Agulhas Eddies: A Synoptic View Using Geosat ERM Data

Abstract

Abstract Warm core rings formed in the, Agulhas Retroflection transfer water from the Indian Ocean to the South Atlantic. In an attempt to measure the strength of this exchange, a combination of satellite altimeter and hydrographic data are used to examine Agulhas eddy paths and decay rates in the South Atlantic. Because the surface dynamic height of a warm core eddy is higher than surrounding waters, the rings are visible in satellite altimeter measurements. Over 20 Agulhas eddies have been tracked from maps of anomalous sea surface height (SSH) derived from the Geosat Exact Repeat Mission (ERM) dataset. The correlation (r2) of dynamic height referenced to 2000 dbar and anomaly SSH for one coincidentally sampled area is 97% within an Agulhas eddy, dropping to a fraction of that outside of it, indicating that the SSH anomaly signal is a reliable measure for strong features like Agulhas eddies. The sizes and distribution of the Agulhas eddies in the ERM record compare favorably with those in recent hydrogr...