滇中城市降水特征及其成因分析

基于滇中城市群4个主要城市(昆明、曲靖、玉溪和楚雄)近50年的降水资料, 利用统计分析、小波分析、累计距平和灰色关联度分析等方法, 分析滇中城市降水量的年、季、月变化特征以及影响降水量的各种因子。结果表明, 滇中城市近50年平均降水量为928.1 mm, 整体上呈下降趋势, 并在2009年发生突变; 降水量有干、湿季之分, 雨季(5—10月)降水多, 干季(11月至次年4月)降水少, 最大降水量出现在7月(184.0mm), 最小降水量出现在12月(13.8 mm)。通过小波分析, 发现年降水量呈现22年左右的主周期变化; 夏季降水量呈现以19天为主周期的增减变化, 降水多, 变幅小; 冬季降水量呈现以20天为主周期的增减变化, 降水少, 变幅大。通过灰色关联度分析, 发现自然因子中对降水影响较大的是气温和相对湿度, 人文因子中对降水影响最大的是人口和城市面积, 并且, 自然因子的作用大于人文因子。

Analysis of Precipitation Characteristics and ItsCauses in Central Yunnan City

Basing on the nearly 50-year precipitation data of 4 major city (Kunming, Qujing, Yuxi, Chuxiong) inurban agglomeration of central Yunnan, this paper analyzes the variation of precipitation in annual, seasonal, andmonthly time scale by using methods including the statistical analysis, the wavelet analysis, accumulative levelingmethod, and the grey relational analysis. The result shows that the average precipitation in past 50 years is 928.1mm. The trend of precipitation is declining, and a mutation appears in 2009. Besides, precipitation has a dry andwet season in these region, and the wet season is between May and October but the dry season is betweenNovember and April of next year, There are more precipitation in the rainy season and less precipitation in dryseason. The maximum of precipitation (184.0 mm) appears in July, but the minimum of precipitation (13.8 mm)appears in December. According to the wavelet analysis, the change of annual precipitation is about 22 years, thesummer precipitation has a 19-day increase-decrease cycle with more precipitation and smaller variation, and thewinter precipitation has a 20-day increase-decrease cycle with less precipitation and larger variation. The greyrelational analysis show that the temperature and the specific humidity are dominant natural factors, and thepopulation and the city size are dominant human factors. Besides, the natural factors play greater role than theartificial factors.