基于CI指数的四川盆地春季干旱时空演变分析

基于1961~2016年四川盆地101个地面观测站逐日降水资料，计算综合气象干旱指数（CI），应用气候倾向率、经验正交函数分解和小波分析等统计诊断方法，分析四川盆地春旱强度和天数的时空变化特征。结果表明:四川盆地西南部春旱强度高于其它地区，而盆地中部春旱天数较多，尤其是内江以北地区更为突出；近56a四川盆地春旱强度和天数的长期变化呈显著负相关，春旱天数呈减少趋势，春旱强度呈增加趋势；四川盆地春旱强度和天数的EOF第一模态方差贡献率分别为42.99%和44.24%，均反映出空间变化的整体一致性；四川盆地春旱强度和天数均存在1~4a、5~12a及14~28a的振荡周期。 

Analysis on the Characteristics of Spring Drought in Sichuan Basin Based on CI Index

Based on the daily precipitation data of 101 weather stations in Sichuan Basin from 1961 to 2016 integrated meteorological drought index (CI) , and using climate tendency rate, empirical orthogonal function (EOF) and wavelet decomposition method analysis of climatic statistical diagnosis methods, the spatial and temporal variations of intensity of spring drought and the spring drought days are analyzed. The results show that the spatial distribution of the intensity of spring drought in southwest of Sichuan Basin is higher than that in other areas, and the days of spring drought in central part of Sichuan Basin are more, especially in the north of Neijiang. In recent 56 years, there was a significant negative correlation between the number of days of spring drought and the long-term variation trend of the intensity of spring drought. The number of days of spring drought generally decreased, while the intensity of spring drought generally increased. Regardless of the intensity of spring drought or the number of days of spring drought, the first characteristic vector of spring drought presented the same positive and negative changes in the whole Sichuan Basin, which was the most important spatial mode, and the corresponding variance contribution rate were 42.99% and 44.24%, respectively. The intensity and the number of days of spring drought have periodic changes of 1~4 years, 5~12 years and 14~28 years.