'Dynamic sea surface topography' is the average difference between the actual surface of the
Earth and a
geoid. It is caused by a steady state
ocean current field in the
ocean which in turn is caused by climatologic
winds and
temperature transport in the oceans. The dynamic sea surface topography is usually derived from
ship-going
measurements of
temperature and
salinity at depth. In recent years,
satellite altimetry systems have made it possible to measure sea surface topography directly.