Evaluation And Application Of Satellite Precipitation Estimation Products In Central Asi

In-depth study of the characteristics of precipitation and its temporal and spatial distribution characteristics in the five Central Asian countries is not only of great scientific significance,but also helps to improve the service and guarantee capacity of China’s "Belt and Road" strategy.Satellite remote sensing is the only effective way to obtain high-spatiotemporal resolution precipitation in the five Central Asian countries in a timely manner,and the accuracy of satellite precipitation products is systematically evaluated before the research is carried out.In this study,four satellite precipitation products-CMORPH,FY4 A,GSMa P and IMERG were selected,and the comprehensive evaluation method was adopted to evaluate each product in detail with quantitative and qualitative indicators and extreme precipitation indicators,and the "optimal" product IMERG was obtained.On this basis,based on the specific analysis of precipitation characteristics and their temporal and spatial distribution characteristics in five Central Asian countries based on IMERG products,the main conclusions are as follows:(1)Whether it is an annual,seasonal or monthly scale,the precipitation of the four satellite precipitation products is overestimated,and the overall performance is the IMERG product,which has a high and stable correlation coefficient CC and a low rms error RMSE and relative deviation BIAS.(2)CMORPH products and IMERG products have a strong ability to capture precipitation in the 0-5 mm/day range,while FY4 A products and GSMa P products are more sensitive to precipitation capture in the 5-20 mm/day range.The qualitative evaluation results of IMERG products at each altitude were generally better than those of other satellite precipitation products,while CMORPH products had the worst evaluation results in different qualitative indicators.The optimal distribution of products to assess extreme precipitation is fragmented and not concentrated on one product.(3)The areas with obvious interannual changes in precipitation in the five Central Asian countries were mainly concentrated in areas with more and less annual precipitation,and the spatial distribution of annual average precipitation varied greatly,and most of the areas were less than 200 mm.Kyrgyzstan receives relatively more average annual precipitation,followed by eastern Tajikistan and east-central Kazakhstan,and less in Uzbekistan and Turkmenistan.The average annual precipitation in the five Central Asian countries is closely related to altitude,and the average annual precipitation in low-altitude areas is very different from that in highaltitude areas.(4)The five Central Asian countries have obvious seasonality in terms of precipitation,precipitation range and spatial distribution of precipitation,with the most precipitation in spring,the widest precipitation range,the least precipitation in autumn,and sufficient precipitation in Kyrgyzstan and Tajikistan in all seasons.The spatial distribution of the average monthly precipitation in the five Central Asian countries was roughly divided into three distribution forms: arid,semi-dry and semi-humid and humid.The five Central Asian countries are dominated by light rain,followed by moderate rain,heavy rain and heavy rain,and the contribution of precipitation mainly comes from the frequency of precipitation rather than its intensity.(5)The precipitation indicators in the sub-regions of the five Central Asian countries are different,but there are common points,and extreme precipitation shows the unevenness of temporal and spatial distribution.