.85   12.82   12.79   12.75   12.72   12.69   12.66   12.63   12.60   12.57   12.54   12.52   12.49   12.46   12.44   12.41   12.38   12.34   12.30   12.26   12.20   12.14   12.06   11.97   11.86   11.74   11.59   11.42  

1895.0000     2    1.36   -1.69   -1.01   -0.09    0.96    2.06    3.15    4.20    5.18    6.10    6.94    7.70    8.40    9.02    9.58   10.08   10.53   10.92   11.27   11.57   11.84   12.06   12.25   12.41   12.54   12.65   12.73   12.80   12.84   12.87   12.89   12.90   12.89   12.88   12.86   12.84   12.81   12.78   12.75   12.72   12.69   12.66   12.63   12.60   12.57   12.54   12.52   12.49   12.46   12.44   12.41   12.38   12.34   12.30   12.25   12.19   12.12   12.04   11.95   11.84   11.71   11.56   11.39  



Column   1 - Simulation time (see above)

Column   2 - Day of the year

Column   3 - Soil temperature for first soil layer division (degrees C)

Column   4 - Soil temperature for second soil layer division (degrees C)

...

Column n+2 - Soil temperature for soil layer division n (degrees C)



WARNING:

This file can become very large.



==============================================================================

SUMMARY.OUT:



      time jday     tmax     tmin      ppt      N2Oflux       NOflux          CH4          NIT      CO2resp

 1971.0000    1     -.15     -.89      .08        .1034       1.7173       9.2292       5.1688    1822.6162



Column 1  - Simulation time (see above)

Column 2  - Day of the year

Column 3  - Maximum temperature for day (degrees C)

Column 4  - Minimum temperature for day (degrees C)

Column 5  - Precipitation for day (cm)

Column 6  - Nitrous oxide flux (gN/ha)

Column 7  - Nitric oxide flux (gN/ha)

Column 8  - Methane oxidation (gCH4/ha)

Column 9  - Gross nitrification (gN/ha)

Column 10 - Heterotrophic CO2 respiration for the day (gCO2/ha)



==============================================================================

SYSCWK.OUT (weekly system carbon):



  time  wk       livec       deadc       soilc        sysc    CO2resp

1971.00   1    150.0000    149.0466   3379.6123   3678.6589     1.3414



Column 1 - Simulation time (see above)

Column 2 - Week of the month, 1 - 5

Column 3 - C live material (gC/m^2)

           (aglivc + bglivc + rleavc + frootc + fbrchc + rlwodc + crootc)

Column 4 - C in dead material (gC/m^2)

           (stdedc + metabc(1) + strucc(1) + wood1c + wood2c + wood3c)

Column 5 - C in soil organic matter pools (gC/m^2)

           (metabc(2) + strucc(2) + som1c(1) + som1c(2) + som2c + som3c)

Column 6 - System C (gC/m^2) (livec + deadc + soilc)

Column 7 - Summation of heterotrophic CO2 respiration for the week (g/m^2)



==============================================================================

TGMONTH.OUT (monthly summation of trace gas fluxes):



  time       N2Oflux        NOflux        N2flux           CH4           NIT         PPT

 1759.00      0.001785      0.006034      0.000015      0.011689      0.088705    21.199900



Column 1 - Simulation time (see above)

Column 2 - Monthly accumulator for nitrous oxide (gN/m^2)

Column 3 - Monthly accumulator for nitric oxide (gN/m^2)

Column 4 - Monthly accumulator for nitrogen gas (gN/m^2)

Column 5 - Monthly accumulator for methane oxidation (gCH4/m^2)

Column 6 - Monthly accumulator for gross nitrification (gN/m^2)

Column 7 - Monthly accumulator for precipitation, includes irrigation (cm)



==============================================================================

VSWC.OUT (daily volumetric soilwater content by layer):



 1895.00    1    0.3493    0.1939    0.1516    0.1352    0.1249    0.1211    0.1211    0.1211    0.1211    0.1214    0.1283  

 1895.00    2    0.2410    0.1914    0.1520    0.1356    0.1260    0.1211    0.1211    0.1211    0.1211    0.1214    0.1283  



Column   1 - Simulation time (see above)

Column   2 - Day of the year

Column   3 - Volumetric soil water content for soil layer 1, as defined in

             soils.in file

Column   4 - Volumetric soil water content for soil layer 2, as defined in

             soils.in file

...

Column n+2 - Volumetric soil water content for soil layer n, as defined in

             soils.in file



NOTE:

n = number of soil layers defined in soils.in file



==============================================================================

WATRBAL.OUT (daily water balance):



0=(swc1-swc2)+ppt+melt-accum-intrcpt-evap-transp-outflow

   time jday     ppt   accum   dsnlq    melt intrcpt    evap  transp  sublim      dswc outflow   balance    snow    snlq  runoff 

1895.00    1   0.000   0.000   0.000   0.000   0.000  -0.460  -0.121   0.000  0.16281   0.000  -0.41821   0.000   0.000   0.000 



Column  1 - Simulation time (see above)

Column  2 - Day of the year

Column  3 - Precipitation for day (cm H2O)

Column  4 - The amount of snow added to the snowpack (cm H2O)

Column  5 - The difference in liquid water in the snowpack from the beginning

            of the day to the end of the day (cm H2O)

Column  6 - The amount of snow melted from the snow pack (cm H2O)

Column  7 - Interception of precipitation by standing crop and litter (cm H2O)

Column  8 - Evaporation (cm H2O)

Column  9 - Transpiration (cm H2O)

Column 10 - Amount of snow sublimated (equivalent to cm H2O)

Column 11 - The difference in the soil water content from the beginning of the

            day to the end of the day (cm H2O)

Column 12 - Water that runs off or drains out of the soil profile (cm H2O)

Column 13 - Daily water balance, computed as:

              balance = (soil water content at beginning of day -

                         soil water content at end of day) + precipitation +

                         snow melt - accumulation - interception -

                         evaporation - transpiration - outflow

            (should be equal to zero)

Column 14 - snow pack for the day (cm H2O)

Column 15 - liquid in snow for the day (cm H2O)

Column 16 - runoff amount for the day (cm H2O)



NOTE:

The model does not attempt to maintain a water balance when simulating a water

table.  (See water table notes below.)



==============================================================================

WFLUX.OUT (daily water flux through the bottom of soil layers):



    time  jday      wflux[0]      wflux[1]      wflux[2]      wflux[3]      wflux[4]      wflux[5]      wflux[6]      wflux[7]      wflux[8]      wflux[9]        etc...

 1895.00     1      0.018261      0.028582      0.020435      0.012795      0.000008      0.000008      0.000008      0.000008      0.000008      0.000007      0.000008      0.000008  



Column   1 - Simulation time (see above)

Column   2 - Day of the year

Column   3 - Water flux from soil layer 1 (index 0) to soil layer 2 (index 1), 

             as defined in soils.in file (cm H2O/day) 

Column   4 - Water flux from soil layer 2 (index 1) to soil layer 3 (index 2),

             as defined in soils.in file (cm H2O/day)

...

Column n+2 - Water flux from soil layer n (index n-1) to deep storage layer

             n+1 (index n) (cm H2O/day)



NOTES:

Negative values represent upward flow (evaporation), positive values represent

downward flow (drainage).



n = number of soil layers defined in soils.in file



==============================================================================

WFPS.OUT (daily water filled pore space by layer):



 1895.00    1   0.7587   0.4211   0.3292   0.2936   0.2714   0.2630   0.2630   0.2630   0.2630   0.2637   0.2787  

 1895.00    2   0.5236   0.4158   0.3302   0.2946   0.2737   0.2630   0.2630   0.2630   0.2630   0.2637   0.2787  



Column   1 - Simulation time (see above)

Column   2 - Day of the year

Column   3 - Water filled pore space for soil layer 1, as defined in soils.in

             file, value from 0 to 1 where 1 = saturation

Column   4 - Water filled pore space for soil layer 2, as defined in soils.in

             file, value from 0 to 1 where 1 = saturation

...

Column n+2 - Water filled pore space for soil layer n, as defined in soils.in

             file, value from 0 to 1 where 1 = saturation



NOTE:

n = number of soil layers defined in soils.in file



==============================================================================

YEAR_SUMMARY.OUT (yearly summation of trace gas fluxes):



  time       N2Oflux        NOflux        N2flux           CH4           NIT      ANNPPT

 1971.92      0.165579      0.609097      0.015456      0.281627      8.175213    58.685108



Column 1 - Simulation time (see above)

Column 2 - Annual accumulator for nitrous oxide (gN/m^2)

Column 3 - Annual accumulator for nitric oxide (gN/m^2)

Column 4 - Annual accumulator for nitrogen gas (gN/m^2)

Column 5 - Annual accumulator for methane oxidation (gCH4/m^2)

Column 6 - Annual accumulator for gross nitrification (gN/m^2)

Column 7 - Annual accumulator for precipitation, includes irrigation (cm)



==============================================================================

==============================================================================

Optional input files for DayCent 4.5.



------------------------------------------------------------------------------

nscale.dat:



The optional multipliers on N inputs contained in this file can be used to

scale the amount of fertilizer added through FERT events, the amount of

atmospheric N deposition, or both.  This file is organized in 13 columns.

Column 1 is the year.  Columns 2 - 13 contain the N input scalars.  A value of

1.0 used for a scalar will have no effect on the amount of N input.  A value

of less that 1.0 used for a scalar will reduce the N input amount.  A value of

greater than 1.0 used for the scalar will increase the N input amount.  A

value of less than 0.0 in the nscale.dat file is invalid and the model will

use the value of 0.0 for the scalar in this case, in effect eliminating the N

inputs.



------------------------------------------------------------------------------

omadscale.dat:



The optional multiplier on OMAD inputs contained in this file can be used to

scale the amount of organic matter added through OMAD events.  This file is

organized in 13 columns.  Column 1 is the year.  Columns 2 - 13 contain the

OMAD scalars.  A value of 1.0 used for a scalar will have no effect on the

amount of organic matter input.  A value of less that 1.0 used for a scalar

will reduce the organic matter input amount.  A value of greater than 1.0 used

for the scalar will increase the organic matter input amount.  A value of less

than 0.0 in the omadscale.dat file is invalid and the model will use a value

of 0.0 for the scalar in this case, in effect eliminating the OMAD inputs.



------------------------------------------------------------------------------

phscale.dat:



The optional multiplier on pH can be used to scale the amount of pH in the

soil, for example to simulate liming experiments.  This file is organized in

13 columns.  Column 1 is the year.  Columns 2 - 13 contain the pH scalars.  A

value of 1.0 used for a scalar will have no effect on the soil pH.  A value of

less that 1.0 used for a scalar will reduce the soil pH.  A value of greater

than 1.0 used for the scalar will increase the soil pH.  All of the scalars

are applied against the pH value as read from the site file.  A value of less

than 0.0 in the phscale.dat file is invalid and the model will use the value

of 1.0 for the scalar in this case, in effect eliminating any shift in pH.



