Typhoon Haiyan shortly before maximum intensity while approaching the Philippines on November 7, 2013
Burgeoning ocean hotspots feed big storms
Lin's ongoing recent work, the topic of her discussion at the upcoming session in the American Geophysical Union's 2025 Annual Meeting, reveals that most of these Category '6' tropical cyclones occur in hot spots. The largest hot spot for these massive storms is in the Western Pacific east of the Philippines and Borneo, while another hot spot lies in the North Atlantic around and to the east of Cuba, Hispaniola and Florida.
Their work also reveals that these hot spots are growing in size-the North Atlantic hot spot has expanded eastwards past the northern coast of South America and westwards into much of the Gulf, while the Western Pacific has grown as well.
The conditions that drive Category '6' storms are driven by warmer subsurface water as well as warm surface water. In other regions, big storms often churn up the ocean. As cool water is drawn into the surface, it can cool the storm itself, reducing its intensity. But since warm water is so deep in these hot spot regions, the cyclones don't have a chance to cool as much. Just the same, Lin cautions that not every storm that arises in these hot spots will become a Category '6' tropical cyclone-the atmospheric conditions have to be right as well. "The hot spots are a necessary but not sufficient condition," she said.
Analysis of the factors driving this expansion of deeper warm water in these hot spots has revealed that global warming and natural variability in temperature both play a role. But overall, the team estimates that human-caused climate change is responsible for about 60-70% of the increased size in these hot spots-and consequently, of Category '6' tropical cyclones.
Lin said that recognition of Category '6' tropical cyclones by weather agencies could help cities plan more appropriately for the impact of coming storms-especially in hot spot areas where they are becoming more common. "We really think there is a need just to provide the public with more important information," Lin said.
Contributed by Joshua Rapp Learn
Abstract information:
A31A-06 Category '6' Tropical Cyclone Hot Spots in the Warming Climate
Wednesday, 17 December, 9:34 - 9:45 Central Time
Room 278-279 (NOLA Convention Center)
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