Introduction

The tables shown on this page summarize the list of variables requested from the providers of "Operational Products of Seasonal Forecasts", according to the invitation to tender C3S_330 (more info here). Note this list has been also later updated to reflect the evolution of those requirements.

This list includes some basic information for encoding those variables in netCDF. A more detailed information page about the encoding in netCDF will be found in the Guide to NetCDF encoding for C3S seasonal providers, which should be considered the definitive specification for the data encoding of the files to be provided.

Note that alongside the basic encoding information in netCDF, i.e. CF standard name and canonical units, the tables contain some details about GRIB encoding which was used in the previous C3S seasonal forecast datasets.

Requested variables from providers

Static Data

GRIB

netCDF

name

parameter ID

units

CF standard name

canonical units

Land-sea mask

172

(0-1)

land_area_fraction

1

Geopotential

129

m2 s-2

surface_altitude

m


Surface Fields

Sub-daily data


GRIB

netCDF

time step

name

parameter ID

units

CF standard name

canonical units

6h

2 metre temperature

167

K

air_temperature

K

6h

2 metre dewpoint temperature

168

K

dew_point_temperature

K

6h

10 metre U wind component

165

m s-1

x_wind

m s-1

6h

10 metre V wind component

166

m s-1

y_wind

m s-1

6h

Mean sea level pressure

151

Pa

air_pressure_at_sea_level

Pa

6h

Total cloud cover

164

(0-1)

cloud_area_fraction

1

6h

Soil temperature level 1

139

K

soil_temperature

K

6h

Sea surface temperature (1)

34

K

sea_surface_temperature

K

6h

Sea ice temperature (1)

500172

K

sea_ice_temperature

K

(1) GRIB data streams could contain those variables as a composite field with parameter ID=139

Daily instantaneous data


GRIB

netCDF

time step

name

parameter ID

units

CF standard name

canonical units

24h

Sea-ice cover

31

(0-1)

sea_ice_area_fraction

1

24h

Volumetric soil water layer 1 (2)

39

m3 m-3

moisture_content_of_soil_layer  (2)

kg m-2

24h

Volumetric soil water layer 2 (2)

40

m3 m-3

24h

Volumetric soil water layer 3 (2)

41

m3 m-3

24h

Volumetric soil water layer 4 (2)

42

m3 m-3

24h

Snow depth

141

m of water equivalent

lwe_thickness_of_surface_snow_amount

m

24h

Snow density

33

kg m-3

snow_density

kg m-3

24hTotal column water vapour137kg m-2atmosphere_mass_content_of_water_vaporkg m-2
24hTotal column cloud liquid water78kg m-2atmosphere_mass_content_of_cloud_liquid_waterkg m-2
24hTotal column cloud ice water79kg m-2atmosphere_mass_content_of_cloud_icekg m-2

(2) soil water content should be provided for all native model levels (so 39-42 GRIB parameter IDs just apply to ECMWF/IFS soil model)

Daily time-aggregated data (accumulations, max/min,etc)


GRIB

netCDF

time step

name

parameter ID

units

CF standard name

canonical units

24h

Maximum temperature at 2 metres in the last 24 hours

51

K

air_temperature

K

24h

Minimum temperature at 2 metres in the last 24 hours

52

K

air_temperature

K

24h

10 metre wind gust since previous post-processing

49

m s-1

wind_speed_of_gust

m s-1

24h

Large-scale precipitation (4)

142

m

lwe_thickness_of_stratiform_precipitation_amount (4)

m

24h

Convective precipitation (4)

