This site has moved to www.usgs.gov/landsat
Please visit the new site and update any bookmarks you have. 
 

Question:

What is the difference between the Scene Cloud Cover and the Land Cloud Cover Scores?

Answer:

Scene Cloud Cover is determined by the C Function of Mask (CFMask) algorithm. This algorithm provides a full-image “Scene Cloud Cover” estimation of the percentage of cloud cover calculated over an entire Landsat scene.  

Land Cloud Cover is determined by calculating the percentage of clouds over only the land pixels in a scene. A mask used to discriminate land from water is derived from the NOAA World Vector Shoreline Dataset.

Both cloud cover percentages are listed in the EarthExplorer metadata, as well as in the Landsat Collection 1 Level-1 metadata (MTL.txt) file. 

For example, if only half of image is cloud covered, while all of the land in the image is cloud covered:

CLOUD_COVER = 50.00
CLOUD_COVER_LAND = 100.00
Values are percentages (range is 0.00-100.00)