基于TRMM卫星产品的长江流域降水精度评估

卫星降水产品在降水空间格局分析中扮演着重要角色。为分析卫星降水产品在长江流域的应用精度,利用2003~2010年长江流域175个雨量站实测降水资料检验了同期TRMM(Tropical Rainfall Measurement Mission)降水产品3B42 RTV7及V7的精度。结果显示:(1)长江流域年平均降水总量从东南向西北呈现明显的梯度变化,年降水量从2 000 mm/a减少到400 mm/a,降水空间差异极大,时间分布也不均。(2)RTV7和V7降水产品能够捕捉到长江流域降水空间分布格局,尤其是V7在长江流域有较高的精度,对59.85%流域面积的估算偏差在-10%~10%之间;实时产品RTV7在长江上游存在明显的高估现象,偏差大于50%的流域面积高达33.51%。(3)长江中下游RTV7和V7日降水数据与对应的实测数据相关系数都大于长江上游地区,偏差更小。(4)RTV7和V7降水产品在丰水期的估算精度整体优于枯水期。

Accuracy evaluation of precipitation analysis in Yangtze River basin based on satellite TRMM

Satellite precipitation product plays an important role in analyzing precipitation distribution. To assess the application accuracy of satellite TRMM in the Yangtze River Basin, the precipitation data from 175 rain gauge stations during 2003 and 2010 are used to verify the precipitation accuracy estimated by TRMM（Tropical Rainfall Measurement Mission）precipitation product 3B42 RTV7 and V7. The results show that:（1）The precipitations in the Yangtze River Basin distribute unevenly and there is an increasing gradient of annual precipitation over the Yangtze River basin from northwest (< 400 mm/a) to southeast (> 2000 mm/year); (2) RTV7 and V7 products can capture the spatial and temporal distribution of precipitation in Yangtze River basin, especially for product V7, the area percentage of best performance (bias ranging from -10% ~ 10%) of the annual mean precipitation reaches 59.85%. However, obvious overestimation appears in the upper Yangtze River basin for the product RTV7 and the area percentage of obvious overestimation (bias > 50%) for the annual mean precipitation reaches 33.51%; (3) The estimation accuracy of RTV7 and V7 precipitation products in the upper Yangtze River basin is lower than that of in the mid-lower basin; and the performance of these two products in the wet period is better than that in the dry period.