------------------------------------------------------------------------------

tmaxscale,dat, tminscale.dat, and precscale.dat:



We have added options to allow the user to use scalars on the weather file

inputs to simulate climate change scenarios.  The scalars are stored in the

tmaxscale.dat, tminscale.dat, and precscale.dat for modifying maximum

temperature, minimum temperature, and/or precipitation respectively.  The

temperature scalars are addends and the precipitation scalars are multipliers.

These files are organized in 13 columns.  Column 1 is the year.  Columns

2 - 13 contain the scalars. Temperature scalars of 0.0 will have no effect on

the simulated temperature.  Precipitation scalars of 1.0 will have no effect

on the simulated precipitation amount.  These three files are optional and if

the scalars are not used you do not need to have these files in your working

directory.



==============================================================================

==============================================================================

Code changes for DayCent 4.5.



==============================================================================

Temperature curve change:



The temperature effect is now being computed using an arctangent curve,

previous versions of the model used an exponential curve.  The teff(4)

parameter values read from the FIX.100 file are used in the temperature

equation.

     TEFF(1) = "x" location of inflection point

     TEFF(2) = "y" location of inflection point

     TEFF(3) = step size (distance from the maximum point to the minimum

               point)

     TEFF(4) = slope of line at inflection point



The conversion utility assigns the following default values to these

parameters.

     15.4000          'TEFF(1)'

     11.7500          'TEFF(2)'

     29.7000          'TEFF(3)'

     0.03100          'TEFF(4)'



==============================================================================

Options for computing the water effect on decomposition included:



DayCent users have the option of using three different water curves to

calculate the water effect on decompostion depending on the parameter value

entered for the IDEF parameter in the FIX.100 file.



     IDEF = 1, use relative water content

     IDEF = 2, use ratio of precipitation to potential evapotranspiration

     IDEF = 3, use water filled pore space



==============================================================================

Non-symbiotic soil N fixation change:



Non-symbiotic soil N fixation is now being computed using annual 

evapotranspiration in place of precipitation.

     Old equation:

          non-symbiotic N fixation = epnfs(1) + 

                                     epnfs(2)*MIN(annual precipitation,100.0)

     New equation:

          non-symbiotic N fixation = epnfs(2) *

                                    (annual evapotranspiration - epnfs(1))



The conversion utility assigns the following default values for the parameters

used in this equation.

     EPNFS(1) - 30.0000

     EPNFS(2) - 0.01000



==============================================================================

Phosphorus changes:



When running a simulation with phosphorus (NELEM >= 2) a back flow calculation

for flowing phosphorus from occluded P to secondary P has been added.  An

additional input parameter, PSECOC2, was added to the FIX.100 file to

parameterize the calculation for this flow.  The original PSECOC variable in

the FIX.100 file retains its original definition but has been renamed PSECOC1.

The conversion utility changes the PSECOC variable name to PSECOC1, adds the

new PSECOC2 parameter to the FIX.100 file, and sets a default value of 0.0000

for the new PSECOC2 parameter.



We have also implemented a check in the code to adjust the C/N ratio of leaves

when simulating phosphorus so that the N/P ratio of the leaves does not exceed

an observed critical value.  The new MAXNP parameter in the TREE.100 file

represents this critical value.



==============================================================================

Dynamic C allocation:



Grassland/crop system -



In the grassland/crop system the root to shoot carbon allocation is done as a

function of soil water and soil nutrient functions.  The new input parameters

in the CROP.100 file for controlling dynamic carbon allocation are:

     FRTCINDX    - plant growth type

                     0 - use Great Plains equation to compute root to shoot

                         ratio (fixed carbon allocation based on rainfall)

                     1 - perennial plant (i.e., grass, dynamic carbon

                         allocation)

                     2 - annual plant (i.e., crop, dynamic carbon allocation)

                     3 - perennial plant, growing degree day implementation,

                         dynamic carbon allocation

                     4 - non-grain filling annual plant, growing degree day

                         implementation, dynamic carbon allocation

                     5 - grain filling annual plant, growing degree day

                         implementation, dynamic carbon allocation

                     6 - grain filling annual plant that requires a

                         vernalization period (i.e. winter wheat), growing

                         degree day implementation, dynamic carbon allocation

     FRTC(1)     - fraction of C allocated to roots at planting, with no water

                   or nutrient stress, used when FRTCINDX = 2, 4, 5, or 6

     FRTC(2)     - fraction of C allocated to roots at time FRTC(3), with no

                   water or nutrient stress, used when FRTCINDX = 2, 4, 5 or 6

     FRTC(3)     - time after planting (months with soil temperature greater

                   than RTDTMP) at which the FRTC(2) value is reached, used

                   when FRTCINDX = 2, 4, 5, or 6

     FRTC(4)     - maximum increase in the fraction of C going to the roots

                   due to water stress, used when FRTCINDX = 2, 4, 5, or 6

     FRTC(5)     - maximum increase in the fraction of C going to the roots

                   due to nutrient stress, used when FRTCINDX = 2, 4, 5 or 6

     CFRTCN(1)   - maximum fraction of C allocated to roots under maximum

                   nutrient stress, used when FRTCINDX = 1 or 3

     CFRTCN(2)   - minimum fraction of C allocated to roots with no nutrient

                   stress, used when FRTCINDX = 1 or 3

     CFRTCW(1)   - maximum fraction of C allocated to roots under maximum

                   water stress, used when FRTCINDX = 1 or 3

     CFRTCW(2)   - minimum fraction of C allocated to roots with no water

                   stress, used when FRTCINDX = 1 or 3



Tree system -



In the tree system carbon is allocated to fine roots and leaves first.  The

allocation to leaves is based on forest type and growing season.  For

deciduous trees growth occurs only between the months of leaf out and leaf

drop.  For deciduous and drought deciduous forests all of the C is allocated

to leaves during the leaf out period.  In tree growth periods that are not

identified as leaf out periods carbon is allocated to fine roots first then to

leaves, up to a optimum LAI based on large wood biomass.  Any leftover C to be

allocated after partitioning to fine roots and leaves is then distributed to

the woody components, fine branches, coarse roots, and large wood, based on a

normalizing of the carbon allocation fractions defined for the tree in the

TREE.100 file, FCFRAC(3,*), FCFRAC(4,*), and FCFRAC(5,*).  Potential tree

production is now controlled by the PRDX(2) (formerly PRDX(3)), maximum net

forest production, input parameter only, the original PRDX(2) parameter is no

longer being used and has been removed from the file.  The new input

parameters in the TREE.100 file for controlling dynamic carbon allocation are:

     TFRTCN(1)   - maximum fraction of C allocated to fine roots under maximum

                   nutrient stress

     TFRTCN(2)   - minimum fraction of C allocated to fine roots with no

                   nutrient stress

     TFRTCW(1)   - maximum fraction of C allocated to fine roots under maximum

                   water stress

     TFRTCW(2)   - minimum fraction of C allocated to fine roots with no water

                   stress



==============================================================================

Maintenance respiration:



In addition to heterotrophic respiration from decomposition, RESP(1), DayCent

4.5 includes submodels to simulate maintenance respiration.  A user defined

portion of net primary production, NPP, is allocated to the maintenance

respiration pool.  This pool supplies C for maintenance respiration for above

and belowground plant compartments.  Respiration for each plant compartment is

a function of the mass of the compartment, soil or air temperature, and a user

defined maximum respiration parameter. 



The new input parameters for controlling maintenance respiration in the

CROP.100 file are:

     KMRSP(1)    = the fraction of net primary production that goes to the

                   maintenance respiration storage pool for crops

     CKMRSPMX(1) = maximum fraction of aboveground live C that goes to

                   maintenance respiration for crops

     CKMRSPMX(2) = maximum fraction of belowground live C that goes to

                   maintenance respiration for crops



The new input parameters for controlling maintenance respiration in the

TREE.100 file are:

     KMRSP(2)    = the fraction of net primary production that goes to the

                   maintenance respiration storage pool for trees

     FKMRSPMX(1) = maximum fraction of live leaf C that goes to maintenance

                   respiration for trees

     FKMRSPMX(2) = maximum fraction of live fine root C that goes to

                   maintenance respiration for trees

     FKMRSPMX(3) = maximum fraction of live fine branch C that goes to

                   maintenance respiration for trees

     FKMRSPMX(4) = maximum fraction of live large wood C that goes to

                   maintenance respiration for trees

     FKMRSPMX(5) = maximum fraction of live coarse root C that goes to

                   maintenance respiration for trees



NOTE:  The maintenance respiration code has not been fully tested and

validated at this point.  There are some inconsistencies in the carbon balance

when running the model with the maintenance respiration turned on.  Until the

maintenance respiration code has been fully tested and validated we recommend

that you run your simulations with the maintenance respiration turned off.  To

do this set the parameter values for KMRSP(*), CKMRSPMX(*), and FKMRSPMX(*) to

0.0.



==============================================================================

Changes to the savanna submodel:



The SITPOT variable value will be dynamic and will be computed as a function

of average annual precipitation.  Average annual precipitation is calculated

by summing the PRECIP(*) values from the <site>.100 files.  For tuning

purposes the SITPOT parameter value read from the TREE.100 file for the

current tree will be used as a multiplier.

     if (arain .lt. 30.0) then

       sitpot = 1000.0

     else if (arain .gt. 80.0) then

       sitpot = 3500.0

     else

       sitpot = line(arain, 30.0, 1000.0, 80.0, 3500.0)

     endif

     sitpot = sitpot * sitpot_m

Where:

     arain    = average annual rainfall

     sitpot_m = sitpot value for current tree as read from TREE.100 file

And:

     The line function returns the following value:

          line = (y2 - y1) / (x2 - x1) * (x - x2) + y2

          Where:

               x  = arain

               x1 = 30.0 

               y1 = 1000.0

               x2 = 80.0

               y1 = 3500.0

The conversion utility sets all of the SITPOT parameters in a converted

TREE.100 file to 1.0 for no multiplicative effect.



We have also modified the way that the tree basal area is being calculated.

