Effect of Caribbean Water Incursion into the Gulf of Mexico derived from Absolute Dynamic Topography, Satellite Data, and Remotely – sensed Chlorophyll-a

Juan Delgado, Universidad Autonoma de Baja California, Instituto de Investigaciones Oceanologicas, Ensenada, SO, Mexico, Joël Sudre, LEGOS/CNRS, SYSCO2, Toulouse, France, Sorayda Tanahara, Universidad Autonoma de Baja California, Ensenada, BJ, Mexico, Ivonne Montes, Instituto Geofísico del Perú, Lima, Peru, Jose Martin Martin Hernandez-Ayon, Universidad Autónoma de Baja California, Instituto de Investigaciones Oceanologicas, Ensenada, BC, BJ, Mexico; Universidad Autonoma de Baja California, Investigador del Instituto de Investigaciones Oceanologicas, Ensenada, Mexico and Alberto Zirino, University of California, San Diego, Scripps Institution of Oceanography, La Jolla, CA, United States
The dynamics of the Loop Current (LC) and the detached Loop Current eddies (LCE’s) dominate

the Gulf of Mexico's (GoM) surface circulation and transport Caribbean water (CW) into the

GoM. In this work, 25-years (1993-2017) of daily satellite data are used to investigate the

variability of these physical processes and their effect on chlorophyll-a (Chl-a) concentrations

from 1998-2017 including temporal changes, mean differences, and regional concentration

tendencies. Physical variables analyzed are absolute dynamic topography (ADT), oceanic currents,

and wind stress. From the ADT and oceanic current monthly climatologies, it is shown that there

is an annual intrusion of the CW with an inward incursion that starts in spring, peaks in the summer

(reaching to 26.58 ̊N and 88.32 ̊W) and then retreats in winter. Minimum surface Chl-a

concentrations (<0.08 mg m-3) are found during the summer-autumn period inside the region of

maximum incursion of the CW; the opposite is observed during the winter period when the Chl-a

concentrations were at a maximum, e.g., >0.14 mg m-3. The three-year running averages of ADT

40-cm isoline reproduce qualitatively the climatological pattern of 25 years showing that before

2002 the CW was less intrusive. This suggests that from 2003 onward, larger volumes of

oligotrophic waters from Caribbean Sea have invaded the western GoM and reduced mean surface

Chl-a concentrations. A direct comparison between the 1998-2002 and 2009-2014 periods

indicates that, in the latter time interval, Chl-a concentration above waters deeper than 250 m has

decreased significantly.