2026-09-04 パシフィック・ノースウェスト国立研究所（PNNL）
Hurricane Erin, a large Atlantic storm, on August 20, 2025. Although the storm didn’t make U.S. landfall, significant flooding occurred along the East Coast, especially near North Carolina, due to its size.(Image: NOAA)
＜関連情報＞
- https://www.pnnl.gov/publications/western-north-atlantic-hurricanes-show-expanding-wind-fields
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025EF007162
北大西洋西部における最近の熱帯低気圧の外径拡大 Recent Tropical Cyclone Outer Size Increases in the Western North Atlantic
Karthik Balaguru, Chuan-Chieh Chang, L. Ruby Leung, Paul A. Ullrich, Yushan Han, Julian R. Rice, Samson Hagos, Daniel Chavas, Sourav Taraphdar, Bryce Harrop, Ning Sun, David R. Judi
Earth’s Future Published: 10 February 2026
DOI:https://doi.org/10.1029/2025EF007162
Abstract
The outer size of a tropical cyclone (TC) plays a pivotal role in its impact through a modulation of wind duration, rainfall extent and storm surge. While global and basin scale trends in TC size have been examined previously, whether there have been regional changes over time remains unclear. Here, using a suite of observations and reanalyses, we detect an increasing TC outer size over the western North Atlantic during 1979–2022. Over the western subtropical North Atlantic where the largest changes are found, the area-averaged increase in the radius of 17 ms−1 winds is about 7.5% over this period. Analysis of the large-scale environment reveals that the air-sea thermodynamic state has become more favorable for storm intensification, and thereby expansion, over that region. Further, numerical model simulations link changes in the environment with those in storm size, and suggest a combination of natural variability and external forcing in driving them.
