Selectable Variations

Sometimes a dataset may contain multiple related geographic layers or rasters. Each raster will provide a single value (usually a number) for each grid cell in the raster. However, there might be a raster in the dataset generated from the GFDL Global Climate Model (GCM), and anther which is the same except it was generated from the PCM Global Climate Model, and a thrid based on the CCSM model, for three total. Or there might be rasters for each of two greenhouse gas emission scenarios, two total. If there were variants all combinations of three models and two scenarios, there would be six rasters total.

Sometimes there are rasters for only one variation within a category. For example, there might be only one Multiyear Range. In that case, the Multiyear Range will be described here, but no choice within that category is needed or possible.