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To obtain the geopotential height (h) in metres (of the land and sea surface or at particular heights in the atmosphere), simply divide the geopotential by the Earth's gravitational acceleration, which has a fixed value of 9.80665 m/s2 in the IFS. This geopotential height is relative to the geoid over land and the mean sea level over ocean - for more information see ERA5: data documentation - spatial reference systems.
Geometric height
The geometric height or altitude (alt) is given by:
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