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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(250m、500m、1 000m),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。
The temporal and spatial distribution characteristics of NDVI and EVI in Wanjiang River Basin were compared using multi-temporal TERRA / MODIS image data. The spatial resolution and the effect of atmospheric correction on NDVI and EVI were analyzed. The results showed that the vegetation coverage reflected by MODIS / NDVI and MODIS / EVI was basically the same, but the spatial distribution of NDVI and EVI in May was significantly different from that in August, and EVI reflected the vegetation coverage better than NDVI in vegetation growth . At the same spatial resolution (250m, 500m, 1000m), EVI can better reflect the spatial variability of vegetation coverage than NDVI. With the reduction of spatial resolution, these two indices reflect the difference of vegetation coverage Decrease Atmospheric correction has different effects on NDVI and EVI. NDVI before atmospheric correction is less than EVI. After atmospheric correction, NDVI values are generally larger than EVI values, but atmospheric correction has little effect on NDVI and has a significant impact on EVI.