说明：  读取NDVI文件 基于月数据年平均合成处理 统计年均NDVI并绘制曲线 计算年际变化率 将结果保存为ENVI标准文件
(Read the NDVI file Composite processing based on monthly data and annual average The average annual NDVI was calculated and the curves were plotted Calculate the interannual rate of change Save the results as an ENVI standard file)