Asymmetrical Shift Toward Less Light and More Heavy Precipitation in an Urban Agglomeration of East China: Intensification by Urbanization.

Under global warming, projected changes in precipitation have shown an asymmetrical shift from light to heavy precipitation over China. However, the role of urbanization in this shift remains unknown. Here, we show that increases in total rainy‐season (May‐September) precipitation over the Yangtze River Delta (YRD) urban agglomeration of East China are characterized by decreasing light precipitation and increasing heavy precipitation during 1961–2019. This asymmetrical shift toward heavier precipitation is even more prominent in urban than rural areas. Areas with faster urban expansion rates exhibit stronger negative (positive) trends in light (heavy) precipitation. Urbanization contributes to 44.4% (26.4%) of the decreasing (increasing) light (heavy) precipitation in the urban areas of the YRD. We suggest that urban managers should consider potential adverse impacts of this asymmetrical shift, which may favor increases in both the frequency of heatwaves and waterlogging. Plain Language Summary: China has experienced rapid urbanization in recent decades, alongside decreases in light precipitation and increases in heavy precipitation. This shift in precipitation patterns is also observed in the Yangtze River Delta (YRD), a typical densely populated region of China. Over the period 1961–2019, urban areas of the YRD have witnessed intensifying precipitation characterized by sharper decreases in light precipitation as well as sharper increases in heavy precipitation than rural areas. We estimate that 44.4% of the decrease in light precipitation and 26.4% of the increase in heavy precipitation in urbanized areas can be attributed to urbanization. Key Points: Changes in rainy‐season precipitation over the YRD show an asymmetrical shift toward less light and more heavy precipitationThis asymmetrical shift has been amplified by rapid urban expansion in recent decadesUrbanization contributes to 44.4% of the decrease in light precipitation and 26.4% of the increase in heavy precipitation [ABSTRACT FROM AUTHOR]