Contribution of climate change and urbanization to the variation of extreme precipitation in the urban agglomerations over the Loess Plateau

With global warming and rapid urbanization, urban agglomerations (UAs) over the Loess Plateau (LP) are suffering from various urban disasters. Urbanization has aggravated the decreasing trends of extreme precipitation in Taiyuan and Xi'an UAs and enhanced the increasing trends of extreme precipitation in Luoyang, Hohhot and Xining UAs during 1979-2018. Meanwhile, the number of light rain days decreases in almost all the cities, indicating the sensitivity of light rain days to urbanization. Climate change is a primary contributor to the change of urban precipitation during 1979-2000 in this region. But, the contribution of urbanization has been increasing gradually since 2000, and it further amplifies the influence of climate change. In terms of physical mechanisms, rapidly increasing surface temperatures and aerosol particles are closely related to urban precipitation. Our findings provide a systematic understanding of the urbanization effects on extreme precipitation over the LP, playing an important role in the mitigation of future urban disasters.