基于降水数据的云南省近61年旱涝特性研究

选择标准化降水指数(SPI)刻画旱涝特征，基于云南省1954—2014年间32个气象站点逐月降水量资料，采用经验正交函数(EOF)方法、径向基函数(RBF)空间插值法、小波分析法，分析了近61年来云南省SPI序列、旱涝情态的时间特征和空间格局。结果表明:近61年来，云南省整体呈现干旱趋势(SPI变率为-0.009 1)，SPI序列在2000年之后变化更加剧烈、速率加快。旱涝等级时间序列中，偏涝至偏旱年份占88.52%，大旱占4.92%，重旱和大涝均占3.28%，且自2003年以后，发生干旱的次数和强度明显增加。旱灾易发区主要分布于2个片区:景洪-思茅-元江站片区，以及沾益站东北地区；洪涝易发区主要分布于3个片区:临沧-大理-华坪沿线的西部片区，昭通站北部区域，及云南省东南部片区。干旱与洪涝事件发生的频率具有较好的对应性，但干旱事件发生的频率要略高于洪涝事件。EOF分析的第一个模态表明云南省整体呈现一致性的变涝或变旱特征，可能受到大尺度气候特征影响，第二模态可能受到地形因素的控制，第三模态可能与季风、大气环流等多种因素的影响有关；相应的时间系数也印证了云南省整体具有干旱趋势。SPI序列存在准2 a、准6 a、准8 a、准18 a、准28 a的周期性特征，且以准28 a为主周期。 

A STUDY ON CHARACTERISTICS OF DROUGHT AND FLOOD BASED ON PRECIPITATION DATAIN YUNNAN PROVINCE OVER THE PAST 61 YEARS

Analyzing the characteristics of spatio-temporal variability of droughts and floods is very important to reducing losses and costs. Based on the monthly rainfall data from 1954 to 2014 collected from 32 meteorological sites in Yunnan province, the spatio-temporal variability and periodicity of drought and flood were analyzed using SPI, EOF, RBF spatial interpolation, and wavelet analysis. The results show that there is a tendency of drying in Yunnan province during the past 61years (the slope of SPI is -0.0091/year), and the SPI clearly indicates a great fluctuation and a high frequency after 2000. General flood years, normal years and general drought years account for 88.52% of the total in the 61 years, and great drought years, extreme drought years and great flood years account for 4.92%, 3.28%, and 3.28%, respectively. Since 2003, furthermore, drought eventshave beenmuch more frequent and serious. Jinghong-Simao-Yuanjiangand the area northeast of the Zhanyisiteare the two regions where droughts occur more frequently than the other regions in Yunnan province. And three regions, namely, the west of Lincang-Dali-Huaping line, the area north ofthe Zhaotong site, and the southeast of Yunnan province are where floods appear frequently. The frequency of drought and flood events have good correspondence, but the frequency of drought events is slightly higher than that of flood events. The first mode of EOF analysis reveals that Yunnan province shows flood or droughtconsistency, possibly affected by large-scale climate characteristics. The second mode may be controlled by topographical factors, and the third mode may be caused by multiple factors, such as monsoon and general atmospheric circulation. The time coefficients of the first three modes also confirm the trend of drought in Yunnan province. The periodic oscillation of SPI series is concentrated in quasi-2, 6-, 8-, 18- and 28-years, with the period of quasi-28 years being the dominating period.