Seasonal upwelling on the Western and Southern Shelves of the Gulf of Mexico
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An 8-year database of sea surface temperature (SST), 7 years of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color images, wind fields, and numerical model results are analyzed to identify regions and periods of coastal upwelling on the western and southern shelves of the Gulf of Mexico. On the seasonal scale, it is found that on the Tamaulipas, Veracruz, and southwestern Texas–Louisiana shelves there are upwelling favorable winds from April to August, when southeasterly winds are dominant and cold SST anomalies associated with upwelling are observed along their coasts. However, during summer, values of chlorophyll-a concentration are lower than those in autumn and winter, which are high due to advection of old bloom biological material from upstream. During winter, there is a cold front on the Tamaulipas shelf produced by advection of cold water from the Texas–Louisiana shelf and not due to upwelling. On the eastern Campeche Bank, persistent upwelling is observed due to favorable winds throughout the year with cold SST and large chlorophyll-a content along the inner shelf from May to September. On the Tamaulipas shelf, the summer upwelling delays the annual SST peak until September, while in most of the Gulf SST peaks in August. This difference is due to the end of the upwelling favorable wind conditions and the September seasonal current reversal.
KeywordsGulf of Mexico Coastal upwelling Coastal circulation AVHRR SST
This project was funded by CONACYT Grant SEP-2003-C02-45634, UNAM Grants PAPIIT IN122005-3 and PAPIIT IN-1158042004. The authors would like to thank the SeaWiFS Project and the Distributed Active Archive Center (Code 902) at the Goddard Space Flight Center, Greenbelt, MD 20771, for the production and distribution of the data. These activities are sponsored by NASA’s Mission to Planet Earth Program. We would like to thank Rosario Romero-Centeno, who made important suggestions to improve this manuscript, and Paul Martin and Alan Wallcraft for their assistance with the NCOM; Olivia Salmerón, Erik Márquez, and Ranulfo Rodriguez processed the SeaWiFS and SST data. The numerical modeling work was sponsored by the ONR Secretary of the Navy grant to J. J. O’Brien, and by NASA Physical Oceanography.
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