Tropical wave-induced oceanic eddies at Cabo Corrientes and the Maria Islands, Mexico

[1] TOPEX/Poseidon and ERS-2 satellite altimeter observations and the 1/16 degrees Naval Research Laboratory (NRL) Layered Ocean Model (NLOM) show the existence of anticyclonic eddies in the Cabo Corrientes - Maria Islands region off the Mexican West Coast. Analysis of the results demonstrates that: ( 1) The Cabo Corrientes - Maria Islands region is characterized by mean poleward coastal currents, driven by local wind forcing. ( 2) The local currents are intensified by the arrival of baroclinic downwelling coastally trapped waves (CTWs), generated in the equatorial Pacific. ( 3) Anticyclonic eddies are generated as the intensified local currents pass cape-like features in the coastline or shelf-break geometry. ( 4) From 1979 to 2001 the CTWs generated an average of 2.35 (2.5) Cabo Corrientes (Maria Islands) anticyclonic eddies per year. ( 5) The formation of eddies varies interannually, increasing ( decreasing) during El Nino ( La Nina) years. Comparison of a variety of numerical simulations, which include different dynamics and/or different wind forcing and/or different topographic effects, suggests that bottom topography, local wind, and baroclinic instabilities are not essential for the eddy generation. It is ( a) the capes at Cabo Corrientes and the Maria Islands and (b) the strong transient events associated with the CTWs that are essential to the formation of these newly recognized eddies.