PNNL

Abstract

Tropical cyclones (TCs) induce substantial upper-ocean mixing and upwelling, leading to a cooling of the sea surface. In this study, we explore changes in TC-induced cold wakes along the United States (U.S.) East and Gulf coasts over 1982-2020. Our study shows a significant increase in TC-induced SST cooling of about 0.23C near the U.S. East Coast over this period. However, for the U.S. Gulf coast, trends in the magnitude of TC-induced SST cooling are insignificant. Analysis of the large-scale oceanic environments indicate that the increasing TC-induced cold wakes near the Atlantic coast have been predominantly caused by the cooling of subsurface waters in that region. This upper-ocean change is attributed to the enhancement of surface pressure gradient across land-sea boundary and the associated increase in upwelling favorable winds over there. Further analysis with the climate models reveals the important role of anthropogenic forcings in driving these changes in the atmospheric circulation along the U.S. East coast.