城市化建设对降水特征的影响

城市化建设导致城区下垫面热力学、动力学特性以及大气成分发生显著变化,进而影响降水过程。论文采用广州市1980、1990、2000和2010年土地遥感数据反演城市化建设进程,并利用1984—2015年汛期（4—9月）逐时降水资料分析城市化建设对降水特征的影响。研究结果表明：1）2000年后广州市城市化建设明显加快,城镇土地以20.3 km²/a的速度扩张,进入城市化快速期;2）对比城市化缓慢期,城市化快速期城区短历时降水发生时段变化显著,短历时1~3 h降水午后发生频率明显增加4.1%,短历时4~6 h降水凌晨发生频率明显增加5.2%;3）城市化快速期城区短历时降水强度增强,短历时1~3 h、4~6 h降水平均强度分别提高7.4%和10.9%,极端小时所占比例分别增加2.4%和4.4%;4）城市化快速期城区短历时降水雨型变化明显,短历时4~6 h降水事件中单峰型、前期与中期集中型降水年均次数分别增加29.1%和41.9%。

Effects of Urbanization on Precipitation Characteristics

With the process of urbanization, the changes of surface types and atmospheric layer have affected precipitation in urban areas. Based on the remote sensing data of the year 1980, 1990, 2000 and 2010, the urbanization process of Guangzhou was analyzed. The possible effects of urbanization on precipitation were further investigated using the hourly precipitation data in flood seasons of 1984-2015. Results show that: 1) The urban land has expanded at the rate of 20.3 km²/a since 2000, which suggests Guangzhou is in the period of rapid urbanization. 2) Compare with that in slow urban expanding period, the diurnal variation of short term precipitation in rapidly urban expanding period changed greatly, that the frequency of short-term rainfall events with 1-3 h duration in the afternoon increased by 4.1% and the frequency of rainfall events with 4-6 h duration in night increase by 5.2%. 3) In rapidly urban expanding period, the precipitation intensity in the city strengthened that the average precipitation intensities of rainfall events with 1-3 h and 4-6 h duration improved 7.4% and 10.9% respectively and the percentages of extreme hourly precipitation improved 2.4% and 4.4% respectively. 4) The rainfall pattern of precipitation events with 4-6 h duration evidently changed in rapidly expanding period that the annual mean frequencies of rainfalls with unimodal peak and rainfalls with early or middle peaks increase by 29.1% and 41.9%, respectively.