Old code:

        wdbmas = (fbrchc + rlwodc) * 2.0

        trbasl = wdbmas / basfct

New code:

        wdbmas = (fbrchc + rlwodc) * 2.0

        basf = (wdbmas/(0.88 * ((wdbmas * 0.01)**0.635)))

        if (basf .lt. 250.0) then

          basf = basf * basfct

        endif

        trbasl = wdbmas / basf

Where:

     wdbmas = wood biomass

     fbrchc = fine branch carbon

     rlwodc = large wood carbon

     trbasl = tree basal area

     basfct = input parameter from TREE.100 file, the value for this input

              parameter will be given a default value of 1.0 by the conversion

              utility



==============================================================================

Fire code changes for charcoal:



There have been changes to fire code so that removal, by burning, of dead fine

branches and dead large wood will occur as the result of a FIRE event rather

than of a TREM event.  A TREM fire event will burn only live leaves, live fine

branches, and live large wood.  A TREM cutting, windstorm or other non-fire

event will allow the removal of dead fine branches and dead large wood in the

same manner as Century 4.0.  When burning dead fine branches and dead large

through a FIRE event the burned carbon in the dead wood can be returned to the

system as charcoal in the passive SOM pool.  (See the changes in the FIRE.100

input parameters for more information on how the charcoal return is 

parameterized.)



==============================================================================

Grazing change:



The GRET(1) parameter from the GRAZ.100 file is no longer being used.  The

value for GRET(1) now being used in the model equations is calculated based on

soil texture so that the fraction of consumed N that is returned is now a

function of clay content.

     if (clay .lt. 0.0) then

       gret(iel) = 0.7

     else if (clay .gt. 0.30) then

       gret(iel) = 0.85

     else

       gret(iel) = line(clay, 0.0, 0.7, 0.30, 0.85)

     endif



The line function returns the following value:

     line = (y2 - y1) / (x2 - x1) * (x - x2) + y2

     Where:

       x  = clay

       x1 = 0.0

       y1 = 0.7

       x2 = 0.30

       y2 = 0.85



==============================================================================

pH effect on decomposition:



A pH effect multiplier has been added to the decomposition equations.  There

are three equations used to simulate bacterial, fungi, and combination pH

effects on decomposition flows as follows:

     SOM1C(1)  - combination

     SOM1C(2)  - bacterial

     SOM2C     - fungi

     SOM3C     - fungi

     METABC(1) - bacterial

     METABC(2) - bacterial

     STRUCC(1) - combination

     STRUCC(2) - combination

     WOOD1C    - combination

     WOOD2C    - combination

     WOOD3C    - combination



The user also has the ability to simulate a shift in soil pH content if

desired.  This is implemented with a change in the schedule file.  If the

value for PHSYS as read from the schedule file is greater than 0 then the next

line in the schedule file contains the start year for the pH shift to begin.

The optional multiplier on pH can be used to scale the amount of pH in the

soil, for example to simulate liming experiments.  The phscale.dat file

contains the pH scalars.  The file is organized in 13 columns.  Column 1 is

the year.  Columns 2 - 13 contain the pH scalars.  A value of 1.0 used for a

scalar will have no effect on the amount of pH.  A value of less that 1.0 used

for a scalar will reduce the pH.  A value of greater than 1.0 used for the

scalar will increase the pH.  All of the scalars are applied against the pH

value as read from the site file.  A value of less than 0.0 in the phscale.dat

file is invalid and the model will use the value of 1.0 for the scalar in this

case, in effect eliminating any shift in pH.  If the pH shift is not being

modeled a value of 0 should be read in for the PHSYS variable.



==============================================================================

Potential production calculation change:



Potential production is now taking into account the photo period effect on

growth.  In the fall, when the day length is decreasing, growth will slow

down.  The definitions for PRDX(1), CROP.100, and PRDX(2), TREE.100, have been

changed.  These parameters now represent the coefficient used when calculating

the potential production as a function of solar radiation outside of the

atmosphere.



Potential grass/crop production is now being computed in the same manner as

potential forest production using an estimate for total production rather than

estimating potential aboveground production only.  The allocation of

aboveground to belowground production for the grass/crop is now based on the

fraction of root carbon rather than the root to shoot ratio.



We recommend using a value of 0.5 for PRDX(1) and PRDX(2).



==============================================================================

Automatic fertilization:



Automatic fertilization was not working correctly in earlier versions of

Century.  Alister Metherell's modifications for the implementing the automatic

fertilization option were added to DayCent 4.5.



==============================================================================

Irrigation change:



Irrigation will be allowed to occur even on days when the temperature is

below freezing.  This change was made to allow an irrigated system to reach

anerobic conditions even if the temperature is low.



==============================================================================

Implementation of a water table:



DayCent can be parameterized to simulate a water table.  When simulating a

water table soil water in the deep storage will not drain out of the profile.

This soil water will be permitted have an upward flow (evaporation) in the

soil profile.  To parameterize for a water table set the watertable variable

in the sitepar.in file to 1 for months in which a water table should be

maintained by the model.  It will also be necessary to set parameter

values for hpotdeep, hydraulic water potential of deep storage layer (for

maximum upward flow potential set this variable to 0.0), and ksatdeep,

saturated hydraulic conductivity of deep storage layer, in the sitepar.in

file.  DayCent will not attempt to maintain a water balance when simulating a

water table.



==============================================================================

Changes in snow routines:



Previous versions of DayCent used hard coded parameter values for the snow

melt equation.  This has been changed so that the TMELT(*) parameters from the

fix.100 file are now being used in the snow melt equation.



The snow submodel has been modified so that order of events for snow has been

changed from accumulate, melt, sublimate to accumulate, sublimate, melt.



We have also added a solar radiation effect to the snow melt equation.  This

will require you to modify the value of TMELT(2) in your FIX.100 file from the

value used by earlier versions of the model.  We recommend using a default

value of 0.002 for this parameter.



==============================================================================

Runoff:



Since runoff calculations have been added to the model the storm flow is no

longer being calculated.  Runoff occurs when the water available for input

into the soil, from precipitation and/or snow melt, can not be infilitrated

into the soil due to impedence (from frozen soil layers) or the volume of

water is large enought that it cannot drain into the soil in the amount of

time alloted (hours_rain parameter in the sitepar.in file).  Due to this

change the STORMF variable in the <site>.100 file in no longer being used and

should be set to a value of 0.0.  The STREAM(1) output variable represents

baseflow + runoff.



==============================================================================

Dynamic value for NLAYPG:



The amount of soil water and mineral N, P, and S that is available for plant

growth is now based on a dynamic NLAYPG value.  Each crop and tree option will

have a specific NLAYPG value assigned to them in the CROP.100 (CLAYPG) and

TREE.100 (TLAYPG) files.  Any time a crop and/or tree option is changed the

value for NLAYPG will be recomputed.  In a grassland system the value for

NLAYPG will be based on the CLAYPG value read for the current crop option from

the CROP.100 file.  In a forest system the value for NLAYPG will be based on

the TLAYPG value read for the current tree option from the TREE.100 file.  In

a savanna system the value for NLAYPG will be weighted based on the crop/grass

LAI, tree LAI, and the CLAYPG and TLAYPG values.



The new NLAYPG value is also used for computing soil transpiration.  Soil

transpiration will occur from the top NLAPYG layers in the soil profile rather

than from the full soil profile.



The NLAYPG value from the <site>.100 file is no longer being used.



==============================================================================

User specified temperatures for leaf out and leaf drop in deciduous trees:



There have been two additional variables added to the TREE.100 file to allow

the user to specify the temperature values for controlling leaf out, TMPLFS,

and leaf drop, TMPLFF, for the specified tree.  These temperature values are

in degrees C.



==============================================================================

Change in PET calculation:



The PET calculation is now taking into account solar radition outside of the

atmosphere and an approximated cloud cover based on temperature range.  As a

result of this change the FWLOSS(4) parameter in the FIX.100 file needs to be

rescaled.  A default value of 0.8 is now recommended for this parameter.



==============================================================================

Fractional volume of rock used to modify field capacity and wilting point:



The ROCK parameter has been added to the <site>.100 file and will be used for

modifying the AFIEL(*) and AWILT(*) values when SWFLAG is not equal to 0.  Set

this parameter value to 0.0 to run a simulation with no rock effect on field

capacity and wilting point values.



==============================================================================

Weekly scheduling:



The scheduling of events is now being done using year and day of the year

rather than year and month.  This means that events can be scheduled to occur

in the simulation within the specific simulation week that the contains day of

the year for the event.



Fertilization addition is an exception to this rule, fertilizer will be

applied on the day which the event is scheduled in the schedule file.



The calendar used for scheduling the events is for a non-leap year.



In the new weekly scheduling scheme the following events will have effects

that will continue over a 1 month period:

     CULT - the multipliers for increased decomposition will be used for one

            month

     EROD - enter the per week amount of erosion, this erosion loss will

            continue over a one month period

     GRAZ - grazing events will continue for a month and restrictions on

            production due to grazing will be effect for one month

     IRRI - the amount of specified irrigation will be applied weekly over a 1

            month period, the amount of irrigation that will be applied during

            a given week will depend on the fraction of the month that the

            simulation week represents

     SENM - no growth will occur in the one month period that follows the

            scheduled senescence event

If more than one of these events is scheduled within a one month period the

original unexpired event will be replaced by the new event and the new event's

effects will linger as described above.



NOTE:  When DayCent reads the scheduling information from the schedule file it

       is assuming non-leap years.  This can cause a problem when events are

       scheduled for the first day of the month for months following February.

       For example, events scheduled for days 182, 213, and 244, the first day

       of July (month 7), August (month 8) and September (month 9)

       respectively in a non-leap year, will occur in the last week of June

       (month 6), July (month 7), and August (month 8) respectively in a leap

       year.  However, since we are assuming non-leap years when creating the

       schedule of events, day 182 is scheduled as occurring in July (month

       7), day 213 is scheduled as occurring in August (month 8), and day 244

       is scheduled as occurring in September (month 9) by the model when

       reading the schedule file.  This causes a problem in the leap year

       because the event scheduled for day 182 is scheduled for month 7 but in

       the leap year day 182 occurs in month 6.  Since we never meet the

       condition of day 182 occurring in month 6 in the leap year the event

       scheduled for this day does not occur in the leap year.  To prevent

       this type of problem from occurring schedule your events for the second

       day of the month for months following February, 183, 214, or 245 in the

       example above.  This day will occur in the first week of the month in

       both a leap year and a non-leap year.



       Although events can be scheduled weekly, when creating a schedule file

       for use by the DayCent model please keep in mind that the schedule file

       is still being read monthly.  This means that if you create a

       scheduling with more than one option for a specific event type (CULT,

       HARV, etc.) within a given month only one event of each type will be

       used per month.  In a case where you have two, or more, events of the

       same type scheduled to occur within the same month as the schedule file

       is read any subsequent events for the month will overwrite any

       preceding event of the same type for the month and only the last event

       of that type will occur in the simulation.



