MODIS光谱指数在中国西南干旱监测中的应用

利用标准化降雨指数SPI比较了基于MODIS反射率数据提取的8种光谱指数(NDVI、NDWI、VARI、EVI、NDIIB6、NDIIB7、D1640和SR)对中国西南四省市(四川、重庆、云南和贵州)2000年—2012年典型干旱事件的反映。研究结果表明:(1)SPI指数能直接反映监测站点附近的干旱情况,其中3个月和6个月尺度的SPI(SPI3和SPI6)对2006年和2009年—2010年该区的特大干旱事件的监测效果较好;(2)除了D1640外,其余7种光谱指数的距平值与3个月尺度的SPI3都具有显著的相关性,其中NDIIB7、NDIIB6和VARI与SPI3的相关性较高(R0.3),在一定程度上可以表征中国西南地区的干旱状况;(3)MODIS NDIIB7距平值与3个月尺度的SPI3相关性最高(R=0.35),本文以其为例,再现了云贵高原2009年—2010年特大持续干旱事件的时空演变过程。

Responses of MODIS spectral indices to typical drought events from 2000 to 2012 in southwest China

This study uses the Standard Precipitation Index (SPI) to compare the responses of eight MODIS-based spectral indices to typical drought events, including NDVI, NDWI, VARI, EVI, NDIIB6, NDIIB7, D1640, and SR, from 2000 to 2012 in southwest China, Containing the provinces of Sichuan, Chongqing, Yunnan, and Guizhou. The results show that: (1) The SPI index derived from precipitation data could reflect the drought conditions around the station, and the three-month and six-month SPIs (SPI3/6) perform better than the other time-scale SPIs; (2) Anomalies of all eight MODIS-based spectral indices, except for D1640, show significant correlation with SPI3 at a confidence level of 95% and can thus be used to reveal the drought conditions in southwest China to some degree, whereas anomalies of NDIIB7, VARI, EVI, and NDIIB6 have higher r values with SPI3 (r>0.3) than others; (3)The anomalies of NDIIB7 have the highest r value with SPI3 and are used to analyze the spatiotemporal development and recovery of the long-term extreme drought event that occurred in Yungui Plateau during 2009 to 2010.