Orography

Orography is the average height of land, measured in geopotential meters[?], over a certain domain. In geoscientific models[?], such as general circulation models, orography defines the lower boundary (except where there is ocean, of course). Because orography is spatially averaged, for example the height of the Himalaya mountains will depend on horizontal resolution. The higher the horizontal resolution, the better the orography will follow the actual terrain.