==============================================================================

Soil warming experiments can now be simulated:



The soil surface temperature warming option allows the user to simulate

experiments where the soil surface temperature is warmed without an increase

in the minimum and maximum air temperature values.  The soil surface warming

option is implemented in the same manner the CO2 effect and the pH shift

effect options.  If the value for stsys as read from the schedule file header

is greater than 0 then the next line in the schedule file header contains the

start year for the soil surface warming and the following line contains the

amount to warm the soil surface temperature in degrees C.



==============================================================================

Implementation of a growing degree day submodel:



If desired, plant growth can be set to occur using a growing degree day

submodel.  When using the growing degree day submodel the start and end of

plant growth will be triggered based on phenology (soil surface temperature,

air temperature, and thermal units) rather than hard wired to occur at a

specific time by the schedule file.



The following parameters in the crop.100 file control the growing degree day

submodel implementation:

     FRTCINDX    - plant growth type

                        0 - use Great Plains equation to compute root to shoot

                            ratio (fixed carbon allocation based on rainfall)

                        1 - perennial plant (i.e., grass, dynamic carbon

                            allocation)

                        2 - annual plant (i.e., crop, dynamic carbon

                            allocation)

                        3 - perennial plant, growing degree day

                            implementation, dynamic carbon allocation

                        4 - non-grain filling annual plant, growing degree day

                            implementation, dynamic carbon allocation

                        5 - grain filling annual plant, growing degree day

                            implementation, dynamic carbon allocation

                        6 - grain filling annual plant that requires a

                            vernalization period (i.e. winter wheat), growing

                            degree day implementation, dynamic carbon

                            allocation

     TMPGERM     - germination temperature for the growing degree day

                   submodel, will cause a FRST event when FRTCINDX = 3 or a

                   PLTM event when FRTCINDX = 4, 5, or 6 (degrees C)

     DDBASE      - number of degree days required to trigger a senescence

                   (SENM) event for a perennial (FRTCINDX = 3), maturity and

                   harvest (HARV) for a non-grain filling annual

                   (FRTCINDX = 4), or to reach anthesis (flowering) for a

                   grain filling annual (FRTCINDX = 5 or 6)

     TMPKILL     - temperature at which growth will stop when using the

                   growing degree day submodel, will cause a SENM and LAST

                   event when FRTCINDX = 3 or a HARV and LAST event if

                   FRTCINDX = 4, 5, or 6, if the required number of thermal

                   units have not been accumulated prior to trigger a SENM or

                   a HARV event (degrees C)

     BASETEMP(1) - base temperature for crop growth, growing degree days will

                   accumulate only on days when the average temperature is

                   greater than the base temperature for the crop (degrees C)

     BASETEMP(2) - ceiling on the maximum temperature used to accumulate

                   growing degree days (degrees C)

     MNDDHRV     - minimum number of degree days from anthesis (flowering) to

                   harvest for grain filling annuals (FRTCINDX = 5 or 6)

     MXDDHRV     - maximum number of degree days from anthesis (flowering) to

                   harvest for grain filling annuals (FRTCINDX = 5 or 6)



If FRTCINDX is set to 0, 1, or 2 plant growth will be controlled by the FRST,

HARV, LAST, and SENM events as defined in the schedule file.



When simulating plant growth using the growing degree day submodel it will

still be necessary to include FRST/PLTM, SENM/HARV events in your schedule

file, however, the timing of these events will occur based on phenology.



If FRTCINDX is set to 3 (perennial grass - growing degree day submodel) a FRST

will occur if the surface temperature is greater than or equal to TMPGERM for

the current crop option and a FRST event was scheduled prior to the end of

the current simulation week.  A SENM event will occur in one of two cases:

  1) if the number of thermal units that have accumulated since the FRST event

     are greater than or equal to DDBASE for the current crop option and a

     SENM event was scheduled prior to the end of the current simulation week

or

  2) if the minimum temperature for any day in the current simulation time

     step is less than or equal to TMPKILL for the current crop option and a

     SENM event was scheduled prior to the end of the current simulation week.

If a FRST does not occur in a given simulation year then a SENM will not occur

in that simulation year.



If FRTCINDX is set to 4, 5, or 6 (annual crop - growing degree day submodel) a

PLTM will occur if the surface temperature is greater than or equal to TMPGERM

for the current crop option and a PLTM event was scheduled prior to the end of

the current simulation week.  A HARV event will occur in one of two cases:

  1) for crop type 4 if the number of thermal units that have accumulated

     since the PLTM event are greater than or equal to DDBASE for the current

     crop option and a HARV event was scheduled prior to the end of the

     current simulation week, for crop types 5 or 6 if the number of thermal

     units that have accumulated since the PLTM event are greater than or

     equal DDBASE+MXDDHRV for the current crop option and a HARV event was

     scheduled to occur prior to the end of the current simulation week or if

     the crop has reached anthesis (DDBASE) and drought stress occurs and a

     HARV event was scheduled to occur prior to the end of the current

     simulation week

or

  2) if the minimum temperature for any day in the current simulation time

     step is less than or equal to TMPKILL for the current crop option and a

     HARV event was scheduled prior to the end of the current simulation week.

If a PLTM does not occur in a given simulation year then a HARV will not occur

in that simulation year.



The triggering of a SENM/HARV event due to a killing frost (minimum

temperature <= TMPKILL) will not occur until at least 1/2 of the thermal units

for the current crop have been accumulated based on the DDBASE parameter

value for the current crop.



When simulating an annual crop that requires a vernalization period

(FRTCINCX = 6) the degree day accumulator will not start accumulating until

the simulation has passed through the vernalization period.  This will occur

when the number of hours in the day is increasing (end of December in the

northern hemisphere or end of June in the southern hemisphere).



Note:  When using the growing degree day submodel a SENM or HARV event will

automatically trigger a LAST event, therefore a LAST event should not be

included when creating a schedule file for a plant that will be grown using

the growing degree implementation.



------------------------------------------------------------------------------

When FRTCINDX is set to 3 or 4 change the growing degree day implementation so

that crop growth is stopped by a harvest event rather than the growing degree

day accumulator.  Also, add a check to force a harvest if the day length is

less than 12 hours long and is decreasing for FRTCINDX 3-6.



Set an upper limit on the calculation for accumulating growing degree days

such that when the maximum temperature for the day is capped.  This requires

adding a second BASETEMP parameter to each crop option in the CROP.100 file.



May 2008



==============================================================================

Added ability to simulate reduction factor on nitrification when fertilizing:



A new parameter, NINHIB, added to the FERT.100 file represents a reduction

factor on nitrification rates due to nitrification inhibitors added to the

site with the fertilizer.  This parameter value is used as a multiplier in the

calculation of the nitrification rate.  A value of 1.0 for this parameter will

have no effect on the nitrification rate.  The reduction in nitrification rate

will linger for one month after the fertilizer application.



Additionally the NINHTM paramter added to the FERT.100 file determines how

long, in number of simulation weeks, to simulate the effect of the nitrogen

inhibitor from the fertilizer addition.



==============================================================================

Added ability to simulate a lag in drainage of soil profile after a rain

event for sites with poorly drained soils:



A drainlag parameter was added to the sitepar.in file (see below) to allow the

user to set number of days between a rainfall, snowmelt, or irrigation event

and the drainage of soil profile.  Use a value of 0 for this parameter to

allow drainage of the soil profile to occur on the day that the rainfall,

snowmelt, or irrigation event occurs as in earlier versions of the DayCent

model.  When entering a value of -1 for this parameter the number of days

between the rainfall, snowmelt, or irrigation event will be computed based

on the soil texture in the soils.in file.  The maximum number of days between

water addition and drainage of the soil is constrained to <= 5 to prevent

numerical instabilities in the water flux subroutine.



==============================================================================

Added ability to turn off the respiration restraint on denitrification:



The start day of the year and end day of the year added to the sitepar.in file

(see below) allow the user to turn off the respiration restraint on

denitrification during the days off the year the fall between the given days.



==============================================================================

The VOLPL and VOLPLA output variables now include the N that is volatilized

from excreted animal waste:



In the grazing subroutine we are now calculating the amount of N that is

volatilized from excreted faeces and urine.  This volatilized N is added to

the VOLPL and VOLPLA output variables.



==============================================================================

Separate decomposition rates used for surface and soil pools:



When using the relative water content option, IDEF = 1 in the FIX.100 file,

the model will compute separate values for surface and soil decomposition

rates.



The water content in the top soil layer will be used for computing

decomposition for the surface pools; METABC(1), STRUCC(1), SOM1C(1), WOOD1C,

and WOOD2C.



A weighted average of the water content in the 2nd, 3rd, and 4th soil layers

will used for computing decomposition for the soil pools; METABC(2),

STRUCC(2), SOM1C(2), SOM2C, SOM3C, and WOOD3C.  In addition this soil

decomposition rate will be used in the growth and phosphorous weathering

calculations.



==============================================================================

Added an option to allow the use of scalars on the N inputs:



The optional multiplier on N inputs can be used to scale the amount of

fertilizer added through FERT events, the amount of atmospheric N deposition,

or both.  The optional N scalar option is implemented in the same manner as

the CO2 effect, the pH shift effect, and the soil surface warming options.

If the value for Nstart as read from the schedule file header is greater than

0 then the next line in the schedule file header contains the start year for

the use of the N input scalars.  Valid N input scalar options are as follows:

     0 - No scalars used

     1 - Use scalars on FERT options only

     2 - Use scalars on atmospheric N deposition only

     3 - Use scalars on both FERT options and atmospheric N deposition



The nscale.dat file contains the N input scalars.  The file is organized in 13

columns.  Column 1 is the year.  Columns 2 - 13 contain the N input scalars.

A value of 1.0 used for a scalar will have no effect on the amount of N input.

A value of less that 1.0 used for a scalar will reduce the N input amount.  A

value of greater than 1.0 used for the scalar will increase the N input

amount.  A value of less than 0.0 in the nscale.dat file is invalid and the

model will use the value of 0.0 for the scalar in this case, in effect

eliminating the N inputs.



==============================================================================

Added an option to allow the use of scalars on the OMAD inputs:



The optional multiplier on OMAD inputs can be used to scale the amount of

organic matter added through OMAD events.  The optional OMAD scalar option is

implemented in the same manner as the CO2 effect, the pH shift effect, and the

soil surface warming options.  If the value for OMADstart as read from the

schedule file header is greater than 0 then the next line in the schedule file

header contains the start year for the use of the OMAD scalars.  Valid OMAD

input scalar options are as follows:

     0 - No scalars used

     1 - Use scalars on OMAD options



The omadscale.dat file contains the OMAD scalars.  The file is organized in 13

columns.  Column 1 is the year.  Columns 2 - 13 contain the OMAD scalars.  A

value of 1.0 used for a scalar will have no effect on the amount of organic

matter input.  A value of less that 1.0 used for a scalar will reduce the

organic matter input amount.  A value of greater than 1.0 used for the scalar

will increase the organic matter input amount.  A value of less than 0.0 in

the omadscale.dat file is invalid and the model will use a value of 0.0 for

the scalar in this case, in effect eliminating the OMAD inputs.



