1961—2018年四川盆地极端伏旱日数准2 a周期变化特征及其可能成因  

Quasi-biennial Period Characteristics of Extreme Summer Drought Days and Its Possible Causes in Sichuan Basin During 1961-2018

作　　者：周斌 王春学[1,2] 张顺谦 ZHOU Bin;WANG Chunxue;ZHANG Shunqian(Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072,China;Climate Center of Sichuan Province,Chengdu 610072,China)

机构地区：[1]高原与盆地暴雨旱涝灾害四川省重点实验室,四川成都610072 [2]四川省气候中心,四川成都610072

出　　处：《干旱气象》2021年第5期727-733,共7页Journal of Arid Meteorology

基　　金：四川省科技厅重点项目“四川盆地季节性干旱监测评估关键技术及机理研究”(2017JY0294);高原与盆地暴雨旱涝灾害四川省重点实验室科技发展基金“基于MCI指数的区域干旱强度评估技术研究”(SCQXKJQN2019006)共同资助。

摘　　要：利用1961—2018年四川盆地103站的气象干旱综合指数,采用多锥度奇异值分解、经验正交函数分解等方法,分析四川盆地极端伏旱日数准2 a周期的时空变化特征及其可能的形成原因。结果表明:近58 a来,四川盆地极端伏旱日数的主模态为全区一致变化型,且有明显的年际和年代际变化特征,2.3~2.5 a的年际振荡周期最为显著。准2 a周期的典型循环表现出四川盆地极端伏旱日数多寡交替的循环振荡,大值中心出现在盆地中部,与主模态空间型基本一致,但准2 a周期信号并非一直存在,20世纪60年代末到80年代初信号最强。准2 a周期典型循环的第一年,西太平洋副热带高压脊线和副热带西风急流轴线位置均偏北,四川盆地处于日本南部到中国华南西部水汽异常输送带的西部,并出现异常辐散,不利于降水产生,导致四川盆地极端伏旱日数偏多;第二年的大气环流异常情况与第一年相反,极端伏旱日数偏少。Based on MCI(meteorological drought composite index)at 103 stations of Sichuan Basin from 1961 to 2018,the temporal and spatial variation characteristics of extreme summer drought days(ESDD)in quasi-biennial period and its possible causes in Sichuan Basin were analyzed by using MTM-SVD(multi taper method and singular value decomposition)and EOF(empirical orthography function),etc.The results show that the main mode of ESDD in Sichuan Basin appeared the same variation in the whole region,the interannual and interdecadal variation characteristics were obvious,and the interannual oscillation periods with 2.3-2.5 a were the most significant in recent 58 years.The typical cycle with quasi-biennial period showed the more or less ESDD oscillated alternatively in Sichuan Basin,and the large value center appeared in the middle of the basin,which was basically consistent with the main mode of EOF.However,the quasi-biennial period signal of ESDD in Sichuan Basin did not always exist from 1961 to 2018,and the signal was the strongest from the late 1960s to the early 1980s.In the first year of typical cycle with quasi-biennial period,the locations of the western Pacific subtropical high ridge line and the subtropical westerly jet axis were to the north,Sichuan Basin located in the west of vapor abnormal transport belt from the south of Japan to the west of South China,and there was abnormal divergence,which wasn’t conducive to the formation of precipitation,further led to more ESDD.The anomaly distribution of atmospheric circulation in the second year was opposite to that in the first year,and ESDD was less.

关 键 词：四川盆地 极端伏旱日数 准2 a周期 多锥度奇异值分解 可能成因 

分 类 号：P426.616[天文地球—大气科学及气象学]