Work

Pre-Storm Upper-Ocean Warm-Layer Conditions and Vertical Wind Shear Associated with Rapid Intensification in the Western North Pacific

Year: 2026

Type: article

Abstract: Rapid intensification (RI) in the western North Pacific (WNP) occurs in broadly warm sea surface temperature (SST) conditions, making pre-storm ocean structure potentially informative. Using 1993–2024 best tracks, SST, the ERA5 atmospheric reanalysis, and the GLORYS12V1 global ocean reanalysis, we evaluate upper-ocean heat content above 26 °C (OHC26), 26 °C isotherm depth (D26), and atmospheric environmental conditions in relation to 24 h intensity increases of 15 and 20 m s−1 (RI15 and RI20). At fixed locations 24 h before arrival, RI15 environments had 33.91 kJ cm−2 higher OHC26 and 26.57 m deeper D26 than all non-RI records. Restricting controls to other intensifying records reduced, but did not remove, these contrasts: +18.28 kJ cm−2 and +15.37 m for RI15. Storm-grouped validation showed persistent gains from pre-storm OHC26 across pre- and post-2005 periods. RI frequencies were highest where weak vertical wind shear coincided with substantial warm-layer support; however, formal cluster-robust ocean–shear interaction terms were not statistically significant. The findings identify robust pre-existing warm-layer associations with RI while limiting inference about nonlinear environmental gating, ocean-response causality, or operational forecast skill.

Source: Atmosphere

DOI: 10.3390/atmos17111095

Authors: Wanwan Wei, Jian Li

Institution: Nanjing University of Information Science and Technology

Language: English

Topic: Tropical and Extratropical Cyclones Research

Subfield: Atmospheric Science

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDG: Climate action

Open Access status: gold

Estimated APC paid: $2,896