Analysis of the driving factors of precipitation change during the development of the Jing-Jin-Ji urban agglomeration

Abstract

Urbanization has an important impact on local precipitation changes. Previous studies of urban precipitation have largely considered single precipitation events, with few long-term statistical studies based on multiple samples. Therefore, based on WRF model simulations, this study extracted the latent heat flux, sensible heat flux, net radiation, friction velocity, albedo, and precipitation of 156 urban units in Beijing-Tianjin-Hebei (Jing-Jin-Ji) urban agglomeration for the summers of 2001–2019, and identified the main factors driving long-term urban precipitation changes based on multiple samples. There were three key results. 1) The factors that had the greatest impact on urban precipitation changes in Jing-Jin-Ji were the sensible heat flux, latent heat flux, and friction velocity. The latent heat flux was the leading factor driving precipitation changes during the urbanization of Jing-Jin-Ji. 2) In the different stages of urbanization, there were different factors affecting urban precipitation changes. In highly urbanized cities, the sensible heat flux had the greatest impact on precipitation changes, followed by the friction velocity. For medium-sized cities, the friction velocity was the most important variable. For small cities, the latent heat flux was the most important factor. 3) The friction velocity was the leading factor in precipitation change at the 0.95 quantile in Jing-Jin-Ji, and was therefore the most important factor driving changes in urban extreme precipitation. The results provide a theoretical basis for the formulation of climate policies, and disaster prevention and mitigation in Jing-Jin-Ji. They will also assist in promoting the construction of an ecological civilization and building safe and livable cities.