Evaluation of Latest TMPA and CMORPH Precipitation Products with Independent Rain Gauge Observation Networks over High-latitude and Low-latitude Basins in China

The Tropical Rainfall Measuring Mission(TRMM) Multi-satellite Precipitation Analysis(TMPA) and National Oceanic and Atmospheric Administration(NOAA) Climate Prediction Center(CPC) morphing technique(CMORPH) are two important multi-satellite precipitation products in TRMM-era and perform important functions in GPM-era. Both TMPA and CMORPH systems simultaneously upgraded their retrieval algorithms and released their latest version of precipitation data in 2013. In this study, the latest TMPA and CMORPH products(i.e., Version-7 real-time TMPA(T-rt) and gauge-adjusted TMPA(T-adj), and Version-1.0 real-time CMORPH(C-rt) and Version-1.0 gauge-adjusted CMORPH(C-adj)) are evaluated and intercompared by using independent rain gauge observations for a 12-year(2000–2011) period over two typical basins in China with different geographical and climate conditions. Results indicate that all TMPA and CMORPH products tend to overestimate precipitation for the high-latitude semiarid Laoha River Basin and underestimate it for the low-latitude humid Mishui Basin. Overall, the satellite precipitation products exhibit superior performance over Mishui Basin than that over Laoha River Basin. The C-adj presents the best performance over the high-latitude Laoha River Basin, whereas T-adj showed the best performance over the low-latitude Mishui Basin. The two gauge-adjusted products demonstrate potential in water resource management. However, the accuracy of two real-time satellite precipitation products demonstrates large variability in the two validation basins. The C-rt reaches a similar accuracy level with the gauge-adjusted satellite precipitation products in the high-latitude Laoha River Basin, and T-rt performs well in the low-latitude Mishui Basin. The study also reveals that all satellite precipitation products obviously overestimate light rain amounts and events over Laoha River Basin, whereas they underestimate the amount and events over Mishui Basin. The findings of the precision characteristics associated with the latest TMPA and CMORPH precipitation products at different basins will offer satellite precipitation users an enhanced understanding of the applicability of the latest TMPA and CMORPH for water resource management, hydrologic process simulation, and hydrometeorological disaster prediction in other similar regions in China. The findings will also be useful for IMERG algorithm development and update in GPM-era.

中国大陆TMPA降水产品气候态的评估

利用逐日全国降水分析产品,对2012年12月下旬发布的最新版本的TRMM等多源卫星降水估算产品(TMPA)进行评估,评估时间从2008年9月到2012年8月。从评估结果来看,研究产品3B42V7产品与CPAP产品具有高的相关性,两者的相关系数达到了0.94,相对误差在—0.11%左右,标准偏差约为0.53 mm·d^(-1)。实时产品3B42RT产品与CPAP产品的相关性相对较差,相关系数为0.75,相对误差也上升到了39.3%,标准偏差为1.25 mm·d^(-1)。3B42RT产品在我国西部高估了降水,全年的相对误差为116.60%(春夏秋冬四季分别为104.52%、105.73%、117.64%和326.60%);3B42V7产品的相对误差仅为0.82%(春夏秋冬四季分别为2.25%、1.24%、—5.27%和—24.64%)。

TRMM多卫星降水数据在黑河流域的验证与应用

利用黑河流域9个气象台站降水数据,在不同时间尺度和空间分布上分析了2008-2011年TRMM多卫星降水数据(TMPA 3B43)在黑河流域的适用性.结果表明:用TMPA估测的年降水量在黑河流域平均高估27.3%,对上游降水量大的山区估测相对好于降水稀少的黑河下游地区;TMPA与气象站降水量的拟合优度夏季(R2=0.851)高于冬季(R2=0.332);TMPA可以较好反映各测站降水量年变化、月变化趋势,用TMPA估测的黑河流域平均年降水量变化趋势为30mm.(10a)-1.黑河流域年降水量体现出随海拔高度的递增规律(11.1mm.(100m)-1)、从东向西降水量逐渐减少的分布以及最大降水高度带出现在上游偏东地区(海拔2 800～4 900m).

分析TRMM卫星降水在径流模拟中的输入不确定性

具有较高时空分辨率的卫星降水估计(satellite precipitation estimate,SPE)越来越多地被应用于水文模拟.但是由于包含误差,SPE在水文应用中会带来输入不确定性,相关问题尚未研究清楚.本研究旨在量化两种降水输入:卫星降水产品(热带降水观测任务tropical rainfall measurement mission,TRMM)和相应的站点降水,分别驱动两个水文模型(集总式Ge′nie rural(GR)模型和分布式coupled routing and excess storage(CREST)模型,进行降雨-径流过程模拟时的多源不确定性.使用方差分解法对多源不确定性组分进行划分.为验证所提框架的有效性,选择赣江流域外洲水文站的径流进行模拟.结果表明:卫星降水和站点降水驱动下CREST模拟所得总不确定性,均低于对应情况下GR模拟所得结果;且在两种降水产品和两个水文模型结合的四种情景中,卫星降水驱动CREST模型模拟所得输入不确定性最低.上述结果表明,分布式CREST模型比集总式GR模型能更好地利用TRMM卫星降水的空间分布信息.