Version 5 of the Century agro-ecosystem model represents a major change in the technical aspects of the model implementation, and includes new algorithms and structures for the physical soil, erosion, deposition, and depth distribution of organic C. Century 5 also includes the current cumulative set of bug fixes to Century's algorithms, easier and quicker access to simulation results, and a graphical user interface with which to configure and run your simulations.
Important new features in Century 5 include:
| Feature | More Information |
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Object-oriented architecture implemented in C++.
Object oriented architecture allows for extending the model's problem domain, and provides a common code base for monthly, daily, and gridded versions of the model. (Note: The daily and gridded versions are not yet available.) The entire code base, including the graphical user interface, is designed and implemented to be portable to any Microsoft Windows™ and Unix or Linux platform. Using C++, you can extend part or all of the Century model to use your own algorithms. One example of extending Century5 is our IRC project. |
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Use of the netCDF file library.
The netCDF file format provides platform-portability for site, management, parameter and output files, and the safety of a structured file format. Century can import Century 4 site (*.100) and management (*.sch) files. Output files can be in either netCDF or ASCII CSV formats. |
NetCDF Web Site |
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A dynamic layered soil structure with algorithms to manage soil layers. A site can be initialized with up to ten soil layers. Each layer is defined by thickness, texture, bulk density, and water content. During a simulation, the number of layers can be reduced to as little as one, through erosion, or increased to any number of layers, through depositon. Soil algorithms include erosion, deposition, homogenization and division of layers, and calculations for soil properties and pools across layers (whole or fractional layers.) In addition, the bulk density and thickness of the soil layers comprising the simulation depth (20 cm) are adjusted with changes in organic C content as simulated by Century (version 5.3.3 and later). |
Soil Physical Structure Submodel |
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New algorithms for erosion and deposition. Erosion pool amounts can optionally be saved in an erosion output file. Eroded pools can become deposited material in the simulation for an adjacent site. |
Erosion and Deposition |
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Water submodel fixes. Century 5 includes a number of fixes to problems in calculating runoff and soil water content. Fixes include a bug in the version 4 loop timing caused the precipitation and temperature data to be used offset by one month from the actual simulation month, and an error in which calculated plant-available water included only water in the simulation layer rather than the rooting depth. Runoff is now calculated as a 2nd-order equation whose coefficients are specified in the site parameters. These changes may have a substantial effect on simulation results relative to Century 4 due to greater water availability. |
Soil Water Submodel Changes |
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New algorithm for estimating total organic C in the soil profile.
Soil organic C is distributed over depth in the physical soil according to an exponential density distribution of organic C which decreases with depth. New output variables include total profile C and total C below the simulation layer. |
Implementation of an Exponential Depth Distribution of Organic C (pdf format) |
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Enhanced Land-Use Management The capabilities of the site management have been enhanced to provided new management events, including deposition. The structure of the management algorithms has been modified so additional events can be easily added. |
Management Events |
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Century Model Interface CMI is an interactive tool in which you can edit your site parameters, create and modify your management schedules, and run the simulation. Both CMI and the command-line Century programs can import Century 4 site (*.100) and management (*.sch) files. Using CMI you can create and edit your configuration preference files, and view the current simulation configuration before you run it. Messages generated during a simulation are displayed in a window. Simulations in progress can be cancelled. |
The Century Model Interface |
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Configurations for locations of site and management files and work directories. You can specify directory or folder locations for where you keep related site and management files, and where you want your simulation to write output files. Create and edit your configuration in the Century Model Interface. Save your preferences in one or more initialization files, and have Century and CMI read in the file when it starts. |
Initializing the Simulation Environment |
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Extensive HTML-based documentation and help. The Century manual, updated for version 5, along with additional documentation for the Century Model Interface and the new algorithms, is available both online and as a Microsoft HTML Help file. |
Documentation in Microsoft HTML Help format.
Online HTML documents |
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Simulation results can be stored in your choice of file formats. You can save your simulation results in ASCII CSV format, which is easily imported into your favorite spreadsheet program, or in netCDF format, which provides a structured, platform-portable binary file format. |
Century Simulation Results |
This document was last modified 2006 March 06