Introduction
Starting from the The tables shown on this page summarize the list of parameters variables requested in the ITT (see here), a review process on them was carried on, and some modifications were proposed to the different providers to C3S seasonal activity (ECMWF, Met Office, MeteoFrance, DWD and CMCC). Additionally, the original list of parameters was to a certain extent incomplete as it just used GRIB parameter codes to describe the variables, in a context where most of the contributors are currently using (or will do in the near future) netCDF format for their provision to C3S.
Taking all of that into account, a revisited list of parameters to be used by the seasonal forecasting providers has been summarized in the tables below, including information for encoding both in GRIB and netCDF
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Due to the current characteristics of the C3S service, in its transition from the Proof-of-Concept phase to the Pre-operational phase, this list needs to be understood as a reference of what should be mandatory in the future provisions of data to C3S. In this sense, comparing the data streams' contents from the providers and what is included in the list of requested variables, some slight differences are tolerated, even they are not desirable. |
Requested variables from providers
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 |
24h | Total column water vapour | 137 | kg m-2 | atmosphere_mass_content_of_water_vapor | kg m-2 |
24h | Total column cloud liquid water | 78 | kg m-2 | atmosphere_mass_content_of_cloud_liquid_water | kg m-2 |
24h | Total column cloud ice water | 79 | kg m-2 | atmosphere_mass_content_of_cloud_ice | kg 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 frequency | Monthly averages |
Grid | 1x1-degree (C3S atmosphere grid) |
File format | netCDF (see encoding proposal) |
name | CF standard name | units | comments |
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Sea surface salinity | sea_water_practical_salinity | psu | |
Depth of 20C isotherm | depth_of_isosurface_of_sea_water_potential_temperature | m | |
Depth of 26C isotherm | depth_of_isosurface_of_sea_water_potential_temperature | m | |
Depth of 28C isotherm | depth_of_isosurface_of_sea_water_potential_temperature | m | |
Depth of 14C isotherm | depth_of_isosurface_of_sea_water_potential_temperature | m | |
Depth of 17C isotherm | depth_of_isosurface_of_sea_water_potential_temperature | m | |
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 |
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Mixed-layer depth defined by sigma theta 0.03 kg/m3 | ocean_mixed_layer_thickness_defined_by_sigma_theta | m |
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Sea ice thickness | sea_ice_thickness | m | Mean thickness where there is ice |
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