Urbanization Signal in Long-Term Precipitation Trends Estimated Based on Observed Data of National Meteorological Stations over China Mainland

Abstract The upward trend in regional precipitation intensity is evident in China for the past six decades. However, the extent to which local urbanization around the observational stations contributes to this trend remains unclear. This study examines the impact of urbanization on, and its contribution to, the trends in precipitation indices as estimated based on daily precipitation data of national stations across China mainland during 1960–2018. Our analysis reveals that the urbanization signal is detectable in the estimated trend of regional mean precipitation indices. Specially, the urbanization effect accounts for at least 10% of the long-term increase in annual total precipitation, with a more substantial contribution to the increase (decrease) in precipitation intensity (frequency). The pronounced urbanization effect is observed during the warm season, which accounts for at least 16% of the increasing summer intensity. Spatially, the precipitation increase is significantly affected by urbanization over eastern China, and urbanization also intensifies the upward trend of the three precipitation indices over the southeastern portion, though it decreases the observed frequency overall in China mainland. Urbanization induces an asymmetric change from light toward heavy precipitation, particularly in southeastern China, while it causes the precipitation intensities in most quantile ranks to increase. Thus, the spatial–temporal pattern of observed precipitation frequency change contains a significant urbanization signal. These findings indicate that the observed precipitation change in China mainland, characterized by increased amount and intensity but decreased frequency, could be explained at least partially by urbanization around the meteorological stations. It implies that the large-scale change in precipitation observed based on station data in the country may not solely be a regional response to anthropogenic global warming.