Warm Core Eddy Response to the Passage of Hurricane Harvey

Warm core eddies (WCEs) in the Gulf of Mexico (GoM) are originally shed from Loop Current and translate westward around 2-6 km/day. After several months they reach the western GoM and dissipate through interaction with the shelf slope. WCEs have significant impact on the GoM, they influence circulation, outer shelf currents, oil spill dispersion, gas hydrate stability, larval fish distribution, chlorophyll dispersal, river discharge exit pathway, and tropical cyclone intensity. There are several recorded occurrences of hurricanes passing over WCEs, these mainly focus on how WCEs boost hurricane strength because of their large ocean heat content, or how the surface cooling is restrained due to reduced thermocline entrainment. However, few studies have approached hurricane-WCEs interaction with an eddy-centric view yet there is a need to understand the holistic and longer-term changes to eddies when they are disrupted by extreme surface forcing.

In this study, we use Argo Floats and Marine Copernicus analysis dataset to investigate Harvey’s impact on the WCE heat content. The results show that Harvey broke the WCE in three. Using eddy boundary analysis we found that Harvey caused the ocean heat in the upper 300 m of the WCE to propagate through the northern box boundary (a rectangle fit around the eddy) and propagate southward through the northern eddy boundary. This indicates a potential heat source for the hurricane Harvey’s intensification and the reason why the eddy was broken after the hurricane passed by.

Keywords: Hurricane Harvey, Eddy Response, Western Gulf of Mexico