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 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 |
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Discipline | 2 | land surface products |
Parameter category | 0 | vegetation/biomass |
Parameter number | 25 | volumetric soil moisture |
(all but Meteo-France) |
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Type of first fixed surface |
layerlevel** |
Scale factor of first fixed surface | 0 | |
Scaled value of first fixed surface |
soil layer number | | Type of second fixed surface | all bits to 1 | missing |
Scale factor of second fixed surface | all bits to 1 | missing |
Scaled value of second fixed surface | all bits to 1 | missing |
Level (Meteo-France only) |
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Type of first fixed surface | 1 | depth below land surface (m) |
Scale factor of first fixed surface | 0 | |
0/1/2/3/.../X-1 | n-1 for the nth soil layer |
Scaled value of first fixed surface | 0 | |
Type of second fixed surface |
106 or 167***
| "depth below land surface (m)" or "bottom of root zone"***151 | soil level* |
Scale factor of second fixed surface |
1 or all bits to 1*** | (cm) or missing***0 | |
Scaled value of second fixed surface |
value in cm or all bits to 1*** | 1 or missing*** | 1/2/3/.../X | n for the nth soil layer |
**newly approved level type (WMO release in May 2016*** valid for the 3rd Meteo-France layer (from surface to the bottom of root zone)