DETECTION OF SNOW COVER ON THE AREA OF POLAND USING AVHRR/NOAA SATELLITE INFORMATION

摘要

During last two years in Satellite Data Receiving and Processing Centre in Krakow, the method of snow cover detection was prepared and tested. This method is based on information from visible and infrared channels of the AVHRR instrument. Detection ofthe snow cover consist of: real time receiving of daytime AVHRR transmission, selection of appropriate area in all AVHRR channels, calibration of visible and infrared channels, snow cover detection and cloud masking, transformation of classified image to map projection and insertion of the coast lines to distinguish land snow and sea ice. Most important part of this method concern separation of snow and clouds especially on images with low Sun elevation. Use of the all five AVHRR channels and correction of the Sun elevation and Sun to sensor position are necessary. For good snow detection in forest area, classified image with types of ground cover is used as mask. This image were prepared using temporal profiles of vegetation indices calculated from AVHRR data on the area of Poland. In case of partial cloudiness, composition of several classified and geometrically corrected images is available.