Oceanic thermal forcing of North Atlantic tropical cyclones

The relationship between North Atlantic tropical cyclone (TC) peak intensity and subsurface ocean temperature is investigated in this study using atmospheric and ocean reanalysis data. It is found that the peak intensity of basin-wide strong TCs (Categories 4 and 5) is positively correlated with subsurface ocean temperature in the extratropical North Atlantic. A possible physical mechanism is that subsurface ocean temperature in the extrat-ropical North Atlantic can affect local sea surface temperature (SST); on the other hand, the moisture generated by the warming SST in the extratropical North Atlantic is transported to the main region of TC development in the tropics by a near-surface anticyclonic atmospheric circulation over the tropical North Atlantic, affecting TC peak intensity. Moreover, coastal upwelling off Northwest Africa and southern Europe can affect subsurface ocean temperature in the extratropical North Atlantic. Therefore, the peak intensity of strong TCs is also found to be directly correlated with the water temperature in these two upwelling regions on an interdecadal timescale.