Analysis And Research On The Characteristics Of Water Vapor Source Of Precipitation In Xinjiang

Xinjiang is located in the northwest of China,on the abdomen of Eurasia.The terrain is very complex.It is an arid and semi?arid area which is not affected by the monsoon.However,in the Xinjiang area,rainstorms are common occurrence,often causing various secondary disasters that brought life and economic damage to the Xinjiang people.Water vapor is the primary condition for the formation of heavy rain.In arid and semi-arid regions such as Xinjiang,the study of water vapor sources is particularly important.Based on the observational data from the China Meteorological Bureau and reanalysis data from the ECMWF and NCEP,This article uses the statistical methods and the Lagrangian particle dispersion model FLEXPART to reveal the characteristics of the water vapor source in Xinjiang.Firstly,the Lagrangian particle dispersion model FLEXPART is used to simulate the particle distribution of the simulated area during the the period of 2008?2015.The characteristics of the water vapor source of Xinjiang in winter and summer and variation are analyzed by the simulated data.The results show that the water vapor source area of Xinjiang precipitation is mainly located in the continent and Ocean on the west of Xinjiang,and the major source area of water vapor is in the continental area,especially in the local area and Central Asian areas.The source area of water vapor of Xinjiang is north distribution in summer and south distribution in winter,this distribution pattern was caused by the change of the North Atlantic subtropical high,which resulted in the change of the water vapor transport zone in Eurasian continent.Secondly,the applicability of the Lagrangian particle dispersion model FLEXPART is analyzed by comparing with the actual data,and the water vapor transport and the characteristics of the water vapor source are analyzed.The comparison of precipitation and motion trajectory shows that the FLEXPART mode is highly reliable.The results show that the target particle is mainly from the west of the target area,and the vapour water vapor is also transported from the lower layer of the area near Xinjiang.The quantitative calculation for the contribution of water vapor shows that the main sources of water vapor are the local area and Central Asia.However,due to the difference of circulation,the water vapor source area will be different,such as the difference of water vapor source area in the case of two heavy rainfall cases: one case of precipitation is an important source area in North Asia and the other in East Asia.Then,base on the synthetic analysis of multiple cases,the evolution characteristics of water vapor transport and the contribution of water vapor of the precipitation in Xinjiang are analyzed.The results show that the precipitation in Xinjiang is usually had high pressure in ground and low trough in middle layer,and the low layer southwest airflow will accumulate water vapor for precipitation in front of the trough.The western water vapor mainly entered the Xinjiang area through the gap between Tianshan and Altay mountains.The major water vapor of precipitation in Xinjiang is transported through advection,but the contribution of the local area can not be ignored,Central Asia and Xinjiang are the important water sources of Xinjiang.Finally,according to the geographical distribution characteristics of torrential rainfall in Xinjiang,six torrential rainfall study areas were selected for the storm events.The water vapor transport path,the water vapor source area and the water vapor contribution were analyzed respectively.The analysis shows that most of the particle entering Xinjiang come from the mainland and the oceans in the upper reaches of Xinjiang,and the particle with abundant water vapor are generally transported in the lower layers.There are two main sources of water vapor in Xinjiang,namely Xinjiang area and Central Asia.The more northward the location of the rainstorm occurs,the greater affect by North Asia,and more easterly location of the rainstorm occurs,the greater affect by Xinjiang area.