1961—2010年北京地区降水变化特征

Precipitation Changes over the Beijing Area during 1961-2010

采用15个常规气象站1961—2010年逐日降水数据资料,分析了北京地区降水量、降水日数和降水强度的变化趋势,包括年和各季节的总降水量和降水日数,不同降水级别降水量、降水日数和降水强度变化趋势的时空特征。结果表明:在近50 a内,北京地区平均年降水量和年降水日数、年降水强度均呈下降趋势;各季节中,夏季的降水量呈明显下降趋势,春季降水日数略有增加,夏季略有减少;降水强度在春季增大和夏季减小趋势明显;小雨雨量变化不明显,中雨雨量呈增加趋势,大雨和暴雨雨量呈明显减少趋势;小雨降雨日数略呈减小趋势,中雨降水日数呈显著增加趋势,大雨和暴雨降水日数呈较明显降低趋势;小雨降水强度略呈上升趋势,而大雨和暴雨的降水强度呈明显的降低趋势。

The changes in precipitation were studied on the basis of daily precipitation observations from 20 meteorological stations between 1961 and 2000 over the Beijing area. During the past 50 years, there was an obvious decreasing trend in the regionally averaged annual precipitation, especially in summer. The regionally averaged amount of annual precipitation days showed slightly negative trends. There were large differences in linear trends of the precipitation among different grades. The amount of light rain （0.1-10 mm） and moderate rain （ 10-25 mm） slowly increased, while the amount of heavy rain （≥25 mm） showed an obvious decrease. For the amount of days of different grade precipitation, the light rain experienced a non-significant decrease, moderate rain a significant increase, and heavy rain experienced a non-significant declining trend. For the intensity of different grade precipitation , the light rain and moderate rain had little change, but the heavy rain experienced highly significant decreasing trend.