Upper Ocean Response to Tropical Cyclones

摘要

The long-term scientific goal of the research is to understand key physical processes governing the upper ocean's thermal and momentum response to the passage of tropical cyclones over nearinertial time scales. The investigation examines the evolving 3-dimensional upper ocean structure excited by the passage of tropical cyclones using a blend of in situ and satellite- based measurements, theoretical treatments, and numerical simulations. Specific objectives of the study are: i) To examine the importance of the density structure and geostrophic currents on both the upper ocean response and the forced near-inertial motions including the propagation of energy from the mixed layer into the thermocline; ii) To determine the atmospheric forcing structure and its impact upon the upper ocean response; and iii) To assess the relative roles of advection and mixing processes on the evolving 3-dimensional ocean mixed layer response. The approach combines aircraft-based oceanic observations from Gilbert with MMS mooring and survey data to document the steady-state and transient upper ocean current response in the presence of a warm core eddy. These profiler data are blended with the ship-based CTD measurements to resolve the salinity and density differences between the eddy and Gulf common water in the western Gulf of Mexico. Upon removal of this steady-state component, the transient response is isolated using nearinertial models in storm coordinates (Shay et al., 1989). Velocity profiles are WKB-scaled to determine the excess clockwise-rotating energy and multiplied by the vertical group velocity for each wavenumber to determine the downward internal wave flux.