GRIB-API definition
Name | Volumetric soil moisture | Abbreviation | vsw | Unit | m3 m-3 | paramId: |
TBD
UERRA details
Definition | Volumetric soil moisture of a soil layer. |
Validity | instantaneous |
Comment |
Averaged volumetric soil moisture between given levelsSea 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 |
---|
Discipline | 2 | land surface products |
Parameter category | 0 | vegetation/biomass |
Parameter number | 25 | volumetric soil moisture |
Level |
---|
Type of first fixed surface |
layerlevel** |
Scale factor of first fixed surface |
all bits to 1 | missing0 | |
Scaled value of first fixed surface |
soil layer number | 0/1/2/3/.../X-1 | n-1 for the nth soil layer |
Type of second fixed surface |
all bits to 1 | missing151 | soil level* |
Scale factor of second fixed surface |
all bits to 1 | missing0 | |
Scaled value of second fixed surface |
all bits to 1 | missing1/2/3/.../X | n for the nth soil layer |
**newly approved level type (WMO release in May 2016)