DayCent5: NOx Submodel

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N Trace Gas submodel: Sequence of steps

1. Calculate redistribution factors for NH4, CO2, NO3 among soil layers
2. Nitrification
   1. Soil temperature, pH effects on nitrification.
   2. Calculate NH4 from NO3
3. Partition Nitrate
   1. Calculate a factor (>= 1) for the NOx flux based on recent rain events and snowpack.
   2. Calculate fractions of new NO3 that is converted to N2O and NO.
   3. Redistribute NO3 among soil layers
4. Denitrification
   1. soil nitrate (NO3-) concentration each layer
   2. soil (N2+N2O) denitrification fluxes each layer
   3. Dentrification each layer:
      1. calculate normalized diffusivity in aggregate soil
      2. calculate water filled pore space threshold
      3. calculate CO2 correction factor when WFPS has reached threshold
      4. calculate NO3, CO2, water filled pore space effects on denitrification
      5. calculate N fluxes (N2 + N2O)
      6. NO3, water filled pore space effects on N2 : N2O
      7. calculate N2 : N2O, and N2 and N2O fluxes
   4. Reduce nitrate in soil by the amount of N2, N2O that is lost.
5. Partition denitrification fluxes
   1. NO flux is taken from available NH4 and N2O
6. Redistribute NH4 and NO3 among soil layers

References

The following papers are the major source for the N subsystems in DayCent5.

Del Grosso, S. J.; Parton, W. J.; Mosier, A. R.; Ojima, D. S.; Kulmala, A. E.; Phongpan, S. 2000. General model for N2O and N2 gas emissions from soils due to denitrification. Global Biogeochem. Cycles 14, No. 4, 1045-1060.

Parton, W. J.; Holland, E. A.; Del Grosso, S. J.; Hartman, M. D.; Martin, R. E.; Mosier, A. R.; Ojima, D. S.; Schimel, D. S. 2001. Generalized model for NOx and N2O emissions from soils. J. Geophys. Res. Vol. 106 , No. D15 , p. 17,403-17,419.

See Also