Observed Link Between Spatial Pattern of Heavy Precipitation in Urban Cluster and Environmental Factors in the Greater Bay Area

                  Observed Link Between Spatial Pattern of Heavy Precipitation in Urban Cluster and Environmental Factors in the Greater Bay Area

Zheyu He^a, Jiachuan Yang^{a, *}

^a Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China

Global urbanization has rapidly increased over the past few decades, leading to the emergence of urban clusters comprising multiple adjacent cities and their surrounding areas. The Greater Bay Area (GBA) is one of the most urbanized clusters in China. Research indicates that urbanization processes—such as the urban heat island (UHI), building barrier effect, and aerosol emissions—significantly alter precipitation patterns in both urban and surrounding regions. However, most existing studies have primarily focused on the precipitation modifications in individual cities due to singular factors, often emphasizing the enhancement of precipitation occurring downwind of urban centers.

This study focuses on the GBA urban cluster, utilizing observational and reanalysis data to examine the spatial patterns of regional heavy precipitation events during the warm season (May-Sep) from 2010 to 2017 under varying conditions of regional UHI and ambient wind speed. Quantitative indicators, including horizontal and vertical precipitation profiles and regional precipitation anomaly ratios, were employed to analyze and compare the spatial distribution of precipitation between the central urban area and surrounding suburbs, as well as across different directions and distances from the urban center. This research investigates the potential link between extreme precipitation events in urban cluster and UHI under varying ambient wind conditions, thereby addressing gaps in the current literature regarding how urban clusters influence precipitation distribution in complex environments.