Improved understanding of Intense Current Dynamics from combined use of Envisat ASAR and GOCE data.
Johannessen, Johnny A.1; Chapron, Bertrand2; Collard, Fabrice2; Raj, Roshin1; Tournadre, Jean2

Synoptic wide coverage high-resolution estimation of ocean surface velocity is readily available from the Envisat ASAR-detected Doppler shift measurements that has emerged from mid 2007 to March 2012. Building on more than 1000 ASAR acquisitions over the greater Agulhas Current, gridded maps of high-resolution (12.5 km x 12.5 km) Doppler-derived ocean surface velocities are established. The robust and consistent results confirm an intense and persistent manifestation of the greater Agulhas Current. Both the mean and the seasonal variability of the Agulhas Current is examined and compared to similar fields of surface velocities derived from the combined use of GOCE derived MDT and altimeter based sea level anomalies for the same period. This new combined Doppler and GOCE based product is shown to strengthen the study and monitoring of intense current dynamics in combination with surface drifter data and sea surface temperature measurements. As such it is expected that Sentinel-1 together with altimetric missions (including Sentinel 3) can bring this promising detection capabilities towards regular monitoring.