Spatio-Temporal Evolution of Upper Ocean Signature from Space and Surface Current Monitoring
Collard, Fabrice1; Chapron, Bertrand2; Johannessen, Johnny3; Kudryavfsev, Vladimir4

Wide Swath direct measurement of ocean surface velocities from space using SAR doppler shifts has proved to be possible with ENVISAT ASAR. Over the Gulf stream or the Agulhas regions, the so-called supersites, monitoring of surface current could then be derived using both instantaneous and temporal averages. Yet, for more global applications as well as to improve the temporal samplings, a single satellite mission is not enough, and strategies must build on the synergetic use of various satellite missions. Already, several altimeter measurements are helping to derive sea topography slope as a signature of the geostrophic component of ocean currents. Surface winds from scatterometers, SARs, but also passive microwave instruments, can further provide information on Ekman component of surface current. From these sets of medium-resolution observations, Sea Surface Temperature gradients from IR and microwave sensors can further provide higher resolution direct signatures of meso-to sub-meso scale upper ocean circulation. More regionaly, advection of local upper ocean tracers such as ocean color variability or sea surface roughness modulations, can provide a complementary information on meso to sub-meso scale surface current gradients. Merging these different sources of information in a dynamically consistent manner is a challenge that will benefit from the increasing number of ocean observing plateforms at international scale. Using heterogeneous sensors, they can indeed provide, when used in synergy, the high temporal sampling frequency required to monitor meso to sub-meso scale ocean surface currents.