Time and spatial variability of sea surface temperature in the Gulf of California

Abstract

Fourteen years of satellite images (1983–1996) are used to examine the variability of sea surface temperature (SST) in the Gulf of California. The study focussed on the semiannual, annual and interannual scales and on the average. On average, SST decreases from the mouth to the head and its variability increases. The annual scale is responsible for most of the temporal variability, which oscillates in phase with minor north-south variations. The northern gulf shows the formation of warm anticyclonic eddies during winter and cold cyclonic eddies during summer. The spring transition shows a cyclonic eddy closer to the mainland side of the gulf; the autumn transition shows a not well-defined anticyclonic eddy. The SST around the island region is always colder than the rest of the gulf. The lateral variability in the central and southern regions is associated with upwelling phenomena. The semiannual and annual amplitudes increase to the north by a factor of two with respect to the southern region. On the interannual scale, the 1988–1989 and 1992–1993 events reach all the gulf. Both events appear first in the south and island regions, and the signals are more intense at the islands than the rest of the gulf. This behavior has not been reported before. The 1985, 1987 and 1990 events show a "normal" evolution, i.e., the warm waters appear in the south and gradually progress into the gulf.