Surface circulation in the Gulf of California in summer from surface drifters and satellite images (2004–2006)

Abstract

Surface drifters released in the Gulf of California between June 2004 and August 2006 are used to describe the surface circulation in late spring and summer. In the June to September mean, there was a poleward coastal current on the shelf and slope of the mainland side of the Gulf, with mean speed 0.3 m/s; it reached the northern Gulf and joined the cyclonic circulation typical of this zone in summer. In the western half of the southern Gulf, the drifters presented recirculating currents that are due to mesoscale eddies that appear to dominate the surface circulation in summer. In June 2004, the coastal current presented an enhancement event with mean speed around 0.60 m/s and maximum 0.80 m/s. It took 20 days for a particular drifter to travel the 1000 km from the Gulf entrance to the head. This strengthening of the coastal current was apparent in chlorophyll a and SST satellite images, the drifters following closely the intrusion of warm, chlorophyll-poor surface water from outside the Gulf. The drifters and the satellite images suggest that the current-enhancement event lasted less than a month. This mesoscale event was linked with a mesoscale remote forcing in the tropical Pacific coast and with a mesoscale local forcing of the wind. These events seem to occur every year, and are probably important in carrying organisms and properties from the entrance to the whole length of the Gulf.

Environmental Variability and Oceanographic Dynamics of the Central and Southern Coastal Zone of Sonora in the Gulf of California

“…They can be generated by the coupling processes of macroscale atmospheric phenomena and regional mesoscale events, which seem to occur each year [14].…”

“…All of these phenomena have been the result of atmospheric forcing interaction in the Pacific where seasonal winds (with flux toward the southeast in winter and toward the northwest in summer) induced a significant barotropic variability in kinetic energy associated with gyres and upwelling, as well as in energy associated with fluctuations of the current force as mentioned by Badan-Dangón [15], Stammer and Wunsch [6] and Lavín et al [14].…”

“…Moreover, gyres retain and transport organisms and enrichment processes as upwelling and filaments that favor the habitat of a great number of organisms [14,[24][25][26].…”

“…entrance to the whole length of the GC [14], which cause important seasonal variability in the mean field of variables, such as SST and Chl-a, impacting the GC ecosystem, one of the most diverse marine biological communities in the world and a strategic region for marine fisheries in Mexico, ideal for the use of SST and Chl-a satellite images for its environmental characterization.…”

Applying SPOT Images to Study the Colorado River Effects on the Upper Gulf of California

“…It is the habitat of some endangered endemic species, such as the totoaba (Totoaba macdonaldi) and the vaquita marina (Phocoena sinus), which are estuarine-dependent [10]. The decrease in river discharges has converted the Colorado River Delta into a negative estuary with hypersaline water, thus altering the habitat of these species [10,11].…”