2000—2013年5—10月TRMM测雨产品3B42RT在浙江地区的评估检验

利用2000—2013年5—10月浙江省70个常规站逐小时降水观测资料来检验同期TRMM卫星3B42RT降水产品,尤其针对台风降水进行了评估。对比分析得出,2000—2013年5—10月3B42RT资料与台站观测资料在3 h、6 h、12 h和24 h 4个时间尺度上降水总量接近,两组数据呈显著正相关,相关系数随时间尺度的增大而加强,相关系数大值区位于浙江西部地区;无论是5—10月还是台风降水期间,3B42RT测雨资料的日变化特征与台站观测资料均较为一致,3B42RT能够准确抓到峰值出现的时间;台风期间3B42RT数据表征的全省降水普遍偏低,但与台站观测数据的相关性明显好于5—10月全时段,且相关系数大值区位于浙江东部沿海地区,台风前后时刻的3B42RT逐3 h降水量差值序列与台站观测降水量差值序列呈显著正相关,两组资料表征的降水量变化随时间的演变趋势较为一致。另外,选取2004年0414号台风"云娜"进行相关分析和基于目标诊断技术检验,发现3B42RT资料对降水的结构预报和实况相似度较高。

Evaluation of high-resolution satellite precipitation products with surface rain gauge observations from Laohahe Basin in northern China

Three high-resolution satellite precipitation products, the Tropical Rainfall Measuring Mission （TRMM） standard precipitation products 3B42V6 and 3B42RT and the Climate Precipitation Center＇s （CPC） morphing technique precipitation product （CMORPH）, were evaluated against surface rain gauge observations from the Laohahe Basin in northern China. Widely used statistical validation indices and categorical statistics were adopted. The evaluations were performed at multiple time scales, ranging from daily to yearly, for the years from 2003 to 2008. The results show that all three satellite precipitation products perform very well in detecting the occurrence of precipitation events, but there are some different biases in the amount of precipitation. 3B42V6, which has a bias of 21%, fits best with the surface rain gauge observations at both daily and monthly scales, while the biases of 3B42RT and CMORPH, with values of 81% and 67%, respectively, are much higher than a normal receivable threshold. The quality of the satellite precipitation products also shows monthly and yearly variation： 3B42RT has a large positive bias in the cold season from September to April, while CMORPH has a large positive bias in the warm season from May to August, and they all attained their best values in 2006 （with 10%, 50%, and -5% biases for 3B42V6, 3B42RT, and CMORPH, respectively）. Our evaluation shows that, for the Laohahe Basin, 3B42V6 has the best correspondence with the surface observations, and CMORPH performs much better than 3B42RT. The large errors of 3B42RT and CMORPH remind us of the need for new improvements to satellite precipitation retrieval algorithms or feasible bias adjusting methods.

多种卫星降水产品对中国极端降雨反演效果评估

利用7种极端降雨指标分析评估TRMM 3B42、TRMM3B42RT及CMORPH这3种主要的卫星降水产品在中国地区的表现。为全面、科学地评估这些产品,采用不同的时间尺度、空间尺度以及评价指标来作检验,结果表明:1)总体上3B42的表现比3B42RT和CMORPH要好,3B42RT倾向于高估,而CMORPH则倾向于低估;2)在对极端降雨量的表现中,3种产品对喜马拉雅山脉地区都存在着高估现象,并在春季的表现最好;3)在对极端降雨强度的表现中,3种卫星降水产品对PRCPTOT的表现更好,尤其在全中国和西部;4)在对周期的表现上,3种产品对海拔较高的地方均有着显著地高估,另外,CMORPH对海拔较低的地方同样存在着高估的现象,3种产品对CWD的表现更好。在中国极端降雨的探测上,3B42要优于3B42RT和CMORPH,但是它们对海拔较高的地方均存在一定程度的高估,因此在这些地方使用时要谨慎。