==============================================================================

Changes made to decomposition subroutine:



When running simulations for the dry CPR site it was discovered that the soil

and surface litter decay was occurring too fast.  To address this problem

we changed the decomposition calculations to use relative water content as

relative water content is texture independent and the same curve can work for

multiple soil types.



==============================================================================

Fix for evaporation calculations:



When calculating evaporation if the top soil layer was too dry to allow

evaporation the water for the evaporation was being pulled from the bottom-

most layers in the soil profile.  Changes were made so that evaporation will

come from the second soil layer only when the top soil layer gets too dry.



==============================================================================

Add pulse multipliers to the computation for water effect on decomposition:



These multipliers work in the same manner as the pulse multipliers that are

used to increase of NO due to moisture and rain.  For the decomposition

calculations the pulse multiplier is used to enhance soil decomposition

following drying and re-wetting of the soil.



==============================================================================

Fraction of fertilzer that is NH4 and NO3 added to FERT.100 file:



Each fertilizer option in the FERT.100 file now has the fraction of NH4 and

NO3 in the fertilzer defined.  Two new parameters, FRAC_NH4 and FRAC_NH3,

represent the fraction of NH4 (ammonium) and fraction of NH3 (nitrate) in the

fertilzer respectively.  The fraction of N fertilizer that is ammonimum and

the fraction of N fertilizer that is nitrate values should sum to 1.0.



==============================================================================

We are no longer using the shallow, intermediate, deep, and very deep soil

depths to calculate a weighted average value to be used when calculating

transpiration.  The model is now using the wettest layer within the plant

rooting zone to calculate transpiration.  As a result the sitepar.in file

has been modified to remove the input that defines these layers.



==============================================================================

==============================================================================

New output variables in the *.bin output file:



AAGDEFAC      - average annual value of AGDEFAC, the decomposition factor

                which combines the effects of temperature and moisture for the

                surface decomposition (replaces ADEFAC)



ABGDEFAC      - average annual value of BGDEFAC, the decomposition factor

                which combines the effects of temperature and moisture for the

                soil decomposition (replaces ADEFAC)



ACCRSTE(1)    - annual accumulator for N from harvested straw



ACCRSTE(2)    - annual accumulator for P from harvested straw



ACCRSTE(3)    - annual accumulator for S from harvested straw



AGCMTH(12)    - aboveground C production for the grass/crop for the current

                month, 1-12 (gC/m2)



AGCPRD        - aboveground C production for the grass/crop over the last

                completed growing season (gC/m2/y)



AGDEFAC       - decomposition factor based on temperature and moisture for

                surface decomposition (replaces DEFAC)



ANNET         - annual evapotranspiration (cm)



BGCMTH(12)    - belowground C production for the grass/crop for the current

                month, 1-12 (gC/m2)



BGCPRD        - belowground C production for the grass/crop over the last

                completed growing season (gC/m2/y)



BGDEFAC       - decomposition factor based on temperature and moisture for

                soil decomposition (replaces DEFAC)



CMRSPFLUX(1)  - monthly maintenance respiration flux from aboveground

                grass/crop material that flows from the grass/crop maintenance

                respiration storage pool (MRSPSTG(1,*)) to the C source/sink

                pool (CSRSNK) (gC/m2)



CMRSPFLUX(2)  - monthly maintenance respiration flux from belowground

                grass/crop material that flows from the grass/crop maintenance

                respiration storage pool (MRSPSTG(1,*)) to the C source/sink

                pool (CSRSNK) (gC/m2)



CRTPRD        - coarse root component C production for the forest system over

                the last completed growing season (gC/m2/y)



EUPPRD(3)     - E uptake by grass, crop, or tree over the last completed

                growing season (g/m2/y)

                     (1) = N     (2) = P     (3) = S



FBRPRD        - fine branch component C production for the forest system over

                the last completed growing season (gC/m2/y)



FCMTH(12)     - forest system C production for the grass/crop for the current

                month, 1-12 (gC/m2)



FCPRD         - forest system C production over the last completed growing

                season (gC/m2/y)



FERTAC(1)     - annual accumulator for N fertilizer (gN/m2)



FERTAC(2)     - annual accumulator for P fertilizer (gP/m2)



FERTAC(3)     - annual accumulator for S fertilizer (gS/m2)



FERTPRD(1)    - growing season accumulator for N fertilizer (gN/m2)



FERTPRD(2)    - growing season accumulator for P fertilizer (gP/m2)



FERTPRD(3)    - growing season accumulator for S fertilizer (gS/m2)



FERTMTH(12,1) - N fertilizer added to the system for the month, 1-12 (gN/m2)



FERTMTH(12,2) - P fertilizer added to the system for the month, 1-12 (gP/m2)



FERTMTH(12,3) - S fertilizer added to the system for the month, 1-12 (gS/m2)



FMRSPFLUX(1)  - monthly maintenance respiration flux from live leaf material

                that flows from the tree maintenance respiration storage pool

                (MRSPSTG(2,*)) to the C source/sink pool (CSRSNK) (gC/m2)



FMRSPFLUX(2)  - monthly maintenance respiration flux from live fine root

                material that flows from the tree maintenance respiration

                storage pool (MRSPSTG(2,*)) to the C source/sink pool (CSRSNK)

                (gC/m2)



FMRSPFLUX(3)  - monthly maintenance respiration flux from live fine branch

                material that flows from the tree maintenance respiration

                storage pool (MRSPSTG(2,*)) to the C source/sink pool (CSRSNK)

                (gC/m2)



FMRSPFLUX(4)  - monthly maintenance respiration flux from live large wood

                material that flows from the tree maintenance respiration

                storage pool (MRSPSTG(2,*)) to the C source/sink pool (CSRSNK)

                (gC/m2)



FMRSPFLUX(5)  - monthly maintenance respiration flux from live coarse root

                material that flows from the tree maintenance respiration

                storage pool (MRSPSTG(2,*)) to the C source/sink pool (CSRSNK)

                (gC/m2)



FRTPRD        - fine root component C production for the forest system over

                the last completed growing season (gC/m2/y)



MRSPANN(1)    - total annual maintenance respiration for grass/crop system

                (gC/m2/year)



MRSPANN(2)    - total annual maintenance respiration for forest system

                (gC/m2/year)



MRSPFLOW(1)   - maintenance respiration flow to storage pool from grass/crop

                system (gC/m2)



MRSPFLOW(2)   - maintenance respiration flow to storage pool from forest

                system (gC/m2)



MRSPSTG(1,1)  - unlabeled C in maintenance respiration storage for grass/crop

                system (gC/m2)



MRSPSTG(1,2)  - labeled C in maintenance respiration storage for grass/crop

                system (gC/m2)



MRSPSTG(2,1)  - unlabeled C in maintenance respiration storage for forest

                system (gC/m2)



MRSPSTG(2,2)  - labeled C in maintenance respiration storage for forest system

                (gC/m2)



N2OACC        - annual accumulator for N2O flux (gN/m^2)



N2OPRD        - growing season accumulator for N2O flux (gN/m^2)



N2OMTH(12)    - monthly accumulator of N2O flux (gN/m^2)



OMADAC        - annual accumulator of C added to system through organic matter

                addition events (gC/m2)



OMADAE(1)     - annual accumulator of N added to system through organic matter

                addition events (gN/m2)



OMADAE(1)     - annual accumulator of P added to system through organic matter

                addition events (gP/m2)



OMADAE(1)     - annual accumulator of S added to system through organic matter

                addition events (gS/m2)



OMADMTH(12)   - C added to the system through organic matter addition events

                for the month, 1-12 (gC/m2)



OMADMTE(12,1) - N added to the system through organic matter addition events

                for the month, 1-12 (gN/m2)



OMADMTE(12,2) - P added to the system through organic matter addition events

                for the month, 1-12 (gP/m2)



OMADMTE(12,3) - S added to the system through organic matter addition events

                for the month, 1-12 (gS/m2)



OMADPRD       - growing season accumulator of C added to system through

                organic matter addition events (gC/m2)



OMADPRE(1)    - growing season accumulator of N added to system through

                organic matter addition events (gN/m2)



OMADPRE(2)    - growing season accumulator of P added to system through

                organic matter addition events (gP/m2)



OMADPRE(3)    - growing season accumulator of S added to system through

                organic matter addition events (gS/m2)



RLVPRD        - leaf component C production for the forest system over the

                last completed growing season (gC/m2/y)



RLWPRD        - large wood component C production for the forest system over

                the last completed growing season (gC/m2/y)



RUNOFF        - monthly runoff (cm H2O/month)



STRMAC(1)     - annual accumulator for cm H2O of stream flow (base flow +

                storm flow)



STRMAC(2)     - annual accumulator for N from mineral leaching of stream flow

                (base flow + storm flow) (g/m2)



STRMAC(3)     - annual accumulator for P from mineral leaching of stream flow

                (base flow + storm flow) (g/m2)



STRMAC(4)     - annual accumulator for S from mineral leaching of stream flow

                (base flow + storm flow) (g/m2)



STRMAC(5)     - annual accumulator for C from organic leaching of stream flow

                (base flow + storm flow) (g/m2)



STRMAC(6)     - annual accumulator for N from organic leaching of stream flow

                (base flow + storm flow) (g/m2)



STRMAC(7)     - annual accumulator for P from organic leaching of stream flow

                (base flow + storm flow) (g/m2)



STRMAC(8)     - annual accumulator for S from organic leaching of stream flow

                (base flow + storm flow) (g/m2)



TGZRTE(1)     - total N returned in faeces and urine from a grazing event

                (g/m2)



TGZRTE(2)     - total P returned in faeces and urine from a grazing event

                (g/m2)



TGZRTE(3)     - total S returned in faeces and urine from a grazing event

                (g/m2)



TOTSYSC       - total system C (AGLIVC + BGLIVC + STDEDC + STRUCC(1) +

                STRUCC(2) + METABC(1) + METABC(2) + RLEAVC + FROOTC +

                FBRCHC + RLWODC + CROOTC + WOOD1C + WOOD2C + WOOD3C +

                SOM1C(1) + SOM1C(2) + SOM2C + SOM3C) (g/m2)



TOTSYSE(1)    - total N in system (AGLIVE(1) + BGLIVE(1) + STDEDE(1) +

                STRUCE(1,1) + STRUCE(2,1) + METABE(1,1) + METABE(2,1) +

                RLEAVE(1) + FROOTE(1) + FBRCHE(1) + RLWODE(1) + CROOTE(1) +

                WOOD1E(1) + WOOD2E(1) + WOOD3E(1) + SOM1E(1,1) + SOM1E(2,1) +

                SOM2E(1) + SOM3E(1) (g/m2)



