What can we learn from Global Altimetry/Hydrography comparisons?

Differences and complementarities between altimeter and hydrographic data are studied to describe the sea level and ocean circulation variations in terms of steric and non-steric contributions. Altimeter sea level anomalies (SLA) and hydrographic dynamic height anomalies (DHA) agree remarkably well. They also reveal, however, systematic large-scale differences in several areas of the Pacific and Indian oceans that are related to a barotropic, Sverdrup-like, response of the ocean to wind forcing. In addition, the use of the two data sets provides a good estimation of the partition between barotropic and baroclinic modes needed for data synthesis or assimilation studies.