Liu et al. (2026) Increasing synchronized hourly heavy rainfall over South China reflects enhanced multi-cluster and multi-regional coactivity

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2026
• Date: 2026-08-07
• Authors: Haisheng Liu, Xiaogang Huang, Jianfang Fei, Xiaoping Cheng, Xiadong An, Xiangcheng Li, Shunzhi He
• DOI: 10.1038/s41612-026-01496-4

Research Groups

• College of Meteorology and Oceanography, National University of Defense Technology, Changsha, China
• Yunnan Key Laboratory of Meteorological Disasters and Climate Resources in the Greater Mekong Subregion, Yunnan University, Kunming, China
• Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science &Technology, Nanjing, China
• College of Marine Science and Technology, Hainan Tropical Ocean University, Sanya, China

Short Summary

This study examines the increasing synchronized hourly heavy rainfall over South China during the 1981-2020 pre-summer rainy season. The results show a significant increase in synchronized heavy-rain hours, equivalent to about +16.7% of the 40-year mean per decade.

Objective

• Investigate changes in hourly precipitation synchrony over South China
• Determine whether the increase in synchrony is due to local frequency changes or true spatial organization

Study Configuration

• Spatial Scale: Regional scale, covering South China and surrounding areas
• Temporal Scale: 40-year period (1981-2020) during the pre-summer rainy season

Methodology and Data

• Models used: ERA5 environmental diagnostics
• Data sources: Hourly rain-gauge observations over South China

Main Results

• Synchronized hourly heavy rainfall has increased over South China, with a significant increase in synchronized heavy-rain hours of 0.24 percentage points decade-1.
• The increase is dominated by multi-cluster and multi-regional coactivity rather than single-system expansion.
• The most consistent environmental signal is a higher frequency of event-like circulation windows.

Contributions

• This study provides new insights into the spatial connectedness dimension of short-duration extremes, highlighting its relevance for compound flood-hazard assessment in humid monsoon regions.
• The results show that synchronized heavy rainfall is becoming more frequent and important contributors to seasonal rainfall over South China.

Funding

• This research was supported by the National Natural Science Foundation of China (Grant No. 41675045)

Citation

@article{Liu2026Increasing,
  author = {Liu, Haisheng and Huang, Xiaogang and Fei, Jianfang and Cheng, Xiaoping and An, Xiadong and Li, Xiangcheng and He, Shunzhi},
  title = {Increasing synchronized hourly heavy rainfall over South China reflects enhanced multi-cluster and multi-regional coactivity},
  journal = {npj Climate and Atmospheric Science},
  year = {2026},
  doi = {10.1038/s41612-026-01496-4},
  url = {https://doi.org/10.1038/s41612-026-01496-4}
}