辽宁地区不同地表覆盖类型EVI和NDVI特征

目的基于MODIS数据，研究辽宁地区4种不同地表覆盖类型下两种植被指数EVI和NDVI随时间的变化规律，为辽宁地区地表覆盖类型动态监测提供研究途径．方法利用2012年MODIS数据，在辽宁地区选择16个感兴趣区，分析林地、耕地、水体、城区4种地表覆盖类型下EVI和NDVI的特征．结果在林地覆盖区，林木在返青期和生长旺盛期NDVI和EVI均呈现钟形曲线，NDVI出现饱和现象，EVI能克服了这一缺点；在耕地覆盖区，农作物在生长期NDVI和EVI均呈现倒V形曲线；在水体覆盖区和城区，NDVI和EW除在夏季略有升高外，全年变化较小，NDVI受噪声影响较大，而EVI克服了这一缺点．结论NDV!和EVI的数字特征表明，在耕地覆盖区EVI能够很好地监测林木长势，在耕地覆盖区NDVI和EVI都能很好地监测农作物的长势，在水体覆盖区和城区EVI能够更好地监测植被的长势．

Analysis of EVI and NDVI Characteristics in Different Land Cover Types in Liaoning Province

Basing on MODIS data, both EVI and NDVI variations of four types of land cover in Liaoning province were studied in time series. The result can offer the method of monitoring land cover types. The 16 regions of interest in Liaoning province from four kinds of land cover, including woodland, plowland, water and urban were selected. Their characteristics of EVI and NDVI were analyzed by the data statistics method, and the data were from 2012 MODIS data. In the woodland coverage areas ,the shape of their NDVI and EVI in time series looked like a bell-shaped curve in the period of forests turning green and growing,NDVI was prone to become saturated, and could not show the growth process of trees while EVI could better do that. In the plowland coverage area, the shape of their NDVI and EVI in time series looked like an inverted V-shaped curve in the period of crops growing season. In the water coverage areas and urban, the values of their NDVI and EVI were slightly higher in the summer than other seasons, and the annual variation range of their NDVI and EVI was small. In the plowland coverage areas, both NDVI and EVI could well show the process of veg- etation growth. In the water coverage areas and urban ,NDVI sensitively influenced by noise, while EVI could overcome this shortcoming. The curves shapes of NDV1 and EVI under different land cover types are of greatsignificance for vegetation classification and extraction in Liaoning province. The figures characteristics of NDVI and EVI indicate that EVI can well monitor the growth of forest in the woodland coverage areas, both NDVI and EVI can monitor the growth of crops in the plowland coverage area, and EVI can well monitor the ~rowth of vegetation in the water coverage areas and urban.