Landsat Missions
Question:
How is the percentage of cloud cover calculated?
Answer:
The Landsat 7 Processing System determines the percentage of cloud cover by applying the Automatic Cloud Cover Assessment (ACCA) algorithm, which is based on the premise that clouds are colder than Earth surface features. The algorithm works well in most cases, but occasionally, temperature inversions occur and invalid cloud cover assessments may result. While there are also intermittent problems with the ACCA detection of popcorn clouds and haze, the ACCA algorithm maintains a higher degree of overall accuracy than the previous methods employed for past Landsat processing systems.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://landsat.usgs.gov
Page Contact Information: landsat@usgs.gov
Page Last Modified: November 24, 2009
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