Estimation of heat and salt fluxes in a Loop Current Eddy using microstructure glider based observations

Abstract:

An anticyclonic Loop Current Eddy (LCE) was surveyed for the first time with a microstructure turbulence package during a glider mission in fall 2016. The eddy exhibited a well-defined structure of several scalar fields, and showing a distinctive warm core and a salty patch beneath it. We suggest that this is the result of subtropical underwater being transported by that LCEs into the Gulf of Mexico. The heat and salt anomalies resulted in an additional 1.84 * 10¹⁹ J and 4.59 * 10¹¹ kg of salt, when compared to the surrounding waters. Microstructure observations were used to estimate TKE dissipation rates and eddy diffusivities, which in turn were used to estimate heat and salt fluxes from the eddy and to identify double diffusion prone areas. The vertical heat and salt fluxes beneath the eddy core were found to be governed by shear mixing while favorable conditions for thermohaline intrusions were observed on the flanks of the eddy. This double diffusive process is likely responsible for most of the fluxes of heat and salt from the eddy, and suggest a lifespan of such an eddy to be on the order of 1.5 years.