TOTSYSE(2)    - total P in system (AGLIVE(2) + BGLIVE(2) + STDEDE(2) +

                STRUCE(1,2) + STRUCE(2,2) + METABE(1,2) + METABE(2,2) +

                RLEAVE(2) + FROOTE(2) + FBRCHE(2) + RLWODE(2) + CROOTE(2) +

                WOOD1E(2) + WOOD2E(2) + WOOD3E(2) + SOM1E(1,2) + SOM1E(2,2) +

                SOM2E(2) + SOM3E(2) (g/m2)



TOTSYSE(3)    - total S in system (AGLIVE(3) + BGLIVE(3) + STDEDE(3) +

                STRUCE(1,3) + STRUCE(2,3) + METABE(1,3) + METABE(2,3) +

                RLEAVE(3) + FROOTE(3) + FBRCHE(3) + RLWODE(3) + CROOTE(3) +

                WOOD1E(3) + WOOD2E(3) + WOOD3E(3) + SOM1E(1,3) + SOM1E(2,3) +

                SOM2E(3) + SOM3E(3) (g/m2)



VOLEAC        - annual accumulator for N volatilization as a function of N

                remaining after uptake by grass, crop, or tree (g/m2)



VOLGAC        - annual accumulator for N volatilized as a function of gross

                mineralization (g/m2)



VOLPAC        - annual accumulator for N volatilized from plant at harvest,

                senescence, and/or from grazing removal for grass/crop (g/m2)



WD1C2(2)      - dead fine branch respiration (g/m2/mo)

                     (1) = unlabeled     (2) = labeled



WD2C2(2)      - dead large wood respiration (g/m2/mo)

                     (1) = unlabeled     (2) = labeled



WD3C2(2)      - dead coarse roots respiration (g/m2/mo)

                     (1) = unlabeled     (2) = labeled



NOTE:  The growing season accumulator values for carbon production (ACRCIS(*),

AFBCIS(*), AFRCIS(*), AGCACC, AGCISA(*), ALVCIS(*), ALWCIS(*), BGCACC,

BGCISA(*), CRTACC, FBRACC, FCACC, FRTACC, PTAGC, PTBGC, RLVACC, RLWACC) and

the growing season accumulator values for E uptake (EUPACC(*), EUPAGA(*),

EUPBGA(*), and EUPPRT(*,*)) output for the simulation were being reset to 0.0

at the start of the growing season, when a FRST, PLTM, or TFST event occurred.

These production output variables would seem to indicate that production was

still occurring because the output variables were not set back to zero at the

end of a growing season and would retain a constant value until the next FRST,

PLTM or TFST event occurred.  These accumulators are now being reset to 0.0 at

the end of the simulation timestep in which a LAST or TLST event occurs, after

the output for the timestep has been saved to the output file.

Old way:

     Accumulators initialized to 0.0 at start of run

     Accumulators reset to 0.0 on FRST, PLTM, or TFST and begin accumulation

New way:

     Accumulators initialized to 0.0 at start of run

     Accumulators begin accumulation on FRST, PLTM, or TFST

     Accumulators reset to 0.0 on LAST or TLST after output written to file



The new growing season production variables, AGCPRD, BGCPRD, CRTPRD,

EUPPRD(*), FBRPRD, FCPRD, FRTPRD, RLVPRD, and RLWPRD, are set equal to the

value of their associated accumulator value when a LAST or TLST occurs.  These

values can be used when examining yearly output to see the amount of

production that occurred over the previously completed growing season.  These

growing season production variables will be set back to zero in January if no

production has occurred over the previous 12 month period.



The new growing season accumulators for fertilizer addition (FERTAC, FERTMTH,

and FERTPRD), organic matter addition (OMADAC, OMACAE, OMADMTE, OMADMTH,

OMADPRD, and OMADPRD), and N2O flux (N2OACC, N2OMTH, and N2OPRD) are currently

being tracked for the grass/crop system only and will be reset on a LAST

event.



==============================================================================

Created new ASCII weekly output files for live carbon (livec.out), dead carbon

(deadc.out), soil carbon (soilc.out), and system carbon (sysc.out)  (See

additional details above.)



------------------------------------------------------------------------------

Created new ASCII output file for monthly trace gas fluxes, tgmonth.out.  (See

additional details above.)



------------------------------------------------------------------------------

Created new ASCII output files with denitrification N2O and NO flux by layer.

dN2lyr.out and dN2Olyr.out.  (See additional details above.)



==============================================================================

==============================================================================

Parameter file changes:



Century version 4.0 CROP.100, FERT.100, FIRE.100, FIX.100, TREE.100, and

<site>.100 parameter files must be modified to work DayCent 4.5.  Century

version 4.0 schedule files must also be modified to work with DayCent 4.5.  A

conversion utility, daycent_convert100.exe, has been provided to automate

these file modifications using default values for the modified parameters.



------------------------------------------------------------------------------

CROP.100:



The CROP.100 file used by DayCent version 4.5 has 19 additional parameters:

     FRTCINDX    - plant growth type

                     0 - use Great Plains equation to compute root to shoot

                         ratio (fixed carbon allocation based on rainfall)

                     1 - perennial plant (i.e., grass, dynamic carbon

                         allocation)

                     2 - annual plant (i.e., crop, dynamic carbon allocation)

                     3 - perennial plant, growing degree day implementation,

                         dynamic carbon allocation

                     4 - non-grain filling annual plant, growing degree day

                         implementation, dynamic carbon allocation

                     5 - grain filling annual plant, growing degree day

                         implementation, dynamic carbon allocation

                     6 - grain filling annual plant that requires a

                         vernalization period (i.e. winter wheat), growing

                         degree day implementation, dynamic carbon allocation

     FRTC(4)     - maximum increase in the fraction of C going to the roots

                   due to water stress, used when FRTCINDX = 2, 4, 5, or 6

     FRTC(5)     - maximum increase in the fraction of C going to the roots

                   due to nutrient stress, used when FRTCINDX = 2, 4, 5, or 6

     CFRTCN(1)   - maximum fraction of C allocated to roots under maximum

                   nutrient stress, used when FRTCINDX = 1 or 3

     CFRTCN(2)   - minimum fraction of C allocated to roots with no nutrient

                   stress, used when FRTCINDX = 1 or 3

     CFRTCW(1)   - maximum fraction of C allocated to roots under maximum

                   water stress, used when FRTCINDX = 1 or 3

     CFRTCW(2)   - minimum fraction of C allocated to roots with no water

                   stress, used when FRTCINDX = 1 or 3

     KMRSP(1)    - the fraction of net primary production that goes to the

                   carbohydrate storage pool for crops

     CKMRSPMX(1) - maximum fraction of aboveground live C that goes to

                   maintenance respiration for crops

     CKMRSPMX(2) - maximum fraction of belowground live C that goes to

                   maintenance respiration for crops

     NO3PREF(1)  - fraction of N uptake that is NO3 for crops, currently not

                   being used

     CLAYPG      - number of soil layers used to determine water and mineral

                   N, P, and S that are available for grass/crop growth

     TMPGERM     - germination temperature for the growing degree day

                   submodel, will cause a FRST event when FRTCINDX = 3 or a

                   PLTM event when FRTCINDX = 4 or 5 (degrees C)

     DDBASE      - number of degree days required to trigger a senescence

                   (SENM) event for a perennial (FRTCINDX = 3), maturity and

                   harvest (HARV) for a non-grain filling annual

                   (FRTCINDX = 4), or to reach anthesis (flowering) for a

                   grain filling annual (FRTCINDX = 5 or 6)

     TMPKILL     - temperature at which growth will stop when using the

                   growing degree day submodel, will cause a SENM and LAST

                   event when FRTCINDX = 3 or a HARV and LAST event if

                   FRTCINDX = 4, 5, or 6, if the required number of thermal

                   units have not been accumulated prior to trigger a SENM or

                   a HARV event (degrees C)

     BASETEMP(1) - base temperature for crop growth, growing degree days will

                   accumulate only on days when the average temperature is

                   greater than the base temperature for the crop (degrees C)

     BASETEMP(2) - ceiling on the maximum temperature used to accumulate

                   growing degree days (degrees C)

     MNDDHRV     - minimum number of degree days from anthesis (flowering) to

                   harvest for grain filling annuals (FRTCINDX = 5 or 6)

     MXDDHRV     - maximum number of degree days from anthesis (flowering) to

                   harvest for grain filling annuals (FRTCINDX = 5 or 6)



For reference, here are the definitions for the other FRTC(*) parameters which

are also used in the new dynamic carbon allocation routines:

     FRTC(1) - fraction of C allocated to roots at planting, with no water or

               nutrient stress, used when FRTCINDX = 2, 4, 5, or 6

     FRTC(2) - fraction of C allocated to roots at time FRTC(3), with no

               water or nutrient stress, used when FRTCINDX = 2, 4, 5, or 6

     FRTC(3) - time after planting (months with soil temperature greater than

               RTDTMP) at which the FRTC(2) value is reached, used when

               FRTCINDX = 2, 4, 5, or 6



The FRTCINDX, FRTC(*), CFRTCN(*), and CFRTCW(*) parameters are used in the new

dynamic carbon allocation routines.  FRTCINDX is inserted into the crop

parameterization preceding the FRTC(1) parameter.  The FRTC(4), FRTC(5),

CFRTCN(1), CFRTCN(2), CFRTCW(1), and CFRTCW(2) parameters follow the FRTC(3)

parameter.



When converting from an existing Century/DayCent 4.0 CROP.100 file format to a

DayCent 4.5 CROP.100 file format the following rules will be used to set

default values for these parameters.

1.  If FRTC(1) = 0.0 in the Century/DayCent 4.0 crop parameterization assume

    this is a parameterization that should be set to use the Great Plains

    equation.

    Set FRTCINDX to 0.

2.  If FRTC(1) != to 0.0 in the Century 4.0 crop parameterization then we

    cannot make an assumption about what this parameterization represents.

    The user will be prompted to enter a 1 for a perennial plant, a 2 for an

    annual plant, a 3 for an annual grass using the growing degree day

    submodel, or a 4 for an annual crop using the growing degree day submodel

    to set the FRTCINDX value. 

In all cases FRTC(1), FRTC(2) and FRTC(3) will retain their original Century

4.0 values.  FRTC(4) will be set to 0.2, FRTC(5) will be set to 0.1, CFRTCN(1)

will be set to 0.4, CFRTCN(2) will be set to 0.25, CFRTCW(1) will be set to

the original Century 4.0 FRTC(1) value, and CFRTCW(2) will be set to the

original Century 4.0 FRTC(2) value.



