中文摘要：

采用最大值合成法，以MODIS 250m分辨率图像为基础，提取湖南省2005年逐月植被指数值．通过月植被指数对比分析，将湖南省分为6个区描述其空间分布特征．利用5个分布均匀的气象站观测的月降水量和月平均气温数据，分析了湖南省植被指数的时相变化特征．结果表明：湖南省MODIS植被指数空间分布与植被覆盖率呈正相关，且具有一定的地域性；MODIS植被指数随季节变化，其月平均植被指数曲线形似开口向下的二次抛物线，最大值出现在7月份；MODIS月平均EVI值小于MODIS月平均NDVI值；植被指数的季节变化受温度影响较大，并且随着纬度的降低，温度对植被指数的影响力下降；MODIS EVI的变化规律比MODIS NDVI更加明显，其二次曲线更为光滑，月平均值由低逐渐上升到最大值，再逐渐降低，而后者的曲线在最大值两侧有细微波动现象．

英文摘要：

Based on MODIS images and by using the algorithm of maximum value composite （MVC）, the monthly vegetation indices （VIs） in 2005 in Hunan Province were obtained. Through the analysis of the MODIS VIs, Hunan Province was divided into six districts to describe the spatial distribution of the VIs, and by using the monthly mean temperature and rainfall data collected from 5 climatic monitoring stations in this province, the temporal variation of the VIs was analyzed. The results showed that the spatial distribution of MODIS VIs was positively correlated with vegetation cover, and appeared regional characteristics. The MODIS VIs varied with season, and the curves of their monthly mean values were downwards opening quadratic parabolas, with the maximum appeared in July. The value of MODIS EVI was smaller than that of MODIS NDVI. MODIS VI was mainly affected by monthly mean temperature, but this effect was decreased with decreasing latitude. The variation pattern of MODIS EVI was more apparent than that of MODIS NDVI, i. e. , the quadratic parabola of MODIS EVI was smoother, going gradually from minimum to maximum and then going down, while that of MODIS NDVI had tiny fluctuations on both sides of the maximum point.