The Characteristics Of Water Vapor Transportation And The Contribution Of Water Vapor Source Of The Rainstorm Caused By Cold Vortex Over Northeast China

Northeast cold vortex is an important weather system in northeast China; the rainstorm caused by the cold vortex has a heavy impact on the economic and agricultural development in northeast China region. Based on daily precipitation data in northeast China, the northeast cold vortex calendar table and the NCEP/NCAR reanalysis data from1961to2010, this study researched the northeast cold vortex of climatology features, the relationship with atmospheric circulation, the characteristic of water vapor transportation and the water vapor contribution of water vapor source to rainstorm. Main conclusions are as follows:1The heavy rain caused by northeast cold vortex mostly happened in summer, and42.2%of the total number of them were in July; the annual variation of the days of cold vortex rainstorm showed the rising trend which was not obvious, the days of cold vortex rainstorm occurred from2004to2005by changeable fewer mutations. The annual variability of the days of cold vortex rainstorm had18year’s period and3-5year’s remarkably small scale period. Heavy rain mainly concentrated in the southeast of northeast China, the incidence of extreme precipitation was higher in the Liao River and Yalu River watershed.2In the northeast cold vortex rainstorm period, the zonal water vapor fluxes were significantly higher than normal years at the bay of Bengal, the south China sea, the region from east China and yellow and bohai sea to the west of the Pacific Ocean near30°N. Southeast region in northeast China was a water collection area.Cold vortex rainstorm mostly happened in the southeast and southwest of cold vortex activity center. The days of Cold vortex rainstorm were significantly positively related with the location of western Pacific subtropical high system, southwest monsoon’s activity and the southeast monsoon activity, while were significantly negative correlation with the north monsoon area and west wind system activity.3There were four main water vapor sources of cold vortex storm in the northeast:(1) the Eurasian continent, especially the area near Lake Baikal;(2) the sea of Okhotsk, the sea of Japan, the yellow and Bohai Sea and western Pacific Ocean, collectively known as the west Pacific and the adjacent waters;(3) Indian Ocean and the sea area from bay of Bengal to the south China sea, collectively known as the bay of Bengal-south China sea;(4) the northeast China. Among four water vapor sources, the Eurasia continent main transported dry cold air block in high layer of atmosphere (above1500m), and the tropical and subtropical ocean area transported warm moist air block in low layer of atmosphere (below1500m).The water vapor contribution rate of Western Pacific (including the sea of Okhotsk, the sea of Japan, yellow sea and bohai sea and the east China sea) was39.8%; Followed by the sea area from bay of Bengal to south China sea, the water vapor contribution rate was32.1%; the water vapor contribution rate of Eurasia continent was20.9%; the water vapor contribution of northeast China was minimum, the contribution rate of which was7.2%.The relevant inspection of water vapor contribution rate and circulation index of water vapor sources were proceed, and then the regression equation were established, the result showed that the regression equations were all through significance test. The water vapor contribution of Eurasia continent and north monsoon area index and west wind index were significantly related, and the fitting effect of regression equation was good.