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Find in this page technical specification of the required input data and processing workflow.

Parameters

• Output type:  forecast

  • only one forecast product per centre is expected for verification - the best available one for the common inter-comparison

• Output time: 00, 6, 12, 18 UTC (depending on availability)

• Output frequency: between 1 and 6 hours (including step 0 encoded as forecast type as well)

  • the model output steps should be the shortest available
• Wave parameters should be obtained from the full 2-D spectrum (we stress this fact as there seems to be some confusion about wave parameters' names and definitions even in the latest WMO GRIB2 code tables)

• Follow the links for exact GRIB2 WMO compliant definitions
• *1 valid in ECMWF's ecCodes only

Encoding

All details about the required data format can be found in the page Encoding details.

Sample data

• Providers are asked to provide full sample data from one model run containing all expected parameters, steps, forecast types etc.
• Naming convention for sample data:
  wave_<centre WMO origin>_<YYYYMMDDRR>_<prod/test>_fc.grib2
  prod/test ... production or test version of the data
  fc ... forecast (step 0 should be also encoded as of forecast type)
• Merge all parameters from all steps for given model run and output type into one file:
  e.g. wave test forecasts from ECMWF on the 1st of September 2017, 12Z  => wave_ecmf_2017090112_test_fc.grib2
• Put sample data on ecgate to a directory with reading permission
  • alternatively use any other downloadable location (e.g. google drive)

  • alternatively use this ftp:

    Show If
    special @anonymous
    Alert Log in to see ftp details

    
    

    Show If
    special @authenticated
    Code Block host: ftp.ecmwf.int user: observations passwd: observations2013 directory: wave

    
    

• The naming convention for future production data might change

Production data acquisition

• The data will be pulled via ftp from an agreed server location at the data producer's site.
• The ECMWF's acquisition system will be used for handling the production data exchange.
• Participants are committed to guarantee a steady and reliable provision of their data and to communicate any relevant changes.
• The support mailing list on provider's side will be required to allow smooth communication related to common production issues in the future.

Contact

Aim of this page :

1. a table with NCEP data: GRIB sample (only one message and one parameter), encoding explained (not only parameter we need to have all the significant descriptions including the geography)
2. A table with what we aim to have from the partners. Description in words, GRIB2 coding (not only parameter also all other relevant coding details), possibly an example of grib for each parameter
3. A common description of the grid we are going to ask the users. We said that this is going to be a global domain. I think we also need a bitmap.

After talking with  Jean Bidlot  we concluded that what we are asking our contributors for in GRIB2 language is :

...

parameter

( WMO GRIB2 - TABLE 4.2-10-0)

...

parameter
Number 

...

. regular lat-long grid

. grid spacing free for the contributor to chose

. not need to be global

. bitmap ?

...

Code table4.5 – Fixed surface types and units

    ??

102 Specific altitude above mean sea level

103  Specified height level above ground

...

Significant height of combined
wind waves and swell

...

typeOfFirstFixedSurface = 1

[Ground or water surface]

101  Mean sea level

...

230.140

Mean wave direction

( Mean wave direction )

...

Direction of combined wind
waves and swell

...

Mean  wave direction derived from the vector mean direction from the wave variance spectrum.

NCEP sample file  multi_1.glo_30mext.t00z.f000.grib contains: 

...

parameter Name

...

parameter
Number

...

vertical level

(grib2/tables/2/4.5.table)

...

 time

(grib2/tables/2/4.4.table)

...

u-component of wind

_{(WMO GRIB2 compliant)}

...

0

...

scaledValueOfFirstFixedSurface = 1

typeOfSecondFixedSurface = 255 [Missing ]

scaleFactorOfSecondFixedSurface = 0

...

gridDefinitionTemplateNumber = 0 [Latitude/longitude]
latitudeOfFirstGridPoint = 90000000
longitudeOfFirstGridPoint = 0
latitudeOfLastGridPoint = -77500000
longitudeOfLastGridPoint = 359500000
iDirectionIncrement = 500000
jDirectionIncrement = 500000

...

IndicatorOf

UnitOfTimeRange = 1 [Hour]   

...

v-component of wind  

_{(WMO GRIB2 compliant)} (grib2/tables/2/4.2.0.2.table)

...

Significant height of 
combined wind waves and swell

_{(WMO GRIB2 compliant)}

...

height.grib2

WMO tables :

http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc.shtml

http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_table4-2-10-0.shtml

...