Precipitation Gradient In Tianshan Mountain Area Based On Multi-Source Precipitation Data

Atmospheric precipitation plays an important role in the local water vapor cycle and energy exchange,which is an important material basis for regional ecological protection and economic development.To further study the spatial differentiation and gradient changes of precipitation in the Tianshan area,five types of precipitation data from 2000 to 2018 were selected,and the V2.0 precipitation data in the same period were used as verification data.At the same time,the ECMWF(European Intermediate Weather Forecasting Center)in the study area was selected to analyze water vapor data,the Second Chinese Glacier Inventory and five MODIS remote sensing images in 2016.Firstly,the five coefficients of precipitation data were evaluated using correlation coefficients,root mean square error,precipitation detection rate and other methods,and the error distribution data of the five types of precipitation data in the study area was obtained.Secondly,the data of the five types of precipitation data were analyzed using a linear regression model.After the correction,the five types of precipitation data were spatially interpolated through the weather interpolation software ANUSPLIN and the DEM in the study area.Finally,a more accurate precipitation data set in the study area was obtained,and related research on the precipitation gradient in the Tianshan area was carried out.In addition,the change of the precipitation gradient in the Tianshan area was discussed combined with glaciers,atmospheric water vapor,and vegetation coverage.The main conclusions can be summarized as follows:(1)In terms of time series,the applicability of ITPCAS precipitation data in the Tianshan area is better,and the data accuracy is higher,followed by TRMM precipitation data,and the worst applicability and accuracy is PERSIANN precipitation data.From the perspective of spatial distribution,the best accuracy of the Junggar internal flow area is APHRODITE,the data accuracy of the IMAGE precipitation data in the Yili River Basin good,the optimal data of the internal flow area in the northern Tarim is ITPCAS,and the Turpan-Hami basin is PERSIANN precipitation data.(2)The precipitation and elevation changes of most rivers in the Junggar InlandFlow area showed a linear increase trend,while the precipitation of the Manas River and Urumqi River decreased first and then increased with the change of altitude.The Kashgar River,Toshigan River and Kaidu River in the inland area of northern Tarim had the highest precipitation height zone.There were high-value zones of increasing precipitation in the Aimzarte River and Kuqa River.The precipitation and altitude in the inland area of Turpan-Hami Basin both showed a linear increasing trend.The precipitation in theYili River Basinshowed a trend of decreasing first and then increasing.Among them,the Kashi River and the Kosuk River had the highest possible precipitation height zones,of which elevations were roughly distributed around 1530 m and 2600 m.(3)The five types of precipitation data in the Junggar inner flow area all had a precipitation height zone at 2600 m in all four seasons.The first precipitation highvalue zone in the Yili River Basin appeared around 2060 m,and the second precipitation high-value zone all appeared around 3600 m.The first precipitation high-value zone in Turpan-Hami Basin appeared around 2740 m and the second one was around 3800 m.There were two precipitation high-value zones in the APHRODITE precipitation data in the northern inland area of northern Tarim,the first one was between 2400-3100 m,The second was between 3600-4500 m.(4)From 2000 to 2018,the multi-year average atmospheric water vapor transport synthesis field in the Tianshan area was dominated by westerly winds and northerly winds.The main body of the Tianshan area was the water vapor divergence area,while the Junggar Basin and the west side of the Tianshan area are the water vapor convergence area.In the Turpan-Hami Basin,the water vapor mainly concentrates below 2000 m,that is,the water vapor pressure was higher than 830 HPa.The gradient of water vapor gradient in the inner flow area of northern Tarim was consistent with the change trend of water vapor in the inner flow area of Turpan-Hami Basin,that is,the water vapor content gradually decreases from 2000 m.The water vapor content of the Yili River Basin significantly greater than that of the other three regions,with the highest value exceeding 50 mm.The water vapor content in the Junggar inland area is second only to the Yili River Basin.(5)The glacier balance line of most glaciers in the inland area of Turpan-Hami Basin is consistent with the distribution of precipitation extremes;the altitude of the glacier balance line and precipitation in the northern inland area of Tarim is the most distributed(4200 m).The altitude of the Yili River Basin the Junggar Inland Area are both 4000 m.The distribution height of the forest line in the Tianshan area is 1km higher than the maximum precipitation height;the amount of precipitation is inversely proportional to the forest line height.