1970-2020年秦岭南北降水季节性时空变化及其影响因素  

Spatio-temporal variation of precipitation seasonality and impact factors in south and north of the Qinling Mountains in 1970-2020

作　　者：李双双 胡佳岚 延军平 Li Shuangshuang;Hu Jialan;Yan Junping(School of Geography and Tourism,Shaanxi Normal University,Xi’an 710119,Shaanxi,China)

机构地区：[1]陕西师范大学地理科学与旅游学院,陕西西安710119

出　　处：《地理科学》2025年第1期227-238,共12页Scientia Geographica Sinica

基　　金：国家自然科学基金项目(41701592);陕西省自然科学基础研究计划项目(2023-JC-QN-0321)资助。

摘　　要：基于1970-2020年逐日降水数据,辅以经验正交分解法、趋势分析等方法,对秦岭南北降水季节性指数(PSI)时空变化特征进行分析,识别降水季节性空间主导模态,探讨降水季节性空间异常与全区海温的遥相关关系。结果表明:(1) 1970-2020年,秦岭南北PSI线性变化趋势并不显著,以3.2 a的年际波动周期为主。1997年后,较长干季逐渐成为区域降水季节性的常态;(2)在空间上,秦岭南北有61.3%的区域降水季节性为单一空间主导型,组合类型相对较少。其中,湿季偏长和干湿均衡是单一形态的主导类型;“干湿均衡-干季偏长”是组合形态的主导类型;(3)前冬、春季北大西洋涛动处于负相位,赤道中东太平洋由厄尔尼诺转拉尼娜时,秦岭南北PSI异常偏高,全区发生极端干旱风险较高。Based on daily precipitation data from 1970 to 2020,we analyzed the spatio-tempor-al variation of precipitation seasonality index(PSI)in south and north Qinling Mountains.Then,the empirical orthogonal function(EOF)analysis is performed to identify the leading spatial patterns of PSI in the study region.More specially,we discussed the relationship between the leading spatial pat-terns of PSI and sea surface temperature anomaly(SSTA).The results show that:1)The change of PSI in south and north of the Qinling Mountains was mainly synchronous variation over the past 51 years.Before 1997,it could be observed one peak(dry)periods(1975-1986)and two valley(wet)periods(1970-1975 and 1987-1996)of PSI variation.After 1997,the precipitation showed markedly seasonality with a long drier season in 1997-2015,which indicated the dry climate is be-coming the normal condition for China’s south-north transitional geographical zone.2)Spatially,the single type of precipitation seasonality is clearly seen over most regions(61.3%of the study area)and the combined type of precipitation seasonality(32.7%of the study area)does not pre-vail.In detail,for the single type,the eastern part of Hanjiang River Basin and western part of Daba Mountains(28.3%of the study area)are mainly controlled by a longer wet season.Moreover,precipitation seasonality with the dry-wet balance accounted for 22.9%of the study area,which located in the west of Jialing River Basin,Hanzhong Basin,Ankang Basin and the middle of Guanzhong Plain.3)This study investigates the first leading spatial patterns of the in-terannual variability of PSI in the south and north Qinling Mountains.The positive phase of the first leading mode(EOF1)showed characterized by positive PSI anomalies for the whole re-gion.The positive phase of EOF1 was significantly associated with the negative phase of North Atlantic Oscillation(NAO)from pre-winter to spring,as well as the transition from El Niño in pre-winter to La Nina in summer.

关 键 词：气候变化 降水季节性指数 厄尔尼诺 北大西洋涛动 秦岭南北 

分 类 号：P426.6[天文地球—大气科学及气象学]