基于GIMMS、VGT和MODIS的中国东部植被指数对比分析

GIMMS NDVI、VGT NDVI和MODIS NDVI/EVI是目前在植被变化有关研究中经常使用的植被遥感数据,它们之间的差异也得到了广泛关注。然而,在分析这些数据之间的差异时,较少有研究注意到植被本身固有的季节循环可能夸大了各数据间的相关关系。应用2000~2006年GIMMS NDVI、VGT NDVI、MODIS NDVI/EVI等不同植被遥感数据,对比了基于这些数据集的中国东部植被年际变化的差异,探讨了植被季节循环对不同遥感数据之间相关性的影响。结果表明:由不同遥感数据提取的植被年际变化特征具有明显的一致性,然而,植被本身固有的季节循环特征掩盖了不同数据集的差异。季节循环去除前,各数据集之间具有显著的相关性；季节循环去除后,各数据集的相关性明显降低,但不同数据集在北部区域依然具有较好的一致性,其差异主要出现在南部区域,差异最明显的是GIMMS与MODIS数据,二者在淮河以南的区域几乎不存在显著相关。

Comparison of GIMMS,VGT and MODIS Vegetation Index Datasets in Eastern China

Remote sensing data sets from GIMMS NDVI,VGT NDVI and MODIS NDVI/EVI have been widely used in the studies related to vegetation change.Many previous studies have evaluated the consistency among these different data sets.However,less attention has been paid to study of the influence of seasonal cycle of vegetation,which probably amplifies the relationships among different data sets.Interannual variability of vegetation and the influence of the seasonality of vegetation on the consistency of different remotely sensed datasets had been investigated using GIMMS NDVI,VGT NDVI and MODIS NDVI/EVI products in eastern China from the period 2000 to 2006.The results indicate that all of these datasets show similar trends of the interannual variability of vegetation,whereas,the seasonality of the vegetation data overshadows the difference of different remote sensing data sources.The vegetation indices derived from GIMMS,VGT and MODIS show significant correlation before removing the seasonality,while the relationships among them decrease obviously after removing the seasonality.In general,the consistency of GIMMS,VGT and MODIS still remains in the northern part of eastern China.The differences among them mainly occur in the southern part.In particular,the most rapid decrease of correlation occurs between GIMMS and MODIS.The correlation between them has not been observed in large parts of the region located south of the Huai River.