Increased sea surface cooling from hurricanes observed along the Southeast Coast of the United States in recent decades

Utilizing satellite observations and ocean reanalysis datasets, researchers have analyzed the change in sea surface cooling induced by hurricanes and the corresponding ocean-atmosphere environment along the Gulf and Southeast coastal regions of the United States.

The study, published in the journal Geophysical Research Letters, found the magnitude of sea surface cooling increased by about 0.20 °C in the nearshore regions of the Southeast Coast over the period 1982–2020. However, there was no significant change in storm-induced cooling along the Gulf Coast, which highlights the regional nature of these responses to global warming.

To gain a mechanistic understanding of the physical processes responsible for the enhanced hurricane cold wakes near the Southeast United States, investigators used ocean reanalysis datasets. An examination of the oceanic environment revealed that the increased magnitude of cold wakes along the Southeast Coast has likely resulted from a cooling of subsurface waters in that region. Further analysis suggests that the latter can be attributed to an increase in pressure gradient across the land–sea boundary.

This results in a strengthening of alongshore winds, which in turn increases upwelling of colder subsurface water. The findings from the Coupled Model Intercomparison Project Phase 6 (CMIP6) models indicate that anthropogenic forcings are likely driving these changes in the atmospheric circulation along the Southeast Coast. These findings shed light for the first time on how interactions between hurricanes and upper-ocean conditions are changing under a warming climate near the U.S. Southeast Coast.