Characteristics Of The Water Vapor Transport In Both Strong And Weak Summer Monsoon Year And Physical Mechanisms Of Vapor Transportation

The vapor flux integrated from the earth surface up to the top of the atmosphere is analyzed by using the NCEP/NCAR reanalysis data both in strong summer monsoon years(1994,1990,1985) and weak summer monsoon years(1998,1995,1991) in East Asia. A method quantifying the path of water vapor transport is put forward in this paper, and characteristics of water vapor transport over East Asia in strong and weak summer monsoon years are investigated. Our results are summarized as follows:(1) In strong summer monsoon years, the average seasonal distribution of water flux show that the water path of water vapor transport is from Indian Ocean to South China Sea along parallel circles ,then to East Asia along the southwest to the northeast. In the weak monsoon years, the average seasonal distribution of water flux show that the water path of water vapor transport is from the southwest to the northeast along the main land . The water vapor transmission is through the main southern China and the middle and lower reaches of Yangtze River .In the strong monsoon years, the paths of the water vapor transportation is clearly easterly and southerly. The differences of the eastest path in the strong monsoon years and the westest path in the weak monsoon years is about is 7-8 longitudes.in the weak monsoon years the path is parabolic, the water path of water vapor transport is from the southeast to the northeast, then from the southwest to the northeast, finally arrives at Yangtze River valley .Compared with the strong summer monsoon years ,the path of water vapor transport is clearly westerly and northerly. the results show that the anomalies of water vapor transportation is associated directly with atmosphere circulation anomalies. (2) In the strong monsoon years, the position of the western end of the ridge of the Western Pacific Subtropical is easterly and northerly, Ural Blocking High is fallow, the center position of the South Asian High is westerly, the location of the South China Sea summer monsoon trough is northerly ; In the weak monsoon years, the position of the western end of the ridge of the Western Pacific Subtropical is westerly and southerly, Ural Blocking High is activity, the center position of the South Asian High is easterly, the location of the South China Sea summer monsoon trough is southerly. the water vapor transport in South China Sea is associated with the sea temperature, it is associated with the water vapor of Western Pacific and Indian Ocean.Fluxes of the vertically integrated water vapor from the earth surface to the top of the troposphere in the South China Sea is on 30～70d time scale.