Tracking Loop Current Eddies in the Gulf of Mexico Using Satellite-Derived Chlorophyll-a

Abstract

During the period of 2018–2022, there were six named Loop Current Eddy (LCE) shedding events in the central Gulf of Mexico (GoM). LCEs form when a large anticyclonic eddy (AE) separates from the main Loop Current (LC) and propagates westward. In doing so, each LCE traps and advects warmer, saltier waters with lower Chlorophyll-a (Chl-a) concentrations than the surrounding Gulf waters. This difference in water mass permits the study of the effectiveness of using Chl-a from satellite-derived ocean color to identify LCEs in the GoM. In this work, we apply an eddy-tracking algorithm to Chl-a to detect LCEs, which we have validated against the traditional sea surface height(SSH) based eddy-tracking approach with three datasets. We apply a closed-contour eddy-tracking algorithm to the SSH of two model products (HYbrid Coordination Ocean Model; HYCOM and Nucleus for European Modelling of the Ocean; NEMO) and absolute dynamic topography (ADT) from altimetry, as well as satellite-derived Chl-a data to identify the six named LCEs from 2018 to 2022. We find that Chl-a best characterizes LCEs in the summertime due to a basin-wide increase in the horizontal gradient of Chl-a, which permits a more clearly defined eddy edge. This study demonstrates that Chl-a can be effectively used to identify and track LC and LCEs in the GoM, serving as a promising source of information for regional data assimilative models. Citation: Trott, C.B.; Subrahmanyam, B.; Hiron, L.; Zavala-Romero, O.

Cite

@article{trott2024tracking,
  title = {Tracking Loop Current Eddies in the Gulf of Mexico Using Satellite-Derived Chlorophyll-a},
  author = {Trott, Corinne B. and Subrahmanyam, Bulusu and Hiron, Luna and Zavala-Romero, Olmo},
  year = {2024},
  doi = {10.3390/rs16122234},
  url = {https://doi.org/10.3390/rs16122234},
}

Topics

• Ocean