Name:land_sea_maskAbbreviation:lsmUnit:Proportion
DefinitionThe land-sea mask is a field that contains, for every grid point, the proportion of land in the grid box. The values are between 0 (sea) and 1 (land).
Validityinstantaneous
CommentArchived for control forecast, only.

Please note the typo in the GRIB2 manual: 0=land and 1=sea. The ET-DRC agreed that this is a typo and the correct usage is: 1 indicates land and 0 indicates sea.
GRIB 2
Discipline= 2  
Parameter Category= 0  
Parameter Number= 0  
Type of first fixed surface= 1Type of second fixed surface= All 1's
Scale factor of first fixed surface= All 1'sScale factor of second fixed surface= All 1's
Scaled value of first fixed surface= All 1'sScaled value of second fixed surface= All 1's