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For users experienced in Metview, there is a built-in function called mvl_geopotential_on_ml.
Geopotential height
In ERA5, and often in meteorology, heights (the height of the land and sea surface, or specific heights in the atmosphere) are not represented as geometric height, or altitude (in metres above the spheroid), but as geopotential height (in metres above the geoid, which is represented by the mean sea level in ERA5). Note, that ECMWF usually archive the geopotential (in m2/s2), not the geopotential height.
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