夏季南亚高压年代际变化及其对长江中下游降水的影响  

Interdecadal Variation of the South Asian High in Summer and Its Impact on Precipitation over the Middle and Lower Reaches of Yangtze River

作　　者：张莹 王锦杰 曾刚[2] 周航 庞礴 ZHANG Ying;WANG Jin-jie;ZENG Gang;ZHOU Hang;PANG Bo(Suqian Meteorological Bureau,Suqian 223800, China;Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science & Technology, Nanjing 210044, China)

机构地区：[1]宿迁市气象局,江苏宿迁223800 [2]南京信息工程大学气象灾害教育部重点实验室,江苏南京210044

出　　处：《长江流域资源与环境》2019年第7期1663-1674,共12页Resources and Environment in the Yangtze Basin

基　　金：宿迁市科技支撑计划项目(S201607);江苏省青年气象科研基金项目(Q201603);国家自然科学基金项目(41430528);国家重点研发计划(2017YFA0603800)

摘　　要：夏季南亚高压对我国长江中下游旱涝分布有重要影响,为深入认识长江中下游夏季降水年代际演变规律和机理,提高其短期气候预测水平,利用1960~2015年NCEP/NCAR再分析资料和地面气象站降水资料,分析夏季南亚高压年代际变化及其对长江中下游降水的影响。结果表明:夏季南亚高压强度、面积、南界、东伸脊点、西伸脊点和脊线均存在显著的年代际变化,长江中下游夏季降水也有明显年代际转折,南亚高压脊线与长江中下游夏季降水相关最好,呈显著负相关。夏季南亚高压脊线年代际偏南期,南亚高压偏大偏强,长江中下游高层气流强,且形成发散;副高增强西伸,印度有稳定低压存在,长江中下游处于副高西北侧和西风槽前,盛行西南风,与北方来的偏西气流汇合;低层风场有明显切变和辐合,从孟湾、南海输送来的水汽在长江中下游辐合上升,导致降水偏多。1990s初至2000s初,夏季南亚高压年代际减弱西撤,副高减弱东撤,但由于两个高压减弱程度较小,长江中下游夏季降水仍偏多。The South Asian high(SAH) in summer has an important effect on the distributions of drought and flood in the Middle and Lower Reaches of Yangtze River. In order to understand the interdecadal evolution of summer precipitation over the Middle and Lower Reaches of Yangtze River and improve the short-term climate prediction level, interdecadal variation of the SAH in summer and its impact on precipitation in this region was analyzed by using the NCEP/NCAR reanalysis data and precipitation data from weather stations during 1960-2015. The results indicate that there were remarkably interdecadal abrupts for the summer SAH intensity, area, south border, east point, west point and ridge line. Meanwhile a remarkably interdecadal variation of the summer precipitation in the Middle and Lower Reaches of Yangtze River also occurred. The SAH ridge line had the best correlation with the summer precipitation in the Middle and Lower Reaches of Yangtze River, showing a significant negative correlation. During the periods of summer SAH ridge line interdecadal southern, the SAH was relatively large and strong, and the upper air flow in the Middle and Lower Reaches of Yangtze River was strong and divergent. While the West Pacific Subtropical High increased westward extension, and there was a stable low pressure covered India. The Middle and Lower Reaches of Yangtze River located in the northwest side of the subtropical high and in front of the westerly trough where the prevailing southwest wind met the westerly airflow. The wind field in the lower layer had obvious shear and convergence, and the water vapor transported from the Bay of Bengal and the South China Sea converged and rose in the Middle and Lower Reaches of Yangtze River, resulting in heavy precipitation. From the early 1990 s to the early 2000 s, the summer SAH weakened and retreated in the west, while the subtropical high weakened in the east. However, due to the small degree of weakening of the two high pressures, the summer precipitation in the Middle and Lower Reaches

关 键 词：南亚高压 长江中下游 降水 年代际变化 脊线 

分 类 号：P46[天文地球—大气科学及气象学]