Bottom Mixing Enhanced by Tropical Storm‐Generated Near‐Inertial Waves Entering Critical Layers in the Straits of Florida

Abstract

AbstractTropical storms and hurricanes frequently pass over the Straits of Florida, energizing the near‐inertial wave (NIW) field in the strait. Two ship‐based surveys, which were launched shortly after storms, observed velocity shear bands over the western slope of the strait—clear signatures of NIWs. Also, the hydrographic measurements demonstrate the formation of a slantwise critical layer (where isopycnals are parallel with bathymetry) over the western slope, which is known to be a trapping zone for NIWs. A realistic simulation of the Straits confirms the emergence of NIWs under a tropical storm, which is accompanied by inertially modulated bottom‐enhanced mixing over the western slope. The mechanism driving the mixing is that the storm‐generated NIWs radiate downward from the core of the Florida Current, reflect off the eastern slope, and enter the slantwise critical layer over the western slope; upon entering, wave trapping, and amplification lead to the enhanced mixing.