Enhancement of subduction/obduction due to hurricane-induced mixed layer deepening

Ventilation, including subduction and obduction, in the North Pacific is re-examined, based on SODA outputs and the Eulerian definition. The annual subduction rate averaged from 2001 to 2004 is estimated at 49.8 Sv, whereas the annual obduction rate is 26.7 Sv.Furthermore, the annual subduction/obduction rate enhancement induced by tropical cyclones in the North Pacific, defined as the difference between the annual subduction/obduction rate for the cases including the mixed layer depth perturbations induced by tropical cyclones and that for the cases without the perturbations, is estimated. Based on SODA outputs and the mixed layer deepening obtained from a hurricane-ocean coupled model, the annual tropical cyclone-induced subduction rate enhancement averaged from 2001 to 2004 is estimated at 4.4 Sv and the obduction rate enhancement 5.2 Sv, and such enhancement is mainly concentrated in the latitudinal band from 10°N to 30°N.