Upper-ocean circulation patterns in the northern Gulf of California, expressed in Ers-2 Synthetic Aperture Radar Imagery

Abstract

ERS-2 Synthetic Aperture Radar (SAR) frames were collected over the northern Gulf of California during winter 1999. The frames, presented here as a single composite image (100 x 300 km), express a mesoscale meander or eddy-like feature, approximately 80 km wide, located close to the peninsula of Baja California. The eddy is expressed as bright, concentric bands that curve in an anticyclonic direction. The location and dimensions of the eddy are in very good agreement with the winter circulation of the northern Gulf of California described by Lavín et al. (1997), from the analysis of direct observations using satellite-tracked drifters and hydrographic surveys. The SAR image also depicts other smaller, cyclonic eddy-like features, located close to the mainland, which may be associated with the general circulation induced by the anticyclonic eddy. SAR images, together with the reduced number of in situ observations, can provide new and valuable information about the mesoscale circulation of the upper ocean in the Gulf of California, even when cloud cover prevents the use of other remote sensors, such as infrared radiometers and visible imaging systems.