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Free keywords:
Climate change; Climate models; Ocean models; Transport; Tropical cyclones
Abstract:
In this paper the interplay between tropical cyclones (TCs) and the Northern Hemispheric ocean heat transport (OHT) is investigated. In particular, results froma numerical simulation of the twentieth-century and twenty-first-century climates, following the Intergovernmental Panel on Climate Change (IPCC) twentiethcentury run (20C3M) and A1B scenario protocols, respectively, have been analyzed. The numerical simulations have been performed using a state-of-the-art global atmosphere-ocean-sea ice coupled general circulation model (CGCM) with relatively high-resolution (T159) in the atmosphere. The CGCM skill in reproducing a realisticTCclimatology has been assessed by comparing themodel results fromthe simulation of the twentieth century with available observations. The model simulates tropical cyclone-like vortices with many features similar to the observed TCs. Specifically, the simulatedTCs exhibit realistic structure, geographical distribution, and interannual variability, indicating that the model is able to capture the basic mechanisms linking the TC activitywith the large-scale circulation. The cooling of the surface ocean observed in correspondence of the TCs is well simulated by themodel.TCactivity is shown to significantly increase the polewardOHT out of the tropics and decrease the polewardOHT fromthe deep tropics on short time scales. This effect, investigated by looking at the 100 most intense Northern Hemisphere TCs, is strongly correlated with the TC-induced momentum flux at the ocean surface, where the winds associated with the TCs significantly weaken (strengthen) the trade winds in the 5°-18°N(18°-30°N) latitude belt.However, the induced perturbation does not impact the yearly averaged OHT. The frequency and intensity of the TCs appear to be substantially stationary through the entire 1950-2069 simulated period, as does the effect of the TCs on the OHT. © 2011 American Meteorological Society.
