Air Mass Modification over the Eastern Gulf of Mexico as a Function of Surface Wind Fields and Loop Current Position

Abstract

The effects of surface wind patterns and Loop Current position on surface distributions of latent and sensible heat fluxes in the eastern Gulf of Mexico are demonstrated. Mean monthly fields of thew fluxes computed from data collected during February 1975 and February 1976 are computed. The wind fields of February 1975 and 1976 are decomposed into two different modes, a north-wind mode associated with winter outbreaks of dry cold continental air masses and a trade-wind mode associated with advection from the south of warm moist maritime air. The distributions of sensible and latent heat fluxes are different for each mode with both beat heat fluxes considerably larger over the northern Gulf, in particular, during times of the northerlies. However, during these two months, trade-wind days are more numerous and the mean monthly flux patterns reflect this pre-ponderance. A simple model of the effect of extreme Loop Current configurations and the associated sea surface temperature distributions on air parcels traversing the Gulf below the inversion layer is presented. Total changes in air parcel temperature and specific humidity are shown to depend on the configuration of the Loop Current. Parcels which traverse the Gulf and cross the U.S. coastline between Louisina and Florida during the time of a deep northern Loop intrusion have 1.3°C higher temperatures and 1.0 g kg?1 greater specific humidities than parcels which crow the Gulf during a shallow Loop intrusion.