Study On Climate Characteristics And Variations Of Atmospheric Precipitable Water In The Region Of Inner Mongolia

Inner Mongolia affected by the temperate continental climate and the monsoon climate of medium latitudes had the distinguished climate conditions, the obvious precipitation variability and the shortage of water resources, which seriously restrict the economic and social development and were under enormous pressure to protect ecological and environmental. As an important condition of extreme weather events occurrences, Atmospheric precipitable water was a very important component in the earth atmosphere system. Studying climate characteristics and variations of atmospheric precipitable water was a major content of climate change research, which could provide the important references for the weather analysis, the application of numerical model, and the weather modification operation decision analysis and effect test the important reference.In this research, based on the daily NCEP/NCAR reanalysis data from1981to2010and the ground observation data of117weather stations in Inner Mongolia, using natural orthogonal decomposition (EOF), trend analysis and other methods, the availability of NCEP/NCAR reanalysis data in Inner Mongolia and the climate characteristics and variations of atmospheric precipitable Water, the water vapor transportation, water vapor budgets, the atmospheric precipitable capacity over inner Mongolia were initiatively researched.The results were as follows. In recent30years, the interannual variation of annual mean atmospheric precipitable water in Inner Mongolia showed an unimodal distribution characteristic. The annual mean atmospheric precipitable water in1998was the maximum in recent30years. And the annual mean atmospheric precipitable water was in a slowly increasing change tendency overall. The annual mean atmospheric precipitable water between1981and1998was in a increasing trend, while the data from1998to2010was in a faster reducing trend. The value of summer atmospheric precipitable water was much bigger than the other three seasons. The variation tendency of summer could majorly impact the annual trend.In Inner Mongolia, the annual mean and seasonal atmospheric precipitable water increased from northwest to southeast. On the south edge of Yinshan mountain and on the east edge of Daxinganling mountain, the atmospheric precipitable water values were much bigger than the other sides. Atmospheric precipitable water spatial distribution had a significant seasonal variation. The values of both the atmospheric precipitable water and precipitation were biggest in summer, smaller in spring and autumn, least in winter. Atmospheric precipitable water was one of the main factors to impact precipitation distribution difference in Inner Mongolia, the distribution of which was close positively correlated to the precipitation distribution. The values of atmospheric precipitable water over Hetao area were becoming higher in Inner Mongolia from2001to2010.The annual mean and seasonal atmospheric precipitatable spatial distribution in Inner Mongolia could be decomposed into three major modal types by EOF:the unanimous variation from west to east, east change opposite to west change, hetao area opposite to other area. The first modal types occurred in annual mean and four seasons. The second model types occurred in annual mean, spring, summer and autumn. The last model types took place in annual mean and summer.The water vapor imported from the west boundary and the south boundary in summer, while in the other three seasons, the water vapor mainly came from the west boundary and the north boundary. In the summer, most areas of Inner Mongolia were water vapor convergence zone. The main net water vapor import source of Annual mean, spring, summer and autumn was from the north-south direction, while the east-west direction was net export. In winter, the main contributor of water vapor import was the east-west direction, while the north-south direction was net export. Annual mean and seasonal west boundary was the water vapor import boundary, with the maximum value. Annual mean and seasonal east boundary was the water vapor export boundary, with the maximum value. The water vapor over Inner Mongolia came from two source. One was the direction from southwest to northeast that was the main direction maintaining in summer. The origin was the bay of Bengal. The other was the northwest-southeast direction which was existed in spring, summer and autumn. The annual mean water vapor budget of Inner Mongolia was net input with summer value maximum, next spring, winter again, fall at least. In theory in Inner Mongolia, in spring and summer, there existed high water vapor condensation rate, with abundant potential water resource in the atmosphere.