GRIB-API definition
Name | Skin temperature | Abbreviation | skt | Unit | K | paramId | 235 |
Definition | Temperature of of an infinitesimally thin surface layer of land or water surface at radiative equilibrium. |
Validity | instantaneous |
Comment |
GRIB2 definition
Parameter | ||
---|---|---|
Discipline | 0 | meteorological products |
Parameter Category | 0 | temperature |
Parameter Number | 17 | skin temperature |
Level | ||
---|---|---|
Type of first fixed surface | 1 | ground or water surface |
Scale factor of first fixed surface | all bits to 1 | missing |
Scaled value of first fixed surface | all bits to 1 | missing |
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 |
4 Comments
Richard Mladek
Further specification needed.
Per Unden
Temperature of an infinitesimally thin surface layer of land or water corresponding to the kinetic energy of the matter.
Gianpaolo Balsamo
The skin temperature SKT is a temperature in radiative equilibrium and is globally defined (land and water point) but it is instantaneous and has no memory. This is interesting because it shall be the temperature comparable to a satellite skin temperature.
An ECMWF-IFS alternative that has memory and it is an actual prognostic is the STL1 grib code, which is the top soil temperature (representative of 0 to 7 cm depth). STL1 over water is equal to SSTK and over ice is equal to ISTL1 (the top layer ice temperature), therefore it is also globally defined. However it is just used in GRIB1 and not a WMO defined GRIB2.
An alternative would be to consult S2S parameters, which were defined with purpose of finding common intercomparable quantities, see:
List of S2S parameters.
It is very likely that this quantity will remain model-dependent as there is a variety of modelling assumption concerning the way soil vertical discretisation and root distribution are represented in models.
Per Unden
I think we settle for Skin temperature as Surface temperature is ill defined.