Spatial And Temporal Distribution,Source And Availability Assessment Of Water Vapor Resources In The Arid Region Of Central Asia

Atmospheric water vapor is an important part of the atmosphere.Water vapor content plays an important role in regulating global radiation budget,energy balance,stratospheric temperature and chemical process,and global climate change.The arid region of central Asia is located deep in the hinterland of the Eurasian continent,and is the widest arid zone in the middle and high latitudes of the Northern Hemisphere.Water resources are very scarce,and water resources play a very important role in the socio-economic and ecological environment construction of the region.This study takes the arid region of central Asia as the research area,compares ERA5,JRA55,CRA-40,and MERRA-2 data,selects the optimal ERA5 data,uses the atmospheric water vapor content（TCWV）data from the 1979 2020 European Medium Range Weather Forecast Center ERA5,and compares the results with other datasets to analyze the spatiotemporal distribution of water vapor resources in the arid region of central Asia from 1979 to 2020.The HYSPLIT model is used to analyze the source of water vapor in the arid region of central Asia,And use the precipitation data from the arid region of central Asia during the same period to calculate the precipitation efficiency of water vapor resources,and evaluate its availability.The results are as follows:（1）Analysis of the spatial and temporal characteristics of the Central Asian arid zone from 1979 to 2020 based on ERA5 data yields:the water vapor content in the study area is mainly distributed between 2-26 kg-m^-2,and in terms of spatial distribution:the high value areas are concentrated in southwestern Tajikistan and southwestern Kazakhstan,where the water vapor content is abundant,with the highest The seasonal spatial distribution of water vapor content is basically the same as the annual average spatial distribution,with the highest total water vapor content in summer,followed by spring and autumn,and the lowest in winter.The annual and seasonal averages of water vapor content for 1979-2020 were calculated using JRA55,CRA-40,MERRA-2 data sets,and the results were more consistent.（2）The seasonal distribution of cloud liquid water content and cloud ice water content in the arid region of central Asia shows a characteristic of high in the northwest and low in the southeast,while the cloud ice water content in each season shows a characteristic of high in the central region and low in the rest of the region.From 1979to 2020,the average high value areas of cloud liquid water were mainly distributed in the northwest of Kazakhstan,with a maximum value of 0.08kg·m^-2.The low value areas were distributed in Tajikistan,eastern Kyrgyzstan,Xinjiang,China,and most of Gansu,with a minimum value of only 0.02kg·m^-2;From 1979 to 2020,the average cloud ice water high value area was distributed in northern Tajikistan and western Kyrgyzstan,with a maximum value of 0.06kg·m^-2.The low value area was distributed in Kazakhstan,Uzbekistan,western Turkmenistan,Xinjiang,China,and some regions of Gansu,with a minimum value of only 0.01kg·m^-2（3）From the time distribution:1979 to 2020,the overall trend of water vapor content is increasing,cloud ice water content is decreasing,and cloud liquid water content is decreasing;water vapor content is increasing in spring,decreasing in summer,increasing in autumn,and increasing in winter.（4）2006-2021 annual average and seasonal average high value of central Asia arid zone water vapor sources are mainly the Atlantic Ocean,the Mediterranean Sea and the Black Sea and other long-distance channel,low value zone by topographic factors,water vapor sources are mainly Asian and European continents and other proximate influence is large;water vapor content is affected by the westerly wind.（5）Based on the precipitation and water vapor content of the central Asian arid zone from 1979 to 2020,the precipitation efficiency of water vapor resources in the central Asian arid zone from 1979 to 2020 was calculated as follows:the overall precipitation efficiency of the central Asian arid zone showed an increasing trend,and the natural precipitation efficiency of water vapor resources was maintained at about 2%in the past 40 years,and the high value of the annual average distribution of precipitation efficiency was concentrated in the western part of Kyrgyzstan,the central and western part of Tajikistan and the western part of Xinjiang,China,while the precipitation efficiency was low in the rest of the study area.