Zhong et al. (2026) Global increase in rain rate of tropical cyclones prior to landfall

Identification

• Journal: Nature Communications
• Year: 2026
• Date: 2026-01-07
• Authors: Quanjia Zhong, Jianping Gan, Shifei Tu, Ralf Toumi, Johnny C. L. Chan
• DOI: 10.1038/s41467-025-68070-z

Research Groups

• Center for Ocean Research in Hong Kong and Macau (CORE) and Department of Ocean Science, Hong Kong University of Science and Technology, Hong Kong, China
• Department of Mathematics, Hong Kong University of Science and Technology, Hong Kong, China
• South China Sea Institute of Marine Meteorology/Western Guangdong Key Laboratory of Marine Meteorological Disaster Theory and Application, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, China
• Department of Physics, Imperial College London, London, UK
• Asia-Pacific Typhoon Collaborative Research Center, Shanghai, China
• Shanghai Typhoon Institute, China Meteorological Administration, Shanghai, China
• School of Energy and Environment, City University of Hong Kong, Hong Kong, China

Short Summary

This study reveals a global increase of over 20% in tropical cyclone mean rain rate during the 60 hours prior to landfall, attributing this short-term intensification to land-sea thermal and frictional contrasts that enhance convection.

Objective

• To investigate the short-term changes in tropical cyclone (TC) rain rate prior to landfall globally and to identify the underlying physical mechanisms, particularly the roles of land-sea thermal and frictional contrasts.

Study Configuration

• Spatial Scale: Global, encompassing all ocean basins, hemispheres, latitudinal belts (5° to 35°), and TC intensity categories. TC rainfall is analyzed within a 500 km radius from the storm center, with an inner core defined as 0–200 km. Numerical simulations used a double-nested domain with an outermost size of 12000 km × 12000 km and an innermost size of 6000 km × 6000 km.
• Temporal Scale: Observational analysis covers the period from 1980 to 2020. The primary focus is on the 60 hours before TC landfall, with data analyzed at 3-hourly intervals. Numerical simulations were integrated for 240 hours, with output at 6-hourly intervals.

Methodology and Data

• Models used: Weather Research and Forecasting (WRF) model version 4.0 for idealized simulations. Key physical parameterizations included the Yonsei University boundary layer scheme, Dudhia et al. surface layer scheme, WRF single-moment six-class microphysics, Kain-Fritsch (new Eta) cumulus scheme, and RRTMG shortwave and longwave radiation schemes.
• Data sources:
  • TC best-track data: International Best Track Archive for Climate Stewardship (IBTrACS, v0400).
  • Global precipitation products: Multi-Source Weighted-Ensemble Precipitation (MSWEP), Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA 3B42).
  • Atmospheric reanalysis: European Centre for Medium-Range Weather Forecasts (ECMWF) fifth generation atmospheric reanalysis (ERA5).

Main Results

• Globally, the mean rain rate of tropical cyclones (TCs) increases by over 20% from 60 hours before landfall to the time of landfall, rising from approximately 1.8 mm h⁻¹ to 2.2 mm h⁻¹.
• This pre-landfall rain rate increase is observed consistently across both hemispheres, all six major ocean basins (with percentage changes ranging from 15% to 28%), various latitudinal belts (e.g., 44.52% in the 15°–20° belt), and all TC intensity categories.
• The majority of the observed rain rate increase originates from the inner core (0–200 km radius) of the TCs.
• TC intensification contributes only a minor portion (approximately 0.012 mm h⁻¹ per day) to the observed pre-landfall increase in rain rate.
• Numerical simulations confirm the pre-landfall rain rate increase and identify the underlying physical mechanisms: land-sea thermal contrasts enhance low-level humidity over land, while frictional differences increase convergence, upward motion, and instability on the offshore side of the TC circulation, collectively promoting increased convection and precipitation.
• Thermal contrasts between land and sea are identified as the most significant controlling factor influencing the increasing trend in rain rate and enhanced asymmetric convection.

Contributions

• Provides the first global, comprehensive observational and numerical study on the short-term (days or shorter) increase in TC rain rate prior to landfall.
• Quantifies the global mean rain rate increase (over 20%) and demonstrates its consistency across various TC characteristics (hemisphere, basin, latitude, intensity).
• Identifies and explains the physical mechanisms driving this short-term increase, specifically highlighting the crucial roles of land-sea thermal and frictional contrasts in enhancing low-level humidity, convergence, vertical velocity, and instability.
• Critically strengthens the current understanding of TC precipitation dynamics, particularly for landfalling events, and offers important insights for more effective flood management and adaptation strategies in coastal regions.

Funding

• Area of Excellence Scheme, Hong Kong Research Grants Council (AoE/P-601/23-N)
• Center for Ocean Research in Hong Kong and Macau (CORE)
• Guangdong Basic and Applied Basic Science Research Foundation (2024A1515010714)
• Natural Environment Research Council (NE/W009587/1)
• Singapore Green Finance Centre

Citation

@article{Zhong2026Global,
  author = {Zhong, Quanjia and Gan, Jianping and Tu, Shifei and Toumi, Ralf and Chan, Johnny C. L.},
  title = {Global increase in rain rate of tropical cyclones prior to landfall},
  journal = {Nature Communications},
  year = {2026},
  doi = {10.1038/s41467-025-68070-z},
  url = {https://doi.org/10.1038/s41467-025-68070-z}
}