北京城市热岛效应对气温和降水量的影响

借助非参数MannK-endall统计检验方法,对北京市20个气象站44年(1961-2004年)的逐月平均气温和降水资料进行了较为详细的分析。结果表明:①时间上,44年来北京市气温呈持续上升趋势,20世纪80年代为跃变点,跃变后增温趋势更加显著,而降水量呈下降趋势;通过分析5年滑动平均演变图发现,对气温而言,市区增温趋势明显高于郊区,市区和郊区44年来分别以0.44℃/10a和0.01℃/10a的趋势递增,降水量从总体上来说44年来城、郊差异不大,市区和郊区44年来分别以1.82mma/和1.49mma/的趋势递减。②空间上,对年平均气温而言,市区内存在一个明显的上升中心,且等值线较为密集,海淀站Kendall倾斜度高达0.776℃/10a,由于城市热岛效应的存在,1、4、7、10月在市区均存在一个闭合的暖中心,市区内增温幅度大于郊区;对降水量而言,1、4、7、10月在市区和佛爷顶一带均存在着上升中心,降水量呈现上升的趋势,这可能与城市热岛效应的影响有关。

Effect of Urban Heat Island on the Air Temperature and Precipitation in Beijing Region

The effect of urban heat island has received much attention in climate studies.On the basis of the temperature and precipitation database collected from twenty meteorological stations in Beijing from 1961 to 2004,the effect of urban heat island on temperature and precipitation was analyzed in this paper.The Mann-Kendall test was applied to annual and seasonal temperature and precipitation time series.The Mann-Kendall statistic test is a rank-based,nonparametric approach and has been widely used to estimate the significance of long-term trends in hydrometeorological time series such as water quality,streamflow,temperature,and precipitation.The results show that on the temporal aspect,(1)the annual mean temperature exhibited an increasing trend during the past 44 years.The year of 1980 is a remarkable jump point after which the increasing trend was stronger than before.On the contrary,the mean annual precipitation exhibited a decreasing trend;(2)the value of 5-year moving mean temperature in urban area was higher than that in suburban areas,especially after the year of 1980.The temperature in urban and suburban areas exhibited an increasing trend and the slope was 0.447℃/10a and 0.231℃/10a,respectively.The differences of annual mean precipitation between urban and suburban was not obvious and the slope of urban and suburban was-1.35mm/a and-1.65mm/a,respectively.In special aspect,(1)there exists an obvious rising center in urban area,among which Haidian station has showed the greatest increasing amplitude and the slope is 0.776mm/10a for the temperature.Besides that,there was a warm center in urban area in January,April,July and October,respectively;(2)there also exists a rising center for precipitation in January,April,July and October,respectively.This phenomenon maybe related to the effect of urban heat island.