143

m

lwe_thickness_of_convective_precipitation_amount (4)

m

24h

Total precipitation

228

m

lwe_thickness_of_precipitation_amount

m

24h

Snowfall

144

m of water equivalent

lwe_thickness_of_snowfall_amount

m

24h

Surface sensible heat flux

146

J m-2

surface_upward_sensible_heat_flux

W m-2

24h

Surface latent heat flux

147

J m-2

surface_upward_latent_heat_flux

W m-2

24h

Surface solar radiation downwards

169

J m-2

surface_downwelling_shortwave_flux_in_air

W m-2

24h

Surface thermal radiation downwards

175

J m-2

surface_downwelling_longwave_flux_in_air

W m-2

24h

Surface net solar radiation

176

J m-2

surface_net_downward_shortwave_flux

W m-2

24h

Surface net thermal radiation

177

J m-2

surface_net_downward_longwave_flux

W m-2

24h

Top net solar radiation

178

J m-2

toa_net_downward_shortwave_flux

W m-2

24h

Top incoming solar radiation

212

J m-2

toa_incoming_shortwave_flux

W m-2

24h

Top net thermal radiation

179

J m-2

toa_net_downward_longwave_flux

W m-2

24h

Eastward turbulent surface stress

180

N m-2 s

surface_downward_eastward_stress

Pa

24h

Northward turbulent surface stress

181

N m-2 s

surface_downward_northward_stress

Pa

24h

Evaporation

182

m of water equivalent

lwe_thickness_of_water_evaporation_amount

m

24h

Runoff (5)

205

m

runoff_amount  (5)

kg m-2

24h

Surface runoff

8

m

surface_runoff_amount

kg m-2

24h

Sub-surface runoff

9

m

subsurface_runoff_amount

kg m-2

(4) Large-scale and convective precipitation are not required if total precipitation is provided (and viceversa)
(5) Runoff is not required if both surface and sub-surface runoff are provided (and viceversa)

NOTES:

  • Accumulations in GRIB are made from the beginning of the forecast, while in netCDF they are made accordingly to the description contained in the cell bounds/methods
  • In netCDF, cell bounds and methods are also used to appropriately define maximum/minimum, etc.


 Pressure Levels Fields

At the following 12 pressure levels (hPa): 1000, 925, 850, 700, 500, 400, 300, 200, 100, 50, 30 and 10


GRIB

netCDF

time step

name

parameter ID

units

CF standard name

canonical units

12h

Geopotential

129

m2 s-2

geopotential_height

m

12h

Temperature

130

K

air_temperature

K

12h

Specific humidity

133

kg kg-1

specific_humidity

1

12h

Vorticity (relative) (*)

138

s-1

atmosphere_relative_vorticity (*)

s-1

12h

Divergence (*)

155

s-1

divergence_of_wind (*)

s-1

12h

U component of wind

131

m s-1

x_wind

m s-1

12h

V component of wind

132

m s-1

y_wind

m s-1

(*) Vorticity and divergence are not required if U and V are provided (and viceversa)




Ocean variables

List agreed on 28th October 2019 (Updated on 13th March 2020)

Time frequencyMonthly averages
Grid1x1-degree
(C3S atmosphere grid)
File formatnetCDF
(see encoding proposal)
nameCF standard nameunitscomments

Sea surface salinity

sea_water_practical_salinitypsu

Depth of 20C isotherm

depth_of_isosurface_of_sea_water_potential_temperature

m


Depth of 26C isothermdepth_of_isosurface_of_sea_water_potential_temperaturem
Depth of 28C isothermdepth_of_isosurface_of_sea_water_potential_temperaturem
Depth of 14C isothermdepth_of_isosurface_of_sea_water_potential_temperaturem
Depth of 17C isothermdepth_of_isosurface_of_sea_water_potential_temperaturem

Mean sea water potential temperature in upper 300 m

sea_water_potential_temperature

K


Mean salinity in upper 300 m

sea_water_practical_salinity

psu


Sea surface height above geoid

sea_surface_height_above_geoid

m


Mixed-layer depth defined by sigma theta 0.01 kg/m3

ocean_mixed_layer_thickness_defined_by_sigma_theta

m

  • Time-averaging: monthly average of mixed-layer depths calculated from hi-freq T,S (at least 6-hourly values)

Mixed-layer depth defined by sigma theta 0.03 kg/m3

ocean_mixed_layer_thickness_defined_by_sigma_theta

m

  • Time-averaging: monthly average of mixed-layer depths calculated from hi-freq T,S (24-hourly values are ok)

Sea ice thickness

sea_ice_thickness

m

Mean thickness where there is ice