The KMRSP(1), CKMRSPMX(1), and CKMRSPMX(2) parameters are used in the new

maintenance respiration routines.  These parameters are give the following

values:

     KMRSP(1)    - 0.00000

     CKMRSPMX(1) - 0.00000

     CKMRSPMX(2) - 0.00000



The NO3PREF(1) parameter is not being used by the model currently but is

included in this conversion utility for compatability with anticipated future

code changes.  The NO3PREF(1) parameter is given a default value of 0.25000.



The KMRSP(1), CKMRSPMX(1), and CKMRSPMX(2), and NO3PREF(1) parameters follow

the CO2IRS(1) parameter.



The CLAYPG parameter is added to each crop option in the crop.100 file

following the NO3PREF(1) parameter.  It is given a default value of 4.



The TMPGERM, DDBASE, TMPKILL, BASETEMP, MNDDHRV, and MXDDHRV parameters are

added to the end of each crop option in the crop.100 file following the CLAYPG

parameter.  These parameters are given default values of 10.0, 1400.0, -2.0,

10.0, 100.0, and 200.0 respectively.



The definition for the PRDX(1) parameter has been changed and each crop option

in the crop.100 file should have the value for PRDX(1) set to a default value

of 0.5.  New DayCent 4.5 PRDX(1) definition:

     PRDX(1) - coefficient for calculating potential aboveground monthly

               production as a function of solar radiation outside the

               atmosphere



------------------------------------------------------------------------------

FERT.100:



The FERT.100 file used by DayCent version 4.5 has 4 additional parameters

added to the end of each fertilizer option:

     NINHIB   - reduction factor on nitrification rates due to nitrification

                inhibitors added with the fertilizer

     NINHTM   - determines how long to simulate the effect of the nitrogen

	            inhibitor from the fertilizer addition

     FRAC_NH4 - the fraction of N fertilizer that is NH4+ (ammonium)

     FRAC_NO3 = the fraction of N fertilizer that is NO3- (nitrate)



Using a value of 1.0 for NINHIB parameter will have no effect on the

nitrification rate.  The reduction in nitrification rate will linger for 1 1/2

months after the fertilizer application.



The default value for these parameters:

     NINHIB   - 1.00000

     NINHTM   - 7.00000

     FRAC_NH4 - 0.75000

	 FRAC_NH3 - 0.25000



------------------------------------------------------------------------------

FIRE.100:



The FIRE.100 file used by DayCent version 4.5 has 11 additional parameters and

3 parameters that have had their "names" changed:

     FDFREM(3) - fraction of dead fine branches removed by a fire event

     FDFREM(4) - fraction of dead large wood removed by a fire event

     FRET(1,1) - fraction of C in the burned aboveground material (live

                 shoots, standing dead, and litter) returned to the system

                 following a fire event as charcoal in the passive SOM pool

     FRET(1,2) - fraction of N in the burned aboveground material (live

                 shoots, standing dead, and litter) returned to the system

                 following a fire event (NOTE: replaces fret(1))

     FRET(1,3) - fraction of P in the burned aboveground material live

                 shoots, standing dead, and litter) returned to the system

                 following a fire event (NOTE: replaces fret(2))

     FRET(1,4) - fraction of S in the burned aboveground material (live

                 shoots, standing dead, and litter) returned to the system

                 following a fire event (NOTE: replaces fret(3))

     FRET(2,1) - fraction of C in the burned dead fine branch material

                 returned to the system following a fire event as charcoal in

                 the passive SOM pool

     FRET(2,2) - fraction of N in the burned dead fine branch material

                 returned to the system following a fire event 

     FRET(2,3) - fraction of P in the burned dead fine branch material

                 returned to the system following a fire event

     FRET(2,4) - fraction of S in the burned dead fine branch material

                 returned to the system following a fire event

     FRET(3,1) - fraction of C in the burned dead large wood material returned

                 to the system following a fire event as charcoal in the

                 passive SOM pool

     FRET(3,2) - fraction of N in the burned dead large wood material returned

                 to the system following a fire event

     FRET(3,3) - fraction of P in the burned dead large wood material returned

                 to the system following a fire event

     FRET(3,4) - fraction of S in the burned dead large wood material returned

                 to the system following a fire event



The FDFREM(3), FDFREM(4), and FRET(1,1) parameters follow the FDFREM(2)

parameter.  The FRET(1,2) parameter replaces the FRET(1) parameter.  The

FRET(1,3) parameter replaces the FRET(2) parameter.  The FRET(1,4) parameter

replaces the FRET(3) parameter.  The remainder of the new FRET(*,*) parameters

follow the FRET(1,4) parameter.  The FRTSH and FNUE(*) parameters follow the

FRET(3,4) parameter.



The following default values are used for these parameters:

     FDFREM(3) - 0.30000

     FDFREM(4) - 0.20000

     FRET(1,1) - 0.10000

     FRET(1,2) - retains value of FRET(1) from original file

     FRET(1,3) - retains value of FRET(2) from original file

     FRET(1,4) - retains value of FRET(3) from original file

     FRET(2,1) - 0.00300

     FRET(2,2) - 0.20000

     FRET(2,3) - 0.00000

     FRET(2,4) - 0.00000

     FRET(3,1) - 0.00300

     FRET(3,2) - 0.20000

     FRET(3,3) - 0.00000

     FRET(3,4) - 0.00000



------------------------------------------------------------------------------

FIX.100:



The FIX.100 file used by DayCent 4.5 has 2 additional parameters:

     TEFF(4) - slope of line at inflection point

     PSECOC2 - controls the back flow from occluded to secondary P



The PSECOC parameter has been renamed PSECOC1 and retains its original

definition:

     PSECOC1 - controls the flow from secondary to occluded P



The PSECOC2 parameter follows the PSECOC1 parameter.



When running the conversion utility the PSECOC1 parameter retains the value

for PSECOC and the following default value is used for PSECOC2:

     PSECOC2 - 0.00000



DayCent 4.5 uses 4 coefficients in the equation for computing the temperature

effect on decomposition.  The TEFF(4) parameter is added to give us the

additional coefficient required to paramerterize the temperature equation.

The definitions for the TEFF(*) parameters are as follows:

     TEFF(1) - "x" location of inflection point

     TEFF(2) - "y" location of inflection point

     TEFF(3) - step size (distance from the maximum point to the minimum

               point)

     TEFF(4) - slope of line at inflection point



The TEFF(4) parameter is inserted in the FIX.100 file following the TEFF(3)

parameter.



When running the conversion utility the following default values are used for

the TEFF(*) parameters:

     TEFF(1) - 15.4000

     TEFF(2) - 11.7500

     TEFF(3) - 29.7000

     TEFF(4) - 0.03100



The PET calculation is now taking into account solar radiation outside of the

atmosphere and an approximated cloud cover based on temperature range.  As a

result of this change the FWLOSS(4) parameter in the FIX.100 file needs to be

rescaled.  A default value of 0.8 is now recommended for this parameter.



Due to the changes in the snow melting equation the following default values

will be entered for the TMELT(*) parameters:

     TMELT(1) - 0.00000

     TMELT(2) - 0.00200

TMELT(1) retains its original definition.  TMELT(2) has been redefined:

     TMELT(2) - coefficient used for calculating snow melt as a function of

                solar radiation outside the atmosphere



When modifying a monthly fix.100 file for use with DayCent the following

settings are recommended and will be used here when converting the file:

     ADEP(1)   = 10.0

     ADEP(2)   = 20.0

     ADEP(3)   = 15.0

     ADEP(4)   = 15.0

     ADEP(5)   = 30.0

     ADEP(6)   = 30.0

     ADEP(7)   = 30.0

     ADEP(8)   = 30.0

     ADEP(9)   = 30.0

     ADEP(10)  = 30.0

     ANEREF(3) = 1.0

     FWLOSS(1) = 1.0

     FWLOSS(2) = 1.0

     FWLOSS(3) = 1.0

     FWLOSS(4) = 0.8

     IDEF      = 1.0

     MINLCH    = 2.5

     OMLECH(3) = 1.9 (< 2.0)

     VLOSSE    = 0.0

     VLOSSG    = 0.0



------------------------------------------------------------------------------

TREE.100:



The TREE.100 file used by DayCent version 4.5 has 15 additional parameters:

     TFRTCN(1)   - maximum fraction of C allocated to fine roots under maximum

                   nutrient stress

     TFRTCN(2)   - minimum fraction of C allocated to fine roots with no

                   nutrient stress

     TFRTCW(1)   - maximum fraction of C allocated to fine roots under maximum

                   water stress

     TFRTCW(2)   - minimum fraction of C allocated to fine roots with no water

                   stress

     MAXNP       - maximum N/P ratio for leaves, used only when nelem >= 2

     KMRSP(2)    - the fraction of net primary production that goes to the

                   carbohydrate storage pool for trees

     FKMRSPMX(1) - maximum fraction of live leaf C that goes to maintenance

                   respiration for trees

     FKMRSPMX(2) - maximum fraction of live fine root C that goes to

                   maintenance respiration for trees

     FKMRSPMX(3) - maximum fraction of live fine branch C that goes to

                   maintenance respiration for trees

     FKMRSPMX(4) - maximum fraction of live large wood C that goes to

                   maintenance respiration for trees

     FKMRSPMX(5) - maximum fraction of live coarse root C that goes to

                   maintenance respiration for trees

     NO3PREF(2)  - fraction of N update that is NO3 for trees, currently not

                   being used

     TLAYPG      - number of soil layers used to determine water and mineral

                   N, P, and S that are available for tree growth

     TMPLFF      - temperature at which leaf drop will occur in a deciduous

                   tree type, degrees C

     TMPLFS      - temperature at which leaf out will occur in a deciduous

                   tree type, degrees C



The TFRTCN(*) and TFRTCW(*) parameters are used in the new dynamic carbon

allocation routines.  TFRTCN(1) is inserted into the tree parameterization

following the FCFRAC(5,2) parameter followed by TFRTCN(2), TFRTCW(1), and

TFRTCW(2).  The TFRTCW(2) parameter and precedes the LEAFDR(1) parameter.



When running the conversion utility the TFRTCN(*) and TFRTCW(*) parameters are

given the following default values:

     TFRTCN(1) - 0.40000

     TFRTCN(2) - 0.25000

     TFRTCW(1) - 0.36000

     TFRTCW(2) - 0.30000



The MAXNP, KMRSP(2), FKMRSPMX(1), FKMRSPMX(2), FKMRSPMX(3), FKMRSPMX(4), and

FKMRSPMX(5) parameters are used in the new maintenance respiration routines.

