depth_below_geoid

The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. (The volume enclosed between the geoid and the sea floor equals the mean volume of water in the ocean). In an ocean GCM the geoid is the surface of zero depth, or the rigid lid if the model uses that approximation. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. "Depth_below_X" means the vertical distance below the named surface X. rdf:langString