融合气象和遥感植被信息的综合干旱指数构建及精度评价

Construction and Precision Evaluation of Comprehensive Drought Index Based on Meteorological and Remote Sensing Vegetation Information

干旱的准确监测对于全球农业生产有着重要的现实意义,作为衡量区域干旱程度的重要工具之一,具有较高监测精度的综合指数的构建是当今干旱灾害研究的热点之一。基于Gaussian Copula函数,联合归一化植被指数(normalized difference vegetation index,NDVI)和月平均降水两种常见的干旱影响变量,构建了一种综合降水和遥感植被特征的新型综合干旱指数(meteorology-agriculture drought index,MADI)。与月尺度标准化降水指数(standardized precipitation index,SPI)和植被状态指数(vegetation condition index,VCI)的对比,以及在历史干旱事件中的检验,证实了采用MADI捕捉干旱事件的优越性。研究结果表明:(1)MADI与传统干旱指数SPI和VCI对干旱表征的一致性均较高。MADI与SPI表征一致的月份占总月份的62.24%,与VCI表征一致的月份占总月份的83.82%;(2)MADI对干旱现象的敏感性高。在MADI与SPI和VCI表征一致的月份中,60%以上的月份中MADI的绝对值较SPI和VCI更大,对干旱的表征更明确;(3)结合年鉴记载的历史干旱事件验证表明,MADI具有较高的准确性。MADI成功捕捉到2012年1月—4月以及2007年的8月—10月的两次重大干旱事件,而SPI和VCI在两次事件中的表征均存在遗漏。由此可见,MADI可以作为SPI和VCI的有益补充,为长江流域干旱灾情的准确判定提供辅助决策。

Objectives:Accurate monitoring of drought is of great practical significance for agricultural production around the world,and it is beneficial to the sustainable development of an economy.As a vital tool to measure the degree of regional drought,the construction of a comprehensive drought index with high monitoring accuracy is one of the research hotspots nowadays.Methods:We constructed a new comprehensive drought index meteorology-agriculture drought index(MADI)combined with the normalized difference vegetation index(NDVI)and monthly mean precipitation based on the Gaussian Copula function.The superiority of MADI in capturing drought events was confirmed by statistical comparison with standardized precipitation index(SPI)and vegetation condition index(VCI)at monthly scale and by testing in historical events.Results:The research result the research shows that:(1)MADI has high consistency with traditional drought indexes SPI and VCI.The months with a consistent characterization of MADI and SPI accounted for 62.24%of the total months.And the figure is 83.82%taking into account the MADI and VCI.And the months that MADI with either consistent characterization of SPI or VCI to characterize drought accounted for 97.83%of the total months.(2)MADI has high sensitive to capturing drought.In the months when MADI is consistent with SPI and VCI characterization,the absolute value of MADI is greater than that of SPI or VCI in more than 60%of the months,which means that the MADI is clearer in drought characterization.(3)MADI is more accurate in contrast to the record of historical drought events in the meteorologic yearbook.MADI successfully capture two major drought events from January to April 2012 and August to October 2007.However,the SPI and VCI fail to characterize the above events.Conclusions:Therefore,the MADI can serve as a helpful complement to SPI and VCI since it can provide an auxiliary decision for the accurate judgment of drought disasters in the Yangtze River Basin.