The geoid deviates from the ellipsoid by an amount on the order of tens of metres - from -106m in southern India, to +85m in Iceland. This has effects on satell

The geoid deviates from the ellipsoid by an amount on the order of tens of metres - from -106m in southern India, to +85m in Iceland. This has effects on satellite orbits as well as on ocean surface, although that is affected further by ocean circulation (meaning it is not locally flat) and subsequently by tides.