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Tropical storms pose a significant risk to coastal populations, including those throughout the Caribbean and along the Atlantic and Gulf coasts of North America. The impact of climate change on tropical storms is multifaceted, and patterns of sea surface temperature (SST) change may play a role in shaping future tropical storm risk. While the SST fingerprints associated with changes in the Atlantic Meridional Overturning Circulation (AMOC) may be uncertain, the North Atlantic Warming Hole (NAWH) and enhanced SST warming near the Gulf Stream are robust features of both past and projected future climate change. Here we use the Community Earth System Model version 2 (CESM2) to highlight the remote contributions of both of these potential SST fingerprints of AMOC decline to changes in tropical cyclone (TC) genesis potential in the Atlantic basin, and thus to uncertainty in future coastal climate risk. Both the NAWH and enhanced warming near the Gulf Stream lead to significant changes in TC genesis potential, particularly in the western North Atlantic (between Bermuda and the Bahamas), the northeastern Gulf of Mexico and the Caribbean Sea, where changes are on the order of ±10% over the full Atlantic hurricane season, with considerably stronger responses focused in the two halves of the season. Diagnosis of the Genesis Potential Index (GPI) indicates that changes in mid-tropospheric humidity and vertical wind shear are the most important factors driving these responses. The simulated changes in GPI occur in regions of considerable historical TC genesis, highlighting the need to further understand the historical and projected future patterns of SST change in the North Atlantic Ocean, including their relationship to AMOC and its potential decline.
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This content will become publicly available on December 1, 2026
Global coupled dynamics of tropical easterly waves and tropical cyclone genesis
Tropical easterly waves (TEWs) are westward-moving waves often within trade winds but occur ubiquitously in the tropics and play a significant role in the genesis of tropical cyclones (TCs). They are well-known as primary precursors of TCs in the Atlantic, yet their global relationship with TCs has been less explored. This study, for the first time, presents the global distribution of TEW activity using a combined thermodynamic and dynamic framework based on 6-hourly Outgoing Longwave Radiation and curvature vorticity. We then demonstrate that TEWs play a dominant role in approximately 22–71% of global TC genesis, with their highest impacts in the North Atlantic (71%) and Western Pacific (54%). We further identify that TEWs, in their general coupling with TC genesis dynamics, act to intensify TC convection and vorticity in all TC main development regions, albeit the vorticity enhancement is relatively weaker in the North Atlantic. To understand the cross-basin differences in this general TEW-TC relationship, we further investigated background conditions for TC genesis in each basin and found an additional dry environment constraint in the Atlantic TC genesis, yet still delineating the critical role of TEWs in TC development.
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- Award ID(s):
- 2219257
- PAR ID:
- 10639468
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- npj Climate and Atmospheric Science
- Volume:
- 8
- Issue:
- 1
- ISSN:
- 2397-3722
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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