Research On Precipitation Differences Of Urban And Rural Over The Climate Regions Of Central And Eastern China In Summer Based On Observational Dataset

In order to study the urban and rural differences and causes of summer precipitation with different intensity in different climatic regions of China,this paper using 30 years(1983-2012)observational data from 780 meteorological stations in China and ECMWF reanalysis data,the summer precipitation differences between urban and rural in the 5 regions,Pearl River Delta(PRD),Middle and Upper reaches of Yangtze River(MUYR),Yangtze River Delta(YRD),North China Plain(NCP),Northeast of China(NEC),of central and eastern China is studied.Analyzing the two precipitation intensities of high(24h precipitation≥100mm:HR),and low levels(0.1mm≤24h precipitation≤25mm:LR),we find that the characteristics of long-term change are different.The main conclusions as follows:1.The urbanization shows inconsistent effects on precipitation in different climate regions.The HR over urban in the PRD and YRD is more than that over the rural.On the contrary,the HR over urban in the MUYR、NCP and NEC is less than that over the rural.While the LR over urban is lower in all climate regions than over the rural.There is no significant difference in the daily variation of precipitation between urban and rural areas.The HR peak in the afternoon of city standing a little ahead of time than the rural,which shows urbanization may not completely change the HR daily variation situation,but can make the afternoon HR occurred in advance.2.Further analysis found that the correlation between precipitation and convective available potential energy(CAPE)or relative humidity in different climate regions can explain regional differences of urbanization effects on HR.HR in the PRD and YRD are greatly affected by CAPE,where the local convective instability energy is high(>600J/kg in 14:00 LT)and water vapor is abundant(water vapor content>45kg/m~2 in 14:00 LT).The urban heat island(UHI)could enhance the CAPE and promote the local atmospheric convection and increases urban HR over there.However,the HR in MUYR,NCP and NEC are greatly affected by humidity,where the local convective instability energy and water vapor are less(CAPE≤500J/kg in 14:00 LT)than that of YRD and PRD.The urban HR is mainly suppressed by urban dry islands(UDI)in MUYR,NCP and NEC.LR has a good correlation with humidity.Urban LR is mainly affected by UDI inhibition.The above research results are helpful to deeply understand the influence of summer precipitation with different intensity on urbanization,provide reference basis for future precipitation research,and provide thoughts for the government to prevent precipitation disasters such as flood and drought.