Dr Yali Luo is a professor at the School of Atmospheric Sciences, Nanjing University of Information Science and Technology (NUIST), and director of Institute of Weather Research. Her research centers on understanding the dynamics and impacts of extreme weather and climate events, with a particular focus on convective storms, extreme precipitation, and heatwaves. She specializes in analyzing cloud and convective processes across scales, employing high-resolution observational analysis and process-oriented modeling to uncover the mechanisms that govern their behavior and evolution. By integrating satellite data, ground-based observations, and advanced numerical simulations, her work aims to improve the prediction and projection of extreme events in a warming climate as well as support enhanced resilience planning and risk mitigation strategies.
Quasi-linear Mesoscale Convective Systems and Associated Extreme Precipitation over Coastal South China
This talk focuses on quasi-linear mesoscale convective systems (MCSs) associated with extreme precipitation over South China during the pre-summer rainy season, with particular emphasis on those composed of multiple parallel rainbands (MPRB). Based on high-resolution gridded radar network data and T-mode obliquely rotated principal component analysis, we examine the general features and synoptic-scale environments of 98 quasi-linear MCSs during May 1-June 15, 2013-2017 and identify five organizational modes at their mature stages. Among them, MPRB-MCSs occur mainly near the coastline, with the longest lifespan (about 6.6 h) and slowest propagation speed (about 14.0 km h-1), leading to the most extreme rainfall events with maxima exceeding 300 mm per event. This presentation then summarizes observational analyses of three extreme-rainfall cases, focusing on the formation of the coexisting “cell training and rainband training” structure and key influencing factors, including coastal mountains, weak cold pools, and warm, moist onshore flows with near-zero convective inhibition from the northern South China Sea. A rapid splitting and reestablishment (RSRE) process that contributes to rainband training in one case is also highlighted. Convection-permitting WRF simulations further reveal that an accurate representation of the diurnal boundary layer thermal structure is essential for predicting such warm-sector nocturnal extreme rainfall along the South China coast in the pre-summer rainy season, complementing the previously emphasized nocturnally enhanced marine boundary layer flow. Synthesized from our published work, these findings clarify the key properties of extreme-rain-producing MCSs and their favorable environmental conditions and formation processes, providing valuable guidance for improving quantitative precipitation forecasting along the South China coast.