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

Juan Antonio Delgado, Joël Sudre, Sorayda Tanahara, Ivonne Montes, José Martin Hernandez-Ayon, Alberto Zirino
2019 Ocean Science Discussions  
<p><strong>Abstract.</strong> The dynamics of the Loop Current (LC) and the detached Loop Current eddies (LCE's) dominate the Gulf of Mexico's (GoM) surface layers' circulation transporting Caribbean water (CW) into the GoM. In this work, 25-years (1993&amp;ndash;2017) of daily satellite data are used to investigate the variability of these physical processes and their effect on chlorophyll-<i>a</i> (Chl-<i>a</i>) concentrations from 1998&amp;ndash;2017 including temporal changes, mean
more » ... nges, 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-<i>a</i> concentrations (&amp;lt;0.08 mg m<sup>&amp;minus;3</sup>) 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-<i>a</i> concentrations were at a maximum, e.g., >0.14 mg m<sup>&amp;minus;3</sup>. 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-<i>a</i> concentrations. A direct comparison between the 1998&amp;ndash;2002 and 2009&amp;ndash;2014 periods indicates that, in the latter time interval, Chl-a concentration over waters deeper than 250 m has decreased significantly.</p>
doi:10.5194/os-2019-58 fatcat:uncfnofpgfb4hjf46vznye7jdq