Hydrological evaluation of the TRMM multi-satellite precipitation estimates over the Mishui basin
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摘要: 采用地面雨量站点观测降水作为基准数据，评估热带降雨观测计划（TRMM）最新一代卫星降水产品3B42V7的精度；利用站点和卫星两种降水数据驱动栅格新安江模型，采用SCEM-UA算法考虑模型参数不确定性，进行流量过程模拟，评估TRMM 3B42V7在流域水文模拟和预报中的应用能力。数据精度评估显示：在平均意义上，TRMM 3B42V7日降水精度较高，较站点观测低估了6.68%；但在绝对值意义上，TRMM 3B42V7日降水精度较低，绝对偏差达到57.76%；TRMM 3B42V7经过了地面月降水量偏差校准，其精度在月尺度上有较大提高。径流模拟结果表明：TRMM 3B42V7模拟的日径流过程精度较低，有部分洪峰没有捕捉到，但仍能表征径流的日变化特征；月尺度上模拟径流与实测径流吻合较好，能表征径流的季节性和年内变化特征；计算的日尺度和月尺度95%置信区间包含大部分实测流量过程。Abstract: This study aims to evaluate the rainfall estimation accuracy and hydrological potential of the updated Version 7 Tropical Rainfall Measuring Mission (TRMM) multi-satellite precipitation product (TRMM 3B42V7, post-real-time estimates). First, the TRMM 3B42V7 precipitation estimates were compared and validated against the ground rain gauge observations from Jan. 2003 to Dec. 2008. Then, the TRMM 3B42V7 precipitation product was applied to drive the Gridded Xinanjiang model for streamflow simulation and the SCEM-UA algorithm was utilized to analyze and diagnose the model parameters uncertainty. At daily scale, 3B42V7 shows a better performance with lower mean error and bias (only about 6.68% underestimation). However, in terms of the absolute error sense, its data accuracy was not performed as expected (approximately 57.76% of absolute bias). At monthly scale, the TRMM 3B42V7 estimates have been improved dramatically by the month-to-month gauge adjustments during the data processing algorithm. The simulating accuracy of the daily streamflow driven by TRMM 3B42V7 is not satisfactory in the common sense for missing some flood events, but it can still capture the diurnal variation of the streamflow. By contrast, the TRMM-driven streamflow simulation performs better at monthly scale relative to the daily scale. Furthermore, it is capable to represent the seasonal and inter-annual variations of the streamflow. The daily and monthly 95% confidence intervals contain most of the measured streamflow process. This work was anticipated to provide the insights to the hydrologic user community when applying the TRMM satellite precipitation products for water resources simulation and management, especially over ungauged or data-scarce basins.
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