基于MODIS/NDVI与EVI的皖江流域植被覆盖比较分析

利用多时相的TERRA/MODIS影像资料比较了皖江流域NDVI和EVI的时空分布特征，并分析了空间分辨率和大气校正对NDVI和EVI的影响。结果表明：MODIS/NDVI与MODIS/EVI所反映的植被覆盖状况基本一致，但5月份较8月份NDVI和EVI的空间分布差异明显，且在植被生长旺盛时期，EVI比NDVI更能反映植被覆盖状况。在相同的空间分辨率下（250 m、500 m、1 000 m），EVI比NDVI能更好的反映植被覆盖的空间差异性，随着空间分辨率的降低，这两种指数反映植被覆盖的差异性在减小。大气校正对NDVI和EVI的影响不同，大气校正前NDVI值小于EVI值，大气校正后NDVI值普遍大于EVI值，但大气校正对NDVI的影响不大，对EVI的影响明显

COMPARATIVE ANALYSIS OF VEGETATION COVERAGE ALONG THE YANGTZE RIVER IN ANHUI PROVINCE BASED ON MODIS/NDVI AND EVI

The temporal and spatial variation characteristics of NDVI and EVI along the Yangtze River in Anhui province are compared by using multi-temporal TERRA/MODIS remote sensing images,and the spatial resolution and the atmospheric correction influences on NDVI and EVI are also analyzed in this paper.The results show that the vegetation coverage conditions reflected by MODIS / NDVI and MODIS / EVI are basically the same.The spatial distribution in May shows more obvious differences than that in August,and in vigorous growth period,EVI can reflect the vegetation coverage conditions better than NDVI.In the same spatial resolution(250 m,500 m,1000 m),EVI can reflect the spatial differences of the vegetation coverage much better than NDVI.With the reducing of the spatial resolution,the differences of the vegetation coverage reflected by the two kinds of indexes also decrease.Atmospheric correction has different influences on NDVI and EVI.The values of NDVI are lower than the EVI values before the atmospheric correction,while after the atmospheric correction,the values of NDVI are generally higher than the EVI values.The atmospheric correction has less effect on the NDVI but more significant effect on EVI.