Marine heatwaves can strengthen hurricanes

Kyeong Park, professor and head of the Department of Marine and Coastal Environmental Science at Texas A&M-Galveston, and colleagues have had their work published in Nature Communications.

The team examined Hurricane Michael, the first Category 5 hurricane on record to impact the Florida Panhandle, in October 2018. Prior to Hurricane Michael, Tropical Storm Gordon in early September mixed cold bottom water with warm surface water, lowering the surface water temperature and increasing the capacity of absorbing more heat.

During the subsequent atmospheric heatwave, the water column could absorb more heat energy resulting in a marine heatwave, which later was used to strengthen Hurricane Michael to a Category 5 storm. Hurricane Michael became much stronger than was forecasted because it did not take into account this compound effect.

"During summer in the ocean, solar energy increases air temperature and surface water temperature so much that the entire water column -- from surface to bottom -- cannot absorb heat from the atmosphere," Park said.

Water in the Gulf of Mexico in the summer months is especially prone to these conditions, the study concluded. The compound effect of Tropical Storm Gordon followed by an atmospheric heatwave provided an optimal condition for Hurricane Michael to become stronger than expected."It does appear that a storm or hurricane can get stronger if the marine conditions are right," Park said. "Hurricanes Sally and Laura in the past few weeks are good examples of stronger hurricanes because of the compound effect we described in our paper. This pattern could also exacerbate other environmental problems in sensitive ecosystems such as bleaching of coral reefs, hypoxia (low oxygen in the water) and other problem that are predicted as global warming continues."