The ocean's effect on the intensity of tropical cyclones: Results from a simple coupled atmosphere-ocean model

A coupled hurricane-ocean model was constructed from an axisymmetric hurric ane model and a three-layer ocean model. If the hurricane moves at constant speed across the ocean a statistically steady state (in a reference frame moving with the storm) is reached after a few days of simulation time. The steady-stare intensity of the hurricane is strongly affected by the interac tion with the ocean. This interaction with the ocean can be described as a negative feedback effect on the hurricane's intensity and is called "SST fe edback." A large set of numerical experiments was performed with the couple d model to deduce systematically the dependence of the amplitude of the SST feedback effect on a set of model parameters. In the coupled model the SST feedback effect can reduce the hurricane's int ensity by more than 50%. Only in cases of rapidly moving storms over deep o ceanic mixed layers is the SST feedback effect of minor importance. These r esults cast a new light on the role of the ocean in limiting hurricane inte nsity.