红河流域TRMM卫星降水数据精度评价

利用红河流域及周边地区45个气象站点1998-2015年实测降水数据,在不同时空尺度上对TRMM3B43V7卫星降水数据进行精度评价,并分析高程、坡度和坡向对降水数据精度的影响。结果表明:在年尺度上,TRMM降水数据与站点实测降水数据拟合优度R~2为0.75,整体上TRMM降水数据比站点实测降水数据偏高7.73%,月尺度上,TRMM降水数据与站点实测降水数据拟合优度R~2为0.84,两者之间相关性显著,季尺度上,春季降水拟合优度(R~2=0.77)高于其余3个季节,冬季降水拟合优度最差(R~2=0.64);流域尺度上,降水重心移动轨迹表明TRMM降水数据基本能反映降水的空间分布及演变过程,站点尺度上,各站点的相关系数均大于0.84,相对偏差较大的站点主要分布在河谷和盆地地区;TRMM降水数据在海拔大于1 000 m、坡度小于2°以及东南方向上的精度较高;主成分分析方法表明坡度和坡向对TRMM降水数据精度的影响大于高程。

Accuracy evaluation of TRMM satellite precipitation product over the Red River basin

The precision of TRMM 3B43V7 satellite precipitation data were evaluated at different temporal and spatial scales based on the observed data from 45 meteorological stations in the Red River Basin and surrounding areas from 1998 to 2015. The impact of elevation, slope angle and slope aspect on accuracy of TRMM precipitation data were also analyzed. The results showed that: at the annual scale, the goodness of fit between TRMM estimates and the measured precipitation data was 0.75, and the former was 7.73% higher than the latter overall. Meanwhile, at the monthly scale, the goodness of fit between the two data was 0.84, the significant correlation was found between them. At the seasonal scale, the goodness of fit of precipitation (R²=0.77) in spring was higher than that in other three seasons, and goodness of fit for winter precipitation was the weakest (R²=0.64). At the catchment scale, precipitation focus movement showed that TRMM precipitation data can basically reflect the spatial distribution and evolution process of precipitation. At the site scale, the correlation coefficients of all stations were higher than 0.84 and stations with relatively large bias were mainly distributed in valley and basin areas. The accuracy of TRMM data was relatively high over the region where elevation was higher than 1000 m, slope was less than 2° and in the southeast direction. Principal component analysis showed that the influences of slope and aspect on the accuracy of TRMM data were greater than that of elevation.