Loop Current Entrainment and Advection of Phytoplankton from the Yucatan Shelf into the Southern Gulf of Mexico

Katharine Weathers, Northern Gulf Institute, Mississippi State University / NOAA NCEI, Stennis Center, MS, United States and Jeremy David Wiggert, The University of Southern Mississippi, Division of Marine Science, Stennis Space Center, MS, United States
Phytoplankton blooms on the Yucatan shelf are associated with uplifted slope water (known as Yucatan Upwelling Water), which brings colder, more nutrient-rich water, to the near surface through topographical driven processes. The blooms that result can be detected using remotely sensed ocean color. The Loop Current, which begins in the Yucatan Channel, can have high velocity flow near the Yucatan Continental Shelf. If this near-shore flow coincides with an upwelling event, the resulting phytoplankton bloom can be advected offshore into the open Gulf of Mexico. In this study, remotely sensed advection of phytoplankton blooms resulting from the upwelling system along the Yucatan Peninsula by the Loop Current system is explored. Utilizing sea surface height anomaly from NASA’s Jet Propulsion Laboratory and MODIS-Aqua ocean color data, northward advection of shelf waters with elevated chlorophyll concentrations via Loop Current entrainment is apparent. Surface currents drawn from third degree Ocean Surface Currents Analyses – Real time (OSCAR) are also examined to provide detail on the Loop Current path and surrounding current field during chlorophyll advection events identified in the ocean color data. Over the ocean color era from SeaWiFS on, there are numerous examples of such events that act to inject critical forage into the open waters of the southern Gulf of Mexico. A summary of such events from through 2012 has been developed to provide an understanding of seasonal variability. A detailed analysis of an example from summer 2012 for which supporting in situ data are available will be presented.