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• the average elevation above mean sea level (MSL). This is taken from the smoothed model orography.
• the fraction of land. This is used to assess the proportions of each grid square used by HTESSEL and FLake to derive heat, moisture and momentum fluxes. 
• the fractional cover of different vegetation types.   This is used by HTESSEL to derive the different proportions of heat, moisture and momentum fluxes over the land.

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• smooth true orography, particularly in rugged mountainous areas where there are large variations in altitude over short distances.  Mountain peaks may be under-represented and narrow valleys may not be represented at all.
• local effects can be under-identified where there are small scale variations in true or model orography, even where relatively low in altitude. 
• lead to "topographic ripples" over adjacent sea/large lakes, which decay with offshore distance, and which are most prominent where there are steep-sided high mountains nearby.

See also selection of grid points for meteograms and model representation of orography.

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