Use of high-resolution precipitation observations in quantifying the effect of urban extent on precipitation characteristics for different climate conditions over the Pearl River Delta, China

Few studies conduct a quantitative assessment between the urban extent and local precipitation characteristics. In this paper, high-resolution precipitation data and urban extent data are used to investigate the correlation between precipitation frequency, intensity and extremes and urban extent under different climate conditions over the Pearl River Delta, China. Analysis reveals that extreme precipitation amount (R = 0.45 for 1-hr maximum) and mean intensity (R = 0.56) are positively correlated with urban extent and that wet hours (R = -0.58) are negatively correlated with urban extent. The correlation coefficients between urban extent and extreme indices increase with the decrease in temporal scale of indices. The high coefficients of precipitation intensity and urban extent are mainly attributed to the precipitation under the tropical convection, and the negative coefficient of total wet hours is dominated by precipitation frequency under the Southwest monsoon. By contrast, the precipitation characteristics are less correlated with urban extent during typhoon events. Urban environments probably play a positive role in generating the short-duration heavy precipitation through enhancing deep convections induced by higher surface temperature and higher aerosol concentration.