近60年“雅安天漏”变化特征分析

针对雅安地区特殊的"天漏"气候特征及以往对其变化特征研究较少问题,利用雅安市1951~2010年降水资料,从降水量和雨日数出发,通过回归分析、小波分析等现代气候统计诊断方法,综合分析"雅安天漏"的变化特征。结果表明:在降水量上,雅安市年降水量总体呈显著减小趋势,20世纪90年代中期以后尤为明显;从季节尺度上来看,春、夏、秋三季降水量呈现明显减少趋势,但冬季与之相反;从逐月降水比重可以看出,极大值主要出现在7、8、9月;从量级上看,小雨、中雨、大雨的降水量均在减小,暴雨却在增加,但各量级降水所产生的降水量与全年总降水量的比值相对比较稳定。从雨日数上看,雅安市四季的雨日数均表现出减少趋势,各个强度量级的雨日数也均在波动减小。小波分析结果显示:年降水量和雨日数在年代际时间尺度均存在准周期振荡。

Analysis of the Characteristics Variation of "Yaan-Tianlou"over the Last 60 Years

There were few researches on the peculiar climatic characteristics of the "Tianlou" phenomenon in Yaan region in recent years.Based on the history data of Yaan city from 1951 to 2010,this paper gives a comprehensive analysis on the variation characteristics of "Yaan-Tianlou" with indicators of precipitation and rain days by using various modern diagnosis methods in meteorological statistics such as regression or wavelet analysis.The results showed that the annual precipitation trend in Yaan decreased obviously,especially since the middle of 1990s.The precipitation reduction occurred in spring,summer and autumn obviously,however increased in winter.The month-to-month precipitation showed that extremes mainly emerged in July,August,September and they changed over time.The precipitation of magnitude,moderate and heavy rain decreased,but torrential rain increased and the ratio of precipitation which produced by each rainfall grads to the whole year is relatively stable in the past 60 years.Comparing to the changes of annual rainfall precipitation days in Yaan,the rainfall days in four seasons were all on the decrease and in varying degrees.The result of wavelet analysis revealed that there exist a Quasi-Periodic oscillation in the interdecadal time scale.