Influence of the interannual variability of tropical cyclones on the western Gulf of Mexico circulation

Measurements of 4-year currents on the western shelf of the Gulf of Mexico (GM) show that there is a strong influence in the summer circulation from the ocurrence of tropical cyclones and easterly waves. In the absence of tropical cyclones weak currents are observed, with a more frequent northwestward direction and predominant upwelling conditions. When tropical storms or hurricanes cross the Bay of Campeche, strong southeastward currents and downwelling conditions develop, increasing the bottom temperature on the shelf by several degrees. Measurements over the Veracruz Coral Reef System (VCRS) show that during 2010, hurricane Alex, (June 25 to July 1st), crossed the GM generating northerly winds along the western shelf of the GM. Later, by July 7th, a low pressure system developed on the western Caribbean which became tropical depression No 2, and by July 17th another low pressure system over the western Caribbean and the Yucatan Peninsula moved northwestward generating northerly winds over the VCRS. These events were favored by relatively low pressure over the Gulf of Tehuantepec that developed Tehuanos and northerly winds over the western GM. During these events, strong southerly currents and downwelling conditions were observed.