Surface Water Exchange Between the Continental Shelf and the Deepwater Region of the Gulf of Mexico

Cross-shelf water exchange is the mechanism that transport properties such as nutrients, oxygen, larvae, pollutants, etc. from coastal areas to oceanic zones and vice-versa. This exchange is hard to measure because the flows which favor it are weak, mostly ageostrophic and due to flow instabilities. In this study, we analyzed observed velocities from drifters and current meters from the period between 1993 and 2018 all around the shelf and slope of the Gulf of Mexico. We investigate the regions and seasons at which water parcels in the continental shelf are more likely to leave towards the deep region and vice-versa. Based on these probabilities, we also show the areas where there is a preferential direction for this exchange. The two shallow regions where water parcels are more likely to leave the shelf are the southeastern Bay of Campeche independent of the season, and the southwestern Texas shelf during Summer. Water in the deep region of the northwest corner of the gulf is most likely to enter onto the shelf throughout the year. Some ideas of the reasons why there are regions where the exchange is enhanced in one or the other direction will be discussed.