| Information on global energy and water cycle balance depends on accurate precipitation measurement.High temporal and spatial resolution make the satellite rainfall data not only make up for the limitations of station precipitation data but also and play a key role in water management and hydrological simulation.This paper evaluated TRMM 3B42 and GPM Satellite precipitation in the Yangtze River basin from 2003 to 2015.We also studied the spatial distribution pattern and trends of vegetation cover of the Yangtze River basin from 1982 to 2013 by using the NDVI data and analyzed the relationship between NDVI and precipitation by uniting precipitation data.Finally,we analyzed the application of TRMM satellite precipitation data based on NDVI and RUE in the growing season.The results shows that:(1)TRMM satellite precipitation products all have good precision to estimate precipitation in different time scales.V6 and V7 are more consistent with the observed precipitation compared with RTV6 and RTV7.V7 is the best at estimating the precipitation of the Yangtze River basin(bias of most area is ranging from-10% to 10%).The estimate precision of V7 estimation is better than that of GPM in general,but GPM performances better than V7 in January and December.(2)The estimate precision of TRMM satellite precipitation is closely associated with the monsoon climate.The fitness in rainy period in East Asian monsoon is better than it in dry season in the southwest summer monsoon period.For example,the correlation coefficient of V7 is 0.39~0.90 in the East Asian monsoon while correlation coefficient is 0.27~0.89 in the Southwest monsoon period.The precision of TRMM satellite precipitation is also influenced by altitude and terrain,so,it appears a large bias in the source region of Yangtze River.(3)From the spatial distribution,we can see that the vegetation in the Yangtze River basin is in a good condition,especially in the mid and lower reaches,but the condition is poor in the source area of the Yangtze River.The average annual NDVI value in Yangtze River basin is 0.558,and the area where NDVI value greater than 0.6 is up to 45.69%,while the NDVI value lower than 0.2 only accounts for 3.24%,mostly appears in the northeast of Qinghai and Tibet.(4)In the past 32 years,NDVI of the Yangtze River basin shows a trend of significant growth in speed of 0.98%/10 a.The vegetation coverage in upper Yangtze,mid and lower reaches is increasing significantly.The increasing speed of mid and lower reaches is 1.3%/10 a while the upper reaches is 0.75%/10 a.The most obvious increasing trend of NDVI appears in spring,with the increasing speed of 2%/l0 a,while the increasing speed in winter is 0.1%/10 a.(5)The result of spatial distribution pattern and trend of inter-annual variability of RUE which is estimated by V7 is generally close to the observed data,but RTV7 exists obvious error in some areas,especially in the year of abnormal precipitation.In a word,V7 can be used to estimate for RUE preferably.In this paper,the estimation accuracy of TRMM and GPM satellite data in the Yangtze River Basin was evaluated.Combined with the cumulative NDVI of the growing season,the precipitation use efficiency in the Yangtze River Basin was simulated and the application of TRMM satellite precipitation data in the Yangtze River Basin was analyzed.This study not only evaluate the application accuracy of TRMM satellite precipitation data in the large watershed but also provide theoretical support for those regions with rare gauge stations and provide scientific basis for water resources management and regional ecological construction in the Yangtze River basin. |
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