利用NOAA-AVHRR数据进行积雪监测与制图的方法研究

SNOW COVER MONITORING AND MAPPING USINS NOAA-AVHRR DATA

本文在总结分析国内外现有方法的基础上，并根据大量的实验研究，介绍了利用NOAA－AVHRR遥感数据进行积雪监测和流域雪盖制图的方法。文章侧重介绍了AVHRR数据在积雪制图应用中的数据处理方法。也较为详细地介绍了利用遥感数据和地形数据的复合进行积雪信息提取的方法。研究表明：在地形相对复杂的地区使用AVHRR数据进行积雪监测和制图，采用监督分类的方法可获得较为理想的分类结果。利用GIS的空间分析方法，实现遥感和地形数据的复合分是积雪遥感制图高效和实用的方法之一。

Data from the NOAA-AVHRR system are widely used today for snow cover monitoringand mapping in the world.In regions where snow cover is a significant hydrologic variale,the satellite areal extent of snow cover data can be used when issuing spring flood outlooks,watersupply outlooks,river and flood forecasts,and reservoir inflow forecasts.In recent years,the discussion of climate change attracted also the attention of scientists because snow plays an important role in the hydrologic cycle and in a feedback mechanism to the atmosphere.TheNOAA satellites are proved to be the useful system for monitoring such phenomena over largein NOAA-AVEHRR data,special attention is given to the digital image processing techniques,including data selection,data preprocessing,geometric corrections,projection transformaton,classification, and classfifcation results analysis.Furthermore,the integration of image processing and GIS techniques for integrating satellite and geographical data and extracting snow coverinformation are also preented in this paper.It has been shown that AVERR data can be usedfor monitoring and mapping snow successfully, even under the complicated topograhical conditions.For the classification,several calassifier are available, only Minimun Distance and Mahalanobis Distance classifers show satisfactory results,the Maximum Likelihood classfifer canreach good results of the training area is well selected In operational snow cover mapping,it isnot possible to compare the classfifcation results with actual field measuremjents,The accuracyhas to be checked by comparing the original staellite image wiht the classification results.In addition,it is shown that the use of spatial analysis techniques of GIS is an effective way for monitoring and mapping snow cover.By combining the AVHRR and topograhical data,it not onlyallows the geocoding of the AVHRR data,but also permits the accurate mapping and analysisof snow with the topographical information in the study area.