Martínez-Díaz-de-León, A.; Castro, R.; Santamaría-del-Ángel, E.; Pacheco-Ruiz, I., and Blanco-Betancourt, R. 2013. Sea surface heat fluxes and fortnightly modulation of the surface temperature within Ballenas Channel, Gulf of California.
Sea surface temperature (SST) and meteorological information from July 2004 to July 2005 for Alcatraz Bay, which is located within the Ballenas Channel (BC) in the Gulf of California, was used to investigate the occurrence of sudden and drastic drops of almost 7°C in the SST. This occurrence was previously observed in the analysis of SST time series that were recorded simultaneously in six bays along the western coast of the BC. Contrary to previous observations, wind speed showed a weak seasonal variability, with a directionality that departed from the typical monsoonal behavior of wind throughout the Gulf. Although the presented ocean surface heat flux calculations were obtained from coastal data, the results are in agreement with previous estimates, as the net heat flux mainly went into the sea for the whole year, with an annual mean heat gain of 197 W m−2. SST analysis showed that along with a marked seasonal cycle, there are also four main periods of variability: quarter-diurnal, semidiurnal, diurnal, and fortnightly, corresponding to the main timescales of variability induced by tides. The sudden and drastic drops observed in the SST are clearly related to the intensification of the vertical mixing that is induced by tides and are enhanced at a fortnightly tidal period. MODIS-Aqua SST imagery was used as a supporting, indirect evidence of the mesoscale representativeness of our results, which we suggest can be considered valid for the whole BC.