Basics: Geogrid

The purpose of GEOGRID is to define the simulation domain(s), and interpolate various terrestrial data sets to the model grids.

The simulation domain(s) are defined using information specified by the user in the "share" and "geogrid" sections of the WPS namelist. Please see our Best Practices WPS Namelist page for detailed explanations of these and other namelist.wps parameters, in addition to recommended practices.

In namelist.wps, multiple columns are used for multiple domains. If you use 3 columns, but set max_dom to 2, the last column will be ignored. NOTE: Not all parameters have multiple columns, e.g., dx and dy.

By default, in addition to computing latitude and longitude for every grid point, geogrid will interpolate soil categories, land use category, terrain height, annual mean deep-soil temperature, monthly vegetation fraction, monthly albedo, maximum snow albedo, and slope category to the model grids.

 

STEPS to Run GEOGRID

**Note: This is just a brief description of the basic steps - meant to help you understand the process. If you currently have no data, or simulation you would like to run, you can wait until you get to the 'case studies' section, later, to try to follow along.

1. Download the terrestrial input data
2. Edit the &share and &geogrid sections of the namelist.wps file for your particular domain set-up.

Run plotgrids.ncl to ensure your domain is in the right location before running geogrid.exe ncl util/plotgrids.ncl

3. Run geogrid.exe (output is in the format of 'geo_em.dxx.nc' - one file for each domain)

./geogrid.exe

Basics – UNGRIB