Investigation of ocean environmental variables and their variations associated with major Loop Current eddy-shedding events in the Gulf of Mexico

Abstract

The eddy kinetic energy (EKE) variability associated with 26 major Loop Current eddies (LCEs) in the Gulf of Mexico from 1994 through 2019 was investigated. We employed 3D multivariate observation-based ARMOR3D monthly ocean analyses of salinity, temperature, and geostrophic velocity field data. In addition, we used ERA5 wind data, the fifth generation of the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric global climate reanalysis, to analyze internal and external forcing processes affecting the evolution of these LCEs. The energy analysis was performed to understand the role of barotropic (BT) and baroclinic (BC) instabilities and their associated energy conversion mechanisms in EKE generation. Our results suggest that BT instabilities are the primary source of EKE variability in the upper water column of the LC system. Furthermore, BT was positively correlated with Yucatan Channel (YC) transport during these major LCE shedding events. YC transport plays a significant role in energy conversion from mean kinetic energy to EKE, Loop Current growth, and generation of LCEs. BC instability was inversely correlated with buoyancy frequency, and a decrease in stratification triggers the development of BC instability, which favors eddy shedding. An eddy shedding index (ESI) was developed to quantify EKE evolution. Major LCE shedding occurs when ESI ≥0.46.