Troubleshooting Your Simulation Configuration

Considerations when importing a Century 4 site file:

The major change in the site parameters from verion 4 to 5 is addition of layered soil. After importing your Century 4 site file, edit the soil layer thickness, texture and bulk density values, as well as NLAYER and NLAYPG, to reflect the real soil on the site. More information on the layered soil structure is in the section Soil Physical Structure Submodel. A new algorithm for estimating depth distribution of soil organic C may have difficulties with an improperly configured physical soil. See the section Depth Distribution of Soil Carbon for more details on this algorithm.

The site mneumonic retains that name for compatibility with Century 4, but now can be 20 characters in length. You may want to modify the original name to be more descriptive. For example, rather than a cryptic Century 4 name of "SVNA", you can name your site "Savanna".

New fields available in the Century 5 site files, available in the Site Parameters Editor, are:

Site Type
Press the "Change" button in the Site Parameters Editor to select from crop, grass, tree, and savanna site types.
Site Description
Contains descriptive text about this site. Maximum length is 80 characters.

New parameter catagories in the Century 5 sites apply to erosion and deposition:

Initial lower layer pools
These are the initial values for the C, N, P, and S pools for the soil region below the simulation layer. If you do not specify values, but use erosion or deposition, default values are supplied when the first erosion or deposition event is encountered. See the section Erosion and Deposition for more details on the algorithms. The section Site Parameters for Lower Layer Pools Initial Values describes these parameters.
Erosion and deposition
These parameters affect the pools which are eroded. See the section Site Parameters for Erosion Pools Loss Factors for more information.

Considerations when importing a Century 4 management file:

In Century 4, management blocks are linear and repetitive sequences of events. In Century 5, blocks are organized into block definitions, and block instances. Definitions specify a sequence of events, and are identified by name and a unique event sequence. Instances of the blocks specify the use of the block in the simulation time.

Upon importing a Century 4 management schedule, identical blocks are combined, and blocks are numbered (See the dialog page "Define Blocks" in the Management Editor.) If there is a comment string at the beginning of the Century 4 block, the string is appended to the name. After importing, you may want to give your blocks names reflecting their contents (e.g., "corn-soybean"). Don't forget to save your imported schedule as a Century 5 management scheme!

You can examine your imported management schedule with a verification process, to check for actual or potential problems. A "Verify" button at the bottom of the Management Editor performs the verification check, and results are written to the message window.

New fields available in the Century 5 management scheme, available in the "Simulation Information" dialog page, are:

Contains descriptive text about this management scheme. Maximum length is 80 characters.
File name for erosion output
If simulating erosion and you want to save the eroded amounts, specify a file name with an optional path. The netCDF file name extension, "nc", will be added. See the section Erosion File for more details.
File name for deposition input
If simulating deposition, you will specify the input file name here. This file is generated from an erosion simulation. See the section Erosion File for more details.

When you get an error message during a simulation:

First, see the list of error messages and their explanations in the section Century Error Messages. If you have just imported a Century 4 site or management file, see the sections above regarding considerations upon importing.

If you think you have found a real bug in the Century or CMI operation, please send detailed information to the Century help desk. See Contacting NREL for more information.

See Also

Century Error Messages
Site Parameters
Editing Site Management