Ji et al. (2026) Impacts of Small‐Scale Terrain on the Organization of an Extreme‐Rainfall‐Producing MCS Over the Southeastern Coast of China

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Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2026
• Date: 2026-09-01
• Authors: Zheng Ji, Murong Zhang, Yanluan Lin, Yipeng Huang
• DOI: 10.1029/2026jd046986

Research Groups

• Department of Atmospheric Science, Nanjing University
• Institute of Meteorology and Climate Dynamics, Karlsruhe Institute of Technology

Short Summary

This study investigates the impact of small-scale terrain on mesoscale convective systems (MCSs) over the southeastern coast of China during a record-breaking warm-sector heavy rainfall event. The results show that small-scale terrain significantly enhances coastal convergence, moisture accumulation, and upscale growth of convective cells.

Objective

• Investigate how small-scale terrain influences MCS organization and convection process in the southeastern coast of China

Study Configuration

• Spatial Scale: Regional scale (southeastern coast of China)
• Temporal Scale: Hourly to daily time scales during a 13-h period on May 7, 2018

Methodology and Data

• Models used: Terrain sensitivity numerical experiments using the Weather Research and Forecasting (WRF) model
• Data sources: Observational analyses of radar and satellite data from the China Meteorological Administration

Main Results

• Small-scale terrain reduces maximum accumulated rainfall by 73.9% without organized convective cells
• Successive small hills along the coast trap and strengthen cold pools, facilitating quasi-linear MCS formation
• Low-level and deep-layer vertical wind shear parallel to convection-initiating boundary is increased by small-scale terrain

Contributions

• This study highlights the crucial role of successive small-scale hills in coastal MCSs even with prevailing marine warm-moist flow not near-perpendicular to the coastline
• The findings provide new insights into the impact of small-scale terrain on MCS organization and convection process

Funding

• National Natural Science Foundation of China (Grant No. 41875055)
• Karlsruhe Institute of Technology's internal research funding

Citation

@article{Ji2026Impacts,
  author = {Ji, Zheng and Zhang, Murong and Lin, Yanluan and Huang, Yipeng},
  title = {Impacts of Small‐Scale Terrain on the Organization of an Extreme‐Rainfall‐Producing MCS Over the Southeastern Coast of China},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2026},
  doi = {10.1029/2026jd046986},
  url = {https://doi.org/10.1029/2026jd046986}
}