TMPA卫星遥感降水数据产品在中国大陆的干旱效用评估

为评估基于卫星遥感的高时空分辨率降水数据产品在干旱研究中的应用能力,该研究以标准化降水指数(standardized precipitation index,SPI)和标准化降水蒸散指数(standardized precipitation evapotranspiration index,SPEI)为例,以站点实测降水数据产品作为参考,评估了热带降水测量计划——多卫星降水分析(tropical rainfall measurement mission(TRMM)multi-satellite precipitation analysis,TMPA)3B42V7产品在中国大陆范围内1998-2015年间的干旱效用.结果表明:1)基于3B42V7计算的干旱指数总体上具有较高的精度,在中国东部大部分地区与基于降水实测数据的干旱指数相关系数均在0.8以上;2)基于西南和华北2个典型干旱发生地区的干旱时空变异评估结果表明,3B42V7能较为准确地反映干旱事件的发展过程和强度并能较好地捕捉干旱事件的空间模式,并且在大多数情况下单纯基于3B42V7数据计算的SPI指数即可满足干旱监测的要求;3)干旱事件识别能力评估结果表明,3B42V7产品能够较准确地识别和定位1998年以来的大范围干旱.TMPA产品能从时间和空间上刻画出中国大陆干旱的演变规律,适用于大尺度气象干旱的监测与评估.

Evaluation of drought utility assessment of TMPA satellite-remote-sensing-based precipitation product in mainland China

Satellite-remote-sensing-based precipitation analysis products with high spatiotemporal resolution provided a new data source for the studies of drought. The aim of this study is to evaluate the drought assessment utility of the TMPA (tropical rainfall measurement mission (TRMM) multi-satellite precipitation analysis) 3B42V7 post-real-time satellite-based precipitation product in mainland China. We evaluate the accuracy of 3B42V7-based drought indices, the capability of the 3B42V7 product to reveal the spatiotemporal variation of drought, and the capability to identify the drought events in 1998-2015 based on 2 widely used meteorological drought indices, i.e. SPI (standardized precipitation index) and SPEI (standardized precipitation evapotranspiration index), with CGDPA (China gauge-based daily precipitation analysis) as the evaluation reference, which is an interpolated gauge-based precipitation dataset. The potential evapotranspiration (PET) used to calculate the SPEI is calculated by meteorological data of 818 meteorological stations and 129 radiation stations among the mainland China and interpolated with the Kriging method. Considering that the sensitivity of the drought indices to the length of base period might affect the evaluation, the CGDPA-based drought indices are calculated in the periods with 2 lengths: the period of 1998-2015 (18 years, CGDPA18a), the same period of the 3B42V7 observation history, and a longer period of 1960-2015 (56 years, CGDPA56a). The results show that: 1) SPI and SPEI based on 3B42V7 product generally show acceptable accuracy over mainland China except the mid-west and south Tibetan Plateau, with high correlation coefficients over 0.8 in most of the east part of mainland China with those of both CGDPA18a and CGDPA56a. 2) Evaluation of the spatial and temporal variation of drought focusing on southwestern China (SWC) and northern China (NC), the 2 typical drought affected regions in China, shows that the time series of the area-averaged drought indices, and the spatial pattern of drought indices derived from 3B42V7 have high consistency with both the CGDPA18a and the CGDPA56a, indicating that 3B42V7 can reflect the evolution process and intensity of drought events, capture the spatial pattern of drought events, and reveal the spatiotemporal evolution of drought reasonably. In addition, the 3B42V7-based SPI is generally comparable to the SPEI in many cases, indicating that the SPI calculated only from the 3B42V7 data has already met the requirement of drought monitoring in the non-arid region of mainland China. 3B42V7 can generally accurately catch the moving path of the centroid of drought from September 2010 to October 2011 in eastern China, which indicates that the 3B42V7 can reasonably reveal the spatiotemporal variation of drought. 3) 3B42V7 product is capable of recognizing the large-scale drought events that took place during 1998-2015 and finding out their spatio and temporal positions truly and reasonably. Although some differences of the droughts affected area and severity of the drought events were found between those calculated from 3B42V7 data and those of CGDPA data, 3B42V7 product can reflect the temporal and spatial evolution of droughts in mainland China. In conclusion, the 3B42V7 product is suitable for monitoring and evaluation of meteorological drought at large scale.