基于MODIS和NOAA/AVHRR的荒漠化遥感监测方法

土地荒漠化是中国西部最严重的生态环境问题，荒漠化遥感监测技术是掌握荒漠化发展趋势的重要手段。基于空间分辨率为1 km的NOAA/AVHRR和MODIS遥感数据，首先依据湿润指数法确定了荒漠化范围和气候分区。然后选取出了可以反映不同荒漠化特征，并且能够通过中低分辨率的NOAA/AVHRR和MODIS遥感影像反演出来的5个荒漠化遥感监测指标，通过精度评价分析，确定了最佳指标组合。由于MODIS和NOAA/AVHRR数据的影像特征存在较大差异，针对每一气候分区， 建立了分别适用于MODIS和NOAA/AVHRR数据的两套遥感指标分类体系。通过不同分类方法的比较，确定了最佳分类方法－决策树分类法。通过对中国1995年和2001年的荒漠化动态变化状况进行了分析，结果表明，本文提出的荒漠化遥感监测方法，不仅能够成功地进行大尺度的荒漠化遥感监测，而且能够取得较好的监测效果。

Method for remote sensing monitoring of desertification based on MODIS and NOAA/AVHRR data

Desertification is one of the most serious ecological and environmental problems in the west of China. Understanding the distribution and development trend of desertification provides researchers important scientific basis for desertification control and rehabilitation. In this paper the authors proposed a method suitable for large-scale desertification monitoring using remote sensing techniques. First, five desertification indexes(MSAVI, FVC, Albedo, LST and TVDI) suitable for large-scale desertification monitoring using remote sensing technique were selected. In terms of the desertification climate types, the potential extent of desertification in China was respectively divided into four categories: dry sub-humid areas, semi-arid areas, arid areas, high and cold areas. Second, different desertification index systems were built for each area. Then based on analysis and comparison of current retrieval algorithms, the authors utilized a suitable algorithm on large scale to retrieve five desertification indexes with ten-day NOAA/AVHRR data set in 1995 and 16-day MODIS data set in 2001 in China. By assessing the classification accuracies of three types of classifiers, the authors selected decision tree classifier for desertification monitoring. Supported by desertification index system and the database of desertification indexes, the desertification status in China in 1995 and 2001 was classified by decision tree classifier, and analysis of desertification changes from 1995 to 2001 was also completed. Statistical result showed that the speed of desertification development was faster than that of rehabilitation, there was a trend of development as a whole and improvement locally in desertificated areas in China. The desertification monitoring results confirmed the practicability of the method founded in this paper for desertification monitoring.