North Pacific storm track response to the mesoscale SST in a global high-resolution atmospheric model

The response of the North Pacific storm track to the mesoscale sea surface temperature (SST) in winter is investigated via a global high-resolution atmospheric model. A simulation forced by eddy-resolving SST is compared with a simulation in which the mesoscale SST is filtered out. The results show that removing the mesoscale SST could greatly influence the storm track in the free atmosphere, with a significant decrease of approximately 20% in the local region and a southward shift downstream over the eastern North Pacific. Compared with those in previous studies, the responses of the storm track seem to be independent from models. The underlying mechanism is that changes in the boundary layer induced by mesoscale SST lead to convergence at the surface through pressure adjustment, forcing a secondary circulation along Kuroshio and Oyashio confluence region (KOCR). Then the winter mean vertical eddy fluxes are greatly suppressed over KOCR after removing the mesoscale SST, transporting less heat and moisture into the free atmosphere. Furthermore, the response of baroclinicity and baroclinic energy conversion was investigated, which bears much resemblance with the changes of storm track, indicating the important role on the response of storm track to mesoscale SST.