Hurricane influence on the oceanic eddies in the Gulf Stream region.

Abstract

The Gulf Stream region (GSR) represents an area of robust oceanic eddies, active hurricanes, and more importantly, frequent encounters between the two phenomena. However, the direct impact of the intense storms on the eddy field has seldom been comprehensively examined. Here based on a multi-year analysis of eddy energy changing rate, we demonstrate that hurricanes enhance cyclonic eddies but weaken anticyclonic ones by injecting potential vorticity into the ocean. Such effects are not only pronounced immediately following hurricane-eddy encounters, but also retained for extended periods within large eddies that have long lifespans. Consequently, the variation of the annual mean energy and vorticity of the eddy field exhibits a high correlation with hurricane intensity. It can thus be argued that hurricanes over the GSR play an important role in driving the long-term variation of the underlying eddy field, thereby affecting ocean circulation and climate.