Study Of Characteristics Of Air Cloud And Water Resource In Northwest China

Energy and water cycle are important processes in the global climate system.Cloud is an important part of water vapor conversion and precipitation,and plays an important role in climate change and weather analysis.The spatial and temporal variability of precipitation in the northwestern region is large and water resources in the northwestern region are scarce,which restricts the economic and social development.Carrying out weather modification and rational development of cloud water resources in the sky is an effective means to increase water resources in the region.In this paper,ECMWF and CERES grid data are used to reanalyze the precipitation,clouds,and water vapor in the Northwest China from 1990 to 2016.The main conclusions are as follows:(1)The spatial distribution of precipitation in the northwestern region is extremely uneven,and the precipitation in the southeastern region is more than 500 mm.During this transition from the edge of the southeast monsoon region to the inland west,the rainfall drops sharply to less than 50 mm in the western part of Gansu Inner Mongolia and Xinjiang.The precipitation in Tianshan,Kunlun Mountains,and Qilian Mountains is more than that in the surrounding areas.The results of EOF analysis show that the spatial distribution pattern of annual(seasonal)precipitation is mainly uniform in the whole area,and the contribution rate of the three-mode variance before the annual precipitation is close to 50%,as well as in spring,summer and autumn.The 2 modal variance contribution before winter is close to 70%.(2)The amount of atmospheric precipitable water in the southeast of the northwest region(Ningxia,Shaanxi,Shanxi,etc.)is relatively large,reaching 6,000 kg·m-2,gradually decreasing from southeast to northwest,south of Qinghai,Tianshan,Kunlun Mountains,Qilian Mountains and The amount of precipitable water in the west of Gansu and Inner Mongolia is less than 2000 kg·m-2.In summer,the amount of precipitable water accounts for the largest proportion in the whole year,except in Xinjiang and Gansu,where most of the area is more than 50%.In autumn,it is slightly more than in spring,and the amount of precipitation in winter is least.The precipitation efficiency in the southeast is less than10%,and the precipitation efficiency in the mountainous area is relatively high.Tianshan,KunlunMountains and Qilian Mountains reach more than 15%.Precipitation efficiency is larger in spring and similar in summer,autumn,and smaller in winter.The overall efficiency of precipitation is not high,and the actual utilization of water vapor resources in the air is low and the development potential is great.(3)Analysis of several key sub-regions shows that:a.Precipitation in the Region Tianshan(Tianshan and northern Xinjiang)was the largest in the summer but showed a downward trend,followed by the increase in the spring and autumn;the inter-annual variation in the amount of precipitable water was not significant,the summer was the highest,and the precipitation efficiency was about 5%.Water resources development potential.b.Precipitation in Region Qilian(Qilianshan and its surrounding area)is relatively low,with a maximum of less than 20 mm in summer.There is a slight decrease in precipitation during the four seasons.The amount of precipitation is relatively large and increases year by year.Precipitation efficiency is higher in spring and summer,but Less than 5% can use more water vapor.c.Precipitation in Region Nan Jiangxi(Kunlun Mountains and West South Xinjiang)is more in spring and summer,reaching 30 mm,and it is less in autumn and winter.In addition to the fall,the precipitation has a tendency to decrease;the inter-annual variation of precipitable water is stable;the precipitation efficiency is 10% but there is a downward trend.d.In Region Shaan Ninghe(Northern Shaanxi,Ningxia and Hetao areas),the precipitation is highest in summer,followed by spring and autumn,and the precipitation has a decreasing trend;the amount of precipitable water has little change from year to year,and there is an increasing trend in summer and autumn;the precipitation efficiency is about 5%.There is a downward trend in spring and summer.(4)The conditions of water vapor transport,revenue and expenditure at each boundary of different regions are different:(1)Region Tianshan is a water vapor output zone,and the west boundary is mainly water vapor input,and the water vapor output at the east boundary and the south boundary,and the input and output volumes in summer and autumn are rich;(2)Region Qilian is a water vapor output area,and the west and north boundaries are mainly water vapor input,the south boundary and east boundary water vapor output,and the summer water vapor is active;(3)In Region Shaan Ninghe water vapor output area is mainly water vapor input on the west and north borders,and the water vapor output on the south and east borders.The changes in the spring,summer,and autumn budgets are relatively large.(5)The cloudiness of cumulus,stratus,stratiform clouds,and stratus clouds is relatively small.The cumulus and stratus clouds reach only about 10% in summer in individual regions,and the difference in cloudiness during periods of high or low precipitation The value is less than 6% as a whole.There is a large difference in the amount of high-level cloud,clouds in the Tianshan Mountains in the summer andthe Kunlun Mountains in the autumn and winter.Cumulonimbus clouds have a large difference in the amount of clouds in Qilian Mountains and Kunlun Mountains in spring.Different types of clouds have different spatial distribution characteristics of precipitation in different seasons.There are positive correlations between cumulonimbus and rain clouds in Tianshan,Kunlun Mountains,and Qilian Mountains.The significant regional correlation coefficient can reach 0.482.Areas that are significantly tested are small and scattered.(6)Between 2000 and 2016,the number and fluctuation of cloudiness in the four seasons in the sub-regions are significantly different:(1)Region Tianshan and Region Xin Jiangnan,the amount of cloudiness is relatively large in autumn and winter,over 14%,and there is a clear trend of growth over time.There are more high-level cloud clouds in spring and summer and tend to decrease with years.(2)In region Qilian,there are more cumulonimbus clouds in spring,which are more than 10%,and there is an obvious increase trend.In summer,the amount of high-level,high-product and cumulonimbus clouds is similar and has a tendency of slight decrease.