Quantitative Study on Water Vapor Pumping over Qinghai-Tibetan Plateau and Water Vapor Paths Influencing Summer Precipitation in the Middle and Lower Reach of the Yangtze River
JING Wenqi;CUI Yuanyuan;LIU Ruixia;WANG Yegui;FANG Hanxian;ZHAO Xiaoyan;MA Jie;College of Meteorology and Oceanography,National University of Defense Technology;School of Atmospheric Science,Nanjing University of Information Science and Technology;Key Laboratory of Radiometric Calibration and Validation for Environmental Satellite National Satellite Meteorological Center,China Meteorological Administration;Institute of Atmospheric Physics,Chinese Academy of Science;School of Applied Meteorology,Nanjing University of Information Science and Technology;
Based on JICA Tibetan sounding data in 2008,ERA-Interim and MERRA reanalysis data during 19792015 and monthly average precipitation of 160 stations in China,firstly this study evaluates the applicability of two reanalysis data on Qinghai-Tibetan Plateau( QTP) and defines the high-level and low-level difference of water vapor flux divergence on QTP as QTP water vapor pumping index; By synthetic analysis,it is found that there are mainly five water vapor paths influencing summer precipitation in middle and lower reach of Yangtze River( MLRYR) : The Bay of Bengal path,Yunnan-Guizhou Plateau path,South China Sea path,lowlatitude path and confluent water vapor path,whose magnitude is calculated by index. The result shows that ERA-Interim reanalysis data shows better applicability than MERRA reanalysis data on QTP. On the inter-annual variability,all the water vapor paths perform the same phase change with MLRYR summer rainfall. Five paths are closely related,making up two anticyclonic water vapor transport correlation-chains: One is "South China Sea-the Bay of Bengal-southern edge of QTP-Yunnan-Gui Zhou Plateau-MLRYR ",the other is "South China Sea-YunnanGuizhou Plateau-MLRYR". South China Sea path is important water vapor channel of the rainfall in east China;Confluent path is the vital water vapor channel controlling the summer rainfall in MLRYR,but Yunnan-Guizhou Plateau path shows significant correlation with the summer rainfall in whole reach of Yangtze River. QTP water vapor pumping,which effects summer rainfall in MLRYR,mainly occurs over southern edge of QTP. QTP water vapor pumping can pump up water vapor in lower level to the top of QTP,and plays an indirect role in influencing the summer rainfall in Yangtze River by increasing zonal water vapor transport towards the Yangtze River Basin.