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General requirements
Encoding format
- Participating Centres are expected to produce output fields in WMO GRIB2 data format and with consistent units. For more information please refer to WMO Manual on Codes
Parameters
Units
- All fields shall use units as defined in WMO Tables
Output frequency
- The model output steps should be between 1 and 12 hour
Missing values
- Bitmaps shall be used to indicate missing values.
Grid and resolution
- The fields have to be provided on a regular latitude‐longitude grid at the resolution that is best matching the native resolution of the direct model output.
- Grids are defined in GRIB2 using an accuracy of 1/1000000 (one millionth) of a degree.
- If several limited areas will be provided they should be merged into one larger area on a regular lat-lon grid, with a missing value indicator in the grid-points not covered.
GRIB2 encoding
All data must be encoded following the required rules described below to achieve fully compliant LC-WFV format from all centres.
Encoding software
ECMWF makes available a GRIB decoding library (ecCodes) for the benefit of the WMO community. ecCodes can be freely downloaded from here and the documentation can be found here. EcCodes provides a simplified access to GRIB2 headers through a set of virtual keys documented here.
Encoding details
The complete WMO compliant GRIB2 definitions of all wave parameters are linked in the page LC-WFV technical details
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For more general information about GRIB2 format please refer to WMO Manual on Codes .
Encoding details
Parameters
- 10 metre U wind component
- 10 metre V wind component
- Mean wave direction
- Mean zero-crossing wave period
- Peak wave period
- Significant height of combined wind waves and swell
General encoding
Specific details which should be encoded in GRIB2 sections 1 and 4:
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The codes below are based on WMO Manual 306 - WMO Codes. Each organization must be uniquely identified by its WMO code. If necessary to distinguish between two organizations using the same WMO code the Sub-Centre one which differs must be provided.
Organisation | Acronym | WMO Centre code | WMO |
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subCentre code | Centre acronym*1 | |||
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European Centre for Medium-Range Weather, UK | ECMWF | 98 | N/A | ecmf |
Met office, UK | UKMO | 74 | N/A | egrr |
Fleet Numerical Meteorology and Oceanography Center, USA | FNMOC | 58 | N/A | fnmo |
Environment and Climate Change Canada, Canada | ECCC | 54 | N/A | cwao |
National Centres for Environmental Prediction, USA | NCEP | 7 | N/A | kwbc |
Météo France, France | METFR | 84 | N/A | lfpw |
Deutscher Wetterdienst, Germany | DWD | 78 | N/A | edzw |
Bureau of Meteorology, Australia | BoM | 1 |
N/A | ammc | |||
Laboratoire D'Océanographie Physique et Spatiale, France | LOPS | 84 | 202 | lops |
Japan Meteorological Agency, Japan | JMA | 34 | N/A | rjtd |
Korea Meteorological Administration, Republic of Korea | KMA | 40 | N/A | rksl |
Puertos del Estado, Spain | PRTOS | 214 | N/A | lemm |
Danmarks Meteorologiske Institut, Denmark | DMI | 94 | N/A | ekmi |
National Institute of Water and Atmospheric Research, New Zealand | NIWA |
204 | N/A | niwa | ||
Det Norske Meteorologiske Institutt, Norway | METNO | 88 | N/A | enmi |
Servicio de Hidrografía Naval, Servicio Meteorológico, Argentina | SHNSM | 41 | N/A | sabm |
New Zealand MetService | NZMS |
69 | N/A | nzkl | ||
Servizio Meteorologico dell'Aeronautica Militare, Italy | METEOAM | 80 | N/A | cnmc |
Remarks:
*1 in ECMWF's eCcodes
Example of the validity type encoding
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