Operational monitoring of the European alps using NOAA-AVHRR : imagery for analysis of the multi-year vegetation index (NDVI)

[摘要] It could be shown that the normalised difference Vegetation index (NDVI) can be automatically processedfor mountainous terrain characterised by steep slopesand high cloud coverage throughout the year. Thequality of the data can be improved if the variables forthe atmospheric correction (water vapor, ozone andpressure) are taken from a finer grid resolution and ifthe actual aerosol optical depth is used. However, evenunder these improved concitions, the magnitude of theNDVI would differ but the behavior and shape of thegraphs in general would remain. Die upward trend ofthe winter NDVI in the years 1995–1998 is significantfor the altitudinal levels 1001–1500 m and 501–1000 m.To be able to find out more about the snow coveredareas at these heights, reference was made to the airtemperatures of Zürich, Engelberg and Santis. Thus,we were able to show that the increase of NDVI atlower elevations during the wintertime was linked todecreasing snow covered areas. In elevations above2000 m, a slight increase in the summer NDVI couldbe detected but the linear trend is not significant. Anexplanation for this could not be given due to missingmeta-data, such as the extent of the snow covered area.In conclusion, it may be said that there is a good correlationbetween the air temperature and the NDVI, butthat the quality of the precipitation database does notallow for a correlation to be made between precipitation and the NDVI.

[学科分类] 自然科学（综合）