The GIS link

CGMS does not use or need a GIS to produce results. However, a GIS is necessary for a meaningful presentation of the output, and is also indispensable for the initial creation of the database. The GIS link is formed by the concept of the EMU and the grid. Interpolated meteorological data are stored per grid cell, simulated yields are stored per EMU. In the database table GRID describes the grids. The number that identifies each grid cell provides a link to a GIS, e.g. an ArcInfo ‘coverage’ or an ArcView ‘theme’. The EMU is stored as a combination of grid number, soil mapping unit number and the code (or number) identifying the administrative unit in which the EMU lies. These identifiers can be used to provide the link to the GIS.
 

GIS requirements

To create the GRID and the ELEMENTARY_MAPPING_UNIT tables, several GIS data sets are required. CGMS does not impose the use of any particular geographic or co-ordinate system. However, all geographic data used in the same CGMS installation should be compatible. As an example, the JRC currently uses a Lambert-Azimuthal projection for each coverage used in CGMS.