These parameters are give the following values:

     MAXNP       - 13.5000

     KMRSP(2)    - 0.00000

     FKMRSPMX(1) - 0.00000

     FKMRSPMX(2) - 0.00000

     FKMRSPMX(3) - 0.00000

     FKMRSPMX(4) - 0.00000

     FKMRSPMX(5) - 0.00000



The NO3PREF(2) parameter is not being used by the model currently but is

included in this conversion utility for compatability with anticipated future

code changes.  The NO3PREF(2) parameter is given a default value of 0.50000.



The MAXNP, KMRSP(2), FKMRSPMX(1), FKMRSPMX(2), FKMRSPMX(3), FKMRSPMX(4), and

FKMRSPMX(5) parameters follow the SITPOT parameter.



The SITPOT parameter is now dynamic and will be computed as a function of

average annual precipitation.  The SITPOT parameter value read from the

TREE.100 file is used as a multiplier for tuning this equation.  This

conversion utility will set all of the SITPOT parameter values in a TREE.100

file to 1.0 so there will be no multiplicative effect.



The definition for the PRDX(2) parameter has been changed and each tree option

in the tree.100 file should have the value for PRDX(2) set to a default value

of 0.5.  New DayCent 4.5 PRDX(2) definition:

     PRDX(2) - coefficient for calculating potential monthly forest

               production as a function of solar radiation outside the

               atmosphere



The PRDX(3) parameter is no longer being used and has been removed from the

tree.100 file.



The equation for computing tree basal area has been changed therefore BASFCT

is given a a default value of 1.0.



The TLAYPG parameter is added to the end of each tree option in the tree.100

file.  It is given a default value of 6.



The TMPLFF and TMPLFS temperature values are added to the end of each tree

option in the tree.100 file.  They are given default values of 7.0 and 10.0

respecitively.



------------------------------------------------------------------------------

<SITE>.100:



There have been three parameters added to this file.

     ROCK   - fraction of rock in soil (0.0 - 1.0)

     PRECRO - the amount of monthly rainfall required in order for runoff to

              occur (cm) (used by monthly Century only)

     FRACRO - the fraction of the monthly rainfall, over PRECRO, which is lost

              via runoff (0.0 - 1.0) (used by monthly Century only)



The ROCK parameter is added following the CLAY parameter and is used to modify

AFIEL and AWILT values if SWFLAG is not equal to 0.  Set this parameter value

to 0.0 to run a simulation with no rock effect on field capacity and wilting

point values.



The PRECRO and FRACRO parameters are added following the STORMF parameter and

are used in place of hard coded values for computing the runoff amount in

monthly Century.



The following default values are assigned to these parameters by the

conversion utility:

     ROCK   - 0.00000 

     PRECRO - 8.00000

     FRACRO - 0.15000



The equation for computing the non-symbiotic soil N fixation has been changed.

This change requires a modification of the EPNFS(*) parameter values.  The

following are the default values used for the EPNFS(*) parameters:

     EPNFS(1) - 30.0000

     EPNFS(2) - 0.01000



When modifying a monthly <SITE>.100 file for use with DayCent the following

settings are recommended and will be used here when converting the file:

     STORMF = 0.0

     SWFLAG = 0.0



The WD?LIG parameters are obsolete and need to be removed from the <SITE>.100

file if necessary.



------------------------------------------------------------------------------

*.SCH (schedule file) changes:



The user now has the option of adding comment lines to the top of a schedule

file.  All of the comment lines must start with a # character and must be

stored at the top of the schedule file.  There is no blank line permitted

between the last comment line and the schedule file header line containing the

start year information.



Example DayCent 4.5 schedule file with no comment lines:

1             Starting year

2002          Last year

...



Example DayCent 4.5 schedule file with comment lines:

# comment line 1

# comment line 2

# comment line 3

1             Starting year

2002          Last year

...



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The user also has the ability to simulate a shift in soil pH content if

desired.  If the value for PHSYS as read from the schedule file is greater

than 0 then the next line in the schedule file contains the start year for the

pH shift to begin.  The optional multiplier on pH can be used to scale the

amount of pH in the soil, for example to simulate liming experiments.  If the

pH shift is not being modeled a value of 0 should be read in for the PHSYS

variable.



Valid values for the pH scalar option are:

      0 - No scalar used

      1 - Use pH scalars



Example DayCent 4.5 schedule file header excerpt with no pH shift:

-1             CO2 Systems

0              pH shift



Example DayCent 4.5 schedule file header excerpt with pH shift:

-1             CO2 Systems

1              pH shift

1990



The conversion utility will modify an existing Century/DayCent 4.0 schedule

file to add the header line for no pH shift.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We have also added an option to simulate soil surface temperature warming

experiments where the soil surface temperature is warmed without an increase

in the minimum and maximum air temperature values if desired.  The soil

surface warming option is implemented in the same manner the CO2 effect and

the pH shift effect options.  If the value for stsys as read from the schedule

file header is greater than 0 then the next line in the schedule file header

contains the start year for the soil surface warming and the following line

contains the amount to warm the soil surface temperature in degrees C.



Valid values for the soil warming option are:

      0 - No soil warming

      1 - Simulate soil warming



Example DayCent 4.5 schedule file header excerpt with no temperature warming

experiment:

-1             CO2 Systems

0              pH shift

-1             Soil warming



Example DayCent 4.5 schedule file header excerpt with temperature warming

experiment:

-1             CO2 Systems

0              pH shift

1              Soil warming

1990

0.5



The conversion utility will modify an existing Century/DayCent 4.0 schedule

file to add the header line for no soil warming experiment.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We have added options to allow the user to use a multiplier on the N

additions, FERT and/or atmospheric N deposition, and/or OMAD additions to the

simulation to scale these additions up and/or down as desired.  The

scalars are stored in the nscale.dat for FERT and/or atmospheric N deposition.

The OMAD scalars are stored in the OMADin.dat file.  These two files are

optional and if the scalars are not used you do not need to have these files

in your working directory.



Valid values for the N input scalar option are:

     0 - No scalar used

     1 - Use scalar on FERT options only

     2 - Use scalar on atmospheric N deposition only

     3 - Use scalar on both FERT options and atmospheric N deposition

If the value read from the schedule file header for the N input scalar is

greater than 0 then the next line in the schedule file header contains the

year to start reading and using the N scalar values for the nscale.dat file.



Valid values for the OMAD input scalar option are:

     0 - No scalar used

     1 - Use OMAD scalars



Example DayCent 4.5 schedule file header excerpt with no N input or OMAD input

scalars:

-1             CO2 Systems

0              pH shift

-1             Soil warming

0              N input scalar option

0              OMAD input scalar option



Example DayCent 4.5 schedule file header excerpt with N input and OMAD input

scalars:

-1             CO2 Systems

0              pH shift

-1             Soil warming

0              N input scalar option

1975

0              OMAD input scalar option

1975



The conversion utility will modify an existing Century/DayCent 4.0 schedule

file to add the header lines for no N input or OMAD input scalars.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We have added options to allow the user to use scalars on the weather inputs

to simulate climate change scenarios.  The scalars are stored in the 

tmaxscale.dat, tminscale.dat, and precscale.dat for modifying minimum

temperature, maximum temperature, and/or precipitation values respectively.

The temperature scalars are addends while the precipitation scalars are

multipliers.



Valid values for the weather input scalar option are:

     0 - No scalars used

     1 - Use scalars for minimum temperature only

     2 - Use scalars for maximum temperature only

     3 - Use scalars for both minimum and maximum temperatures

     4 - Use scalars for precipitation only

     5 - Use scalars for minimum and maximum temperatures and precipitation



Example DayCent 4.5 schedule file header excerpt with no climate scalars:

-1             CO2 Systems

0              pH shift

-1             Soil warming

0              N input scalar option

0              OMAD input scalar option

0              Climate scalar option



Example DayCent 4.5 schedule file header excerpt with climate scalars:

-1             CO2 Systems

0              pH shift

-1             Soil warming

0              N input scalar option

0              OMAD input scalar option

5              Climate scalar option

1990



The conversion utility will modify an existing Century/DayCent 4.0 schedule

file to add the header lines for no climate scalars.



------------------------------------------------------------------------------

SITEPAR.IN:



The following parameters have been added to the SITEPAR.IN file for

parameterizing a water table simulation:

     drainlag       - number of days between rainfall event and drainage of

                      soil (-1=computed)

     watertable[12] - 0 = no water table, 1 = water table

     hpotdeep       - hydraulic water potential of deep storage layer

     ksatdeep       - saturated hydraulic conductivity of deep storage layer

                      (cm/sec)

These variables follow the hours_rain variable.



The texture input value read from the sitepar.in file is no longer being used.

The texture value used by the decomposition subroutine is computed based on

the weighted average of sand in the top 3 soil layers.



The texture input parameter has been replaced by the tbotmn and tbotmx

paramters.  The line containing these parameter values follows the fraction of

N fertilizer that is nitrate, frac_no3_fert, line.

     tbotmn - minimum temperature for bottom soil layer for year (degrees C)

     tbotmx - maximum temperature for bottom soil layer for year (degrees C)

Both parameter values are entered on the same line, separated by a space.



The dmp input parameter has been added to this file.  It follows the tbotmn

and tbotmx parameters.  This parameter is a time step, or damping, correction

factor that relates to how fast the heat gets into/out of the soil.

     dmp - damping factor for calculating soil temperature by layer



The timlag parameter has been added to this file.  This parameter represents

the time lag, in days, from the beginning of the year to the occurrence of the

coolest temperature at the bottom of the soil profile.  The timlag parameter

follows the damping factor for calculating soil temperature by layer 

parameter.

     timlag - time lag, in days, from the beginning of the year to the

              occurrence of the coolest temperature at the of the bottom soil

              profile



Add the Ncoeff parameter to this file.  This parameter represents the minimum

water/temperature limitation coefficient for nitrification.  This parameter

value is used to modify the value for the amount of NH4 that is converted to

NO3 due to nitrification.  It follows the timlag parameter.

     Ncoeff - minimum water/temperature limitation coefficient for

              nitrification



The start day and end day added to this file allow the user to turn off the

respiration restraint on denitrification during the days of the year the fall

between the given days.  These parameters follow the entries for the soil

layers comprising the very deep depths.



The fraction of N fertilizer that is ammonimum and the fraction of N

fertilizer that is nitrate values have been removed from this file and added

to the FERT.100 file.



A new nitrification N2O adjustment factor parameter has been added to this

file.  This factor is a used as a multiplier on the nitrification rates and

should be given a value between 0.0 and 1.0.

     N2Oadjust - nitrification N2O adjustment factor (0.0-1.0)



We are no longer using the shallow, intermediate, deep, and very deep soil

depths to calculate a weighted average value to be used when calculating

transpiration.  As a result the sitepar.in file has been modified to remove

the input that defines these layers.