Extended Abstract (184K)14D.2
Processes affecting the ocean's feedback on the intensity of a hurricane
Robert L. Korty, MIT, Cambridge, MA
In this study, we examine the contribution of individual, dynamic processes to the ocean's feedback on the intensity of a hurricane. Previous coupled modeling studies have found that the cooling of the mixed-layer by turbulent entrainment of thermocline water can have a marked impact on the intensity of a hurricane, as the sea surface temperature is cooled in a storm's immediate wake. We use a coupled model consisting of an axisymmetric hurricane model and a three-dimensional, four-layer ocean model to investigate the role of dynamics in the ocean that may affect the rate of entrainment. Specifically, we test the importance of nonlocal processes such as Ekman pumping, horizontal advection, and pressure gradients to hurricanes that are uniformly translating, accelerating, and decelerating. Our results show that, in this model, nonlocal dynamics do not significantly alter the magnitude of the ocean's feedback for any storm moving at a modest pace. Only storms moving exceedingly slowly (translation speeds less than about 3 m/s) are sensitive to the inclusion of these dynamics. Upwelling enhances the rate of entrainment beneath the core of the hurricane for slowly moving storms; excluding this process from the model resulted in an overestimation of the maximum sustained winds by about 5%. We conclude that entrainment dominates the ocean's feedback to the intensity of a hurricane, and nonlocal dynamics do not play a significant role in altering its magnitude.
Session 14D, Tropical Cyclone Air-Sea Interaction (Parallel with Sessions 14A, 14B, and 14C)
Thursday, 2 May 2002, 2:00 PM-3:30 PM
Previous paper Next paper