四川盆地及周边地区TRMM 3B42数据精度检验

Accuracy validation of TRMM 3B42 data in Sichuan basin and the surrounding areas

多源信息融合的流域水文模拟及预报技术,是目前水文预报发展的一个重要方向。以易发生长江流域特大洪水的四川盆地及周边地区为研究区域,从单个站点及子流域降水量相关性、降雨空间分布和相对误差等方面对TRMM卫星3B42产品探测精度进行了检验分析。结果表明:研究区TRMM 3B42数据与地面观测数据在日、月尺度上具有较高的相关性(R>0.5),3 h尺度相关性较差(R<0.5),且3 h和日尺度在降水量峰值拟合上存在较为明显的数值偏差和时间上的提前或延迟;不同时间尺度下两组数据的空间分布特征总体具有较好的一致性;两组数据2008—2010年降水量序列均值相对偏差在±10%的概率密度百分数为32.26%。总体上研究区TRMM3B42数据呈现高估(四川盆地大部分区域),局部出现低估(四川盆东南及地周边地区);研究区3 h尺度TRMM 3B42数据探测精度明显低于日尺度,高程变化对TRMM 3B42数据的探测精度具有一定影响。因此,针对该区域TRMM 3B42数据3 h和日尺度数据序列精度相对较差的问题,应用该卫星数据进行3 h尺度流域水文模拟及预报研究时,就需要对该区域卫星数据和地面观测数据进行融合,充分发挥两种数据的优势。

Merging multiinformation is a very important developing direction about hydrology model ing and prediction these days. Thereby, TRMM 3B42 data and rain gauges are adopted to engage in ac curacy validation in Sichuan Basin and the surrounding areas as the study area because of frequent occur rence of devastating floods in the Yangtze River basin and this paper refers to correlation, spatial distribu tion, and bias due to elevation, based on single ground station rainfall and subbasin area precipitation. The results indicate that the daily and monthly correlation coefficient between TRMM 3B42 data and rain gauges rainfall is quite high （ R 〉 0. 5 ）, but it is low （ R 〈 0. 5 ） for 3h scale. There are significant devi ations about 3hourly and daily scales. Precipitation spatial distribution has good consistency betweenthese two group data for different temporal scales. Probability density percentage of mean rainfall time se- ries bias is 32.26% ± 10% from 2008 to 2010. TRMM 3B42 data are overestimated in most regions of Sichuan basin in the mass, but underestimated in the partially surrounding areas of Sichuan basin. The detection accuracy of 3-h scale＇s TRMM 3 B42 data is significantly lower than that of daily scale, and it is influenced to a certain extent by the elevation changes in the whole region. Because 3-h and daily scales of TRMM 3B42 data have no good precision, they need to be calibrated by the rain gauges, in order to use these data in hydrology modeling and prediction research.