SHIP AND SATELLITE-OBSERVATIONS OF CHLOROPHYLL STOCKS IN INTERACTING CYCLONE-ANTICYCLONE EDDY PAIRS IN THE WESTERN GULF-OF-MEXICO

When anticyclonic eddies shed by the Loop Current of the Gulf of Mexic o reach the western margin of the gulf, they influence the surface cir culation over the continental slope and rise. Of particular interest i s the generation of cyclone (cold-core)-anticyclone (warm-core) pairs when aging Loop Current eddies interact with the continental margin. I n this paper we describe the physical and biological characteristics o f these cyclone-anticyclone pairs. Our objective was to determine how eddy pairs affect the distribution of phytoplankton in the region and how satellite ocean color measurements are applicable to tracing of th e eddies. We present shipboard data collected between 1980 and 1982 on the hydrography, chlorophyll stocks, and nutrient concentrations of e ddy pairs in the western Gulf of Mexico and compare these data with co astal zone color scanner (CZCS) images collected during the time frame of the cruises. Surface pigment concentrations followed a seasonal cy cle, with low concentrations (0.05-0.1 mg m-3)found within cyclones an d anticyclones from April through early November and higher concentrat ions (>0.1 mg m-3) found in the winter. CZCS pigment concentrations we re locally high in the flow confluence of cyclone-anticyclone pairs. T he CZCS imagery shows that some cyclone-anticyclone geometries transpo rt high-chlorophyll shelf water seaward at least 100-200 km off-shelf.