Summer generation of the Southern Gulf of California eddy train

Ocean color and sea surface temperature satellite-observations show the existence of a series of anticyclonic eddies along the axis of the southern Gulf of California (SGOC). To investigate the summer generation of these eddies, a regional version of the HYbrid Coordinate Ocean Model (HYCOM) has been configured for the GOC and has been nested inside the global model. A suite of experiments, using the nested GOC model, was developed and used to isolate the effects of the local wind and the effects of the oceanic remote forcing on the generation of the SGOC eddies. The results indicate that the local wind is not essential for the generation of these eddies rather it is the oceanic remote forcing. In the SGOC the monthly variability of the currents and sea surface height is mainly due to the deterministic near-coastal poleward eastern boundary currents (PEBC). The interaction of the PEBC with the topographic irregularities (the capes at Topolobampo and Cabo Lobos and the ridges extending offshore from the entrance of the San Lorenzo and Sinaloa Rivers) generates the SGOC eddies. The northward upper-ocean transport induced by the PEBC includes two maximums, one in May-June and the other in December. During the summers of 1999 and 2004 the PEBC were intensified by the arrival of equatorially-originated downwelling coastally-trapped-waves (CTWs), which contributed to the generation of the SGOC eddies. The summer 2004 CTW increased the northward upper-ocean transport by similar to 2 Sv. This particular CTW was measured by several tide gauges located along the coast.