Tropical  Cyclones  -­‐  Ocean  feedbacks:  Effects  on  the  Ocean  Heat  Transport   as  simulated  by  a  High  Resolution  Coupled  General  Circulation  Model

Tropical cyclones (TCs) activity and their relationship with the Northern hemispheric Ocean Heat Transport (OHT) is investigated with a focus on the Western North Pacific. The analysis has been performed using 20C3M (20th Century) and A1B (21st Century) IPCC scenario climate simulations obtained running a fully coupled atmosphere-ocean-seaice coupled global model, with high- resolution in the atmosphere (T159). The model is able to simulate tropical cyclone-like vortices with many features similar to the observed TCs. The simulated TC activity exhibits realistic structure, geographical distribution and interannual variability, indicating that the model is able to reproduce the major basic mechanisms that link the TC activity with the large scale circulation. The TC-induced ocean cooling is well represented and the TCs activity increases significantly the poleward OHT out of the tropics, but also increases the heat transport into the deep tropics on the time scale of weeks. This effect, investigated looking at the 100 most intense Northern hemisphere TCs, is strongly correlated to the TC-induced momentum flux at the surface of the ocean: the winds associated to the TCs significantly weaken the Trade Winds in the 5-18oN latitude belt and reinforce them in the 18-30oN band. A comparison between two simulation with and without TCs effect on the wind stress over the ocean will be also done in order to better understand the role of TCs on the annually averaged OHT. TCs frequency and intensity appear to be substantially stationary through the whole 1950-2069 period. Also the effect of the TCs induced OHT (TCiOHT) does not significantly change during the simulated period.PublishedTaipei, Taiwan3.7. Dinamica del clima e dell'oceanoope