城市热岛效应对西宁地区夏季降水的影响

Impact of Urban Heat Island Effect on Summer Precipitation in Xining

利用1986-2015年西宁城区、大通和湟中三个站气温和降水资料,通过线性回归、距平分析、Mann-Kendall检验等方法分析了夏季城市热岛效应对西宁地区夏季降水的影响。研究表明,1986-2015年西宁城区的夏季城市热岛强度呈减弱趋势,最高气温对其贡献最大。近30年西宁地区的夏季气温呈显著上升趋势,西宁城区、大通和湟中平均气温的升温率分别达0.7、1.0℃/10 a和0.5℃/10 a,西宁城区夏季气温在1997年出现突变,湟中在1994年出现突变,大通未发生突变。近30年西宁城区的夏季降水量和降水日数分别以4.5 mm/10 a和1.2 d/10 a的趋势增加;大通的夏季降水量在增加,降水日数在减少;湟中的夏季降水量和降水日数均在减少。三个站的夏季降水量突变主要出现在20世纪90年代,西宁城区还在2000年发生突变。城区夏季最高气温热岛强度和最高气温与夏季降水量和降水日数之间有较好的相关性,郊区也是夏季最高气温与降水量的相关性最好。城市热岛效应对降水的影响主要是由于盛行风向和河谷地形的作用。

In this study,timeseries data of temperature and precipitationfrom 1986 to 2015 of 3 meteorological stations were collected and means of linear regression,anomaly analysis,Mann-Kendall test were used to reveal the influence of urban heat island effect on summer precipitation in Xining.The results showed that the intensity of summer urban heat island in Xining City exhibited downward trend during 1986-2015,and the summer maximum temperature contributed the most to the summer urban heat island.The summer temperature in Xining area showed a significant rising trend in the 30 years.The average temperature rise rates of Xining City,Datong and Huangzhong were 0.7℃/10 a,1.0℃/10 a and 0.5℃/10 a,respectively.The summer temperature in Xining city had a mutation in 1997,Huangzhong in 1994,Datong had no mutation.In the past 30 years,the summer precipitation and the number of precipitation days in Xining city increased by 4.5 mm/10 a and 1.2 d/10 a,respectively;the summer precipitation in Datong increased and the number of precipitation days decreased;the summer precipitation and the number of precipitation days in Huangzhong decreased.The abrupt changes of summer precipitation in three stations mainly occurred in 1990s,and in Xining City in 2000.There was a good correlation between the summer maximum temperature heat island intensity and the maximum temperature in urban area and the summer precipitation and the number of precipitation days.The effect of urban heat island on precipitation is mainly due to prevailing wind direction and valley topography.