Relative Impacts of Local and Remote Forcing on Tropical Cyclone Frequency in Numerical Model Simulations

Abstract

AbstractNumerical experiments are carried out to explore the impacts of local and remote forcing on the interannual variability of tropical cyclone (TC) frequency. The first two groups of experiments focus on the regional simulations of Atlantic TCs, and the lateral boundary conditions and sea surface temperature (SST) are specified to investigate the relative importance of remote and local forcing. The results suggest that remote processes outside the North Atlantic, particularly extratropical processes, play an important role in modulating Atlantic TC frequency and that the remote impacts may exceed the impacts of local SST in some years. The total TC frequency in the northern tropics is explored in the third group of experiments. In contrast to the North Atlantic, tropical SST plays a dominant role in modulating the total TC frequency in the northern tropics. The difference may help to explain the uncertainties in the projections of future Atlantic TC frequency.