Determination of cloud coverage over Denmark using Landsat MSS/TM and NOAA-AVHRR
Abstract:The average cloud coverage over Danish waters was calculated for the period 1975-1995 using 5487 Landsat MSS/TM images and 1571 NOAAAVHRR images. In the case of MSS/TM images, the classifications of cloud coverage between 0 and 9 (0 = no clouds, 9 = 100% cloud covered) determined by the ground station operator at Kiruna or Fucino, were used to determine average cloud cover on a monthly and yearly basis for 12 selected frames. The MSS/TM images showed an average yearly cloud coverage of 67.5%, which is close to the 66% calculated from meteorological in situ observations (standard normals 1961-1990). In the case of NOAA-AVHRR, an automatic digital classification of cloud covered pixels (0-99%) was used, and resulted in an average yearly coverage of 77.1%. The accuracy of the Landsat MSS/TM cloud coverage estimations was examined using visual inspections of a number of photo-quality quicklooks, while the accuracy of the NOAA-AVHRR cloud coverage percentages was examined using an advanced supervised multi-spectral classification on a number of scenes.
Document Type: Research Article
Affiliations: DHI-Water & Environment, Agern Allé 11, DK-2970 Horsholm, Denmark
Publication date: 2000-11-20