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GRIB-API definition

NameVolumetric soil moistureAbbreviationvswUnitm3 m-3paramId:
TBD
260199

 

UERRA details

DefinitionVolumetric soil moisture of a soil layer.
Validityinstantaneous
Comment
Averaged volumetric soil moisture between given levels

Sea points should be set as missing values (encoded as bitmap). Soil layers must always start from 1 (0 soil level is the surface by default which is not encoded).

To interpret soil moisture and to compare different models the Soil Wetness Index (SWI) is used:
SWI = (soil_moisture - wilting_point) / (field_capacity - wilting_point).

Field capacity corresponds to the maximum value that the model can sustain without precipitation for more than a few hours. The vegetated fraction of the soil evaporates at the maximum rate for soil moisture larger than field capacity and stops evaporating below the permanent wilting point, with a continuous variation between the two extremes.
All Partners are asked to provide the wilting point and the field capacity for each grid point.

 

WMO GRIB2 definition

Parameter
Discipline2land surface products
Parameter category0vegetation/biomass
Parameter number25volumetric soil moisture
Level
Type of first fixed surface
 
151soil
layer
level**
Scale factor of first fixed surface
all bits to 1missing
0 
Scaled value of first fixed surface
soil layer number 
0/1/2/3/.../X-1n-1 for the nth soil layer
Type of second fixed surface
all bits to 1missing
151soil level*
Scale factor of second fixed surface
all bits to 1missing
0 
Scaled value of second fixed surface
all bits to 1missing
1/2/3/.../Xn for the nth soil layer

**newly approved level type (WMO release in May 2016)