Research On The Characteristics Of Water Vapor Transport And Its Budget In The Main Water-receiving Areas Of The Central Yunnan Water Diversion Project

Hydrological cycle is an important process of water,matter and energy exchange on the earth,although the water vapor content in the atmosphere accounts for a relatively small proportion of the total water in the global hydrological cycle system,it is the most active part of the global hydrological cycle,and it is also an essential water vapor condition for precipitation formation,its changes affect the structure of global water resource system and the spatial and temporal evolution of precipitation in a region,as well as human social development and production activities.The main receiving area of water diversion project in Central Yunnan is located in the monsoon climate area,affected by the East Asia monsoon,South Asia monsoon and plateau monsoon,with distinct dry and wet conditions.Therefore,the study of water vapor transport and its budget in the main receiving area is of great significance for regional climate anomalies and disaster prevention,and is contributive tostudy the spatiotemporal evolution process of precipitation,abnormal changes and the rational allocation of water resources.Based on ERA-Interim reanalysis data and the station measured precipitation data,this paper analyzes atmospheric process of hydrological cycle in main receiving area of water diversion project in Central Yunnan,and discuss the relationship between water vapor transport and temporal and spatial distribution of precipitation.The main contents and conclusions are as follows:?Temporal and spatial variation of water vapor content in the main receiving area of water diversion project in Central Yunnan.The results show that,the spatial distribution of water vapor content is contrary to the terrain trend,increasing from northwest to Southeast,with significant interannual changes.The annual distribution is single peak,with the highest water vapor content in July and the lowest in January.The seasonal changes are obvious,with the highest water vapor content in summer and the lowest in winter,which are consistent with the seasonal changes of precipitation in the same period.Honghe is the center of atmospheric moisture content of the main receiving area,and the moisture content of Chuxiong and Kunming are very least.In spring and summer,the water vapor content first decreased and then increased.?Characteristics of water vapor transport in the main receiving areas of the water diversion project in Central Yunnan.The results show that,the water vapor transportation is mainly in the latitudinal directionin the main receiving areas of the water diversion project in Central Yunnan.Moisture sources change with season movement.In spring,the water vapor comes from the north of the Bay of Bengal and the West Pacific Ocean.In summer,the water vapor source of the main receiving areas which is controlled by the southwest monsoon comes from the water vapor flow of the bayof Bengal and the Indian Ocean.While in autumn,moisture mainly comes from the Bay of Bengal and the South China Sea area,the west of the study area is controlled by the southwest wind,the water vapor transportation intensity in the north is greater than that in the south,and gradually weakens from the north to the South,while in winter primarily from the high latitude region.The water vapor transport intensity showed a decreasing trend,and the transport flux isoline gradually moved southward in May to July.Influenced by South Asia high pressure and India low pressure,the water vapor transport intensity reached the maximum value in July.In July,on the 850h Pa,there is a water vapor convergence center in the south of the study area,while on the 450hpa,the southwest of the study area is a water vapor convergence belt,so the southwest is prone to the formation of precipitation and abundant in summer.?Water vapor budget and its changing characteristics in the main receiving areas of the water diversion project in Central Yunnan.The results show that,the annual average total water vapor input is 270.15km~3,the total water vapor output is 264.86km~3,and the net input is 5.29km~3in the main receiving areas of the water diversion project in Central Yunnan,in most years,the water vapor budget shows"surplus",and the net water vapor budget shows an upward trend year by year;The west boundary is the main input boundary of water vapor,and the east boundary is the main output boundary of water vapor.The seasonal difference is obvious,the water vapor budget in rainy season is"+",which shows"surplus",while in dry season is"-",which shows"deficit";the water vapor budget shows"deficit"in spring and winter,while it shows"surplus"in summer and autumn.The net input of water vapor increased in four seasons.?Spatial and temporal distribution of precipitation and relationship between water vapor transport and spatial and temporal distribution of precipitation in the main receiving areas of the water diversion project in Central Yunnan.The results show that,the spatial distribution of precipitation is uneven,and the local difference is large,which is characterized by"summer,autumn,spring and winter".The precipitation in summer is the most,while the precipitation in winter is the least,the precipitation in rainy season accounts for 80%-90%of the whole year.Honghe has the largest precipitation in all seasons,Chuxiong has the least precipitation in spring and winter;the precipitation in spring and summer has a downward trend,and the downward trend in spring is greater than that in summer;the precipitation in autumn and winter has an increasing trend,and the increasing trend in winter is atmospheric autumn.There is a good correspondence between moisture content,the net moisture gain or net moisture loss,moisture flux,water vapor flux divergence and precipitation distribution in the main receiving areas.