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- Each partner will provide their eps data on a 1.5/1.5 regular lat-lon grid for both ocean and atmosphere. First grid point is 90N 0E. The data will be archived first from west to east to west (OE to 358.5), and then from North north to South south (90N to 90S). The related GRIB 2 meta data called scanning mode should equal to 0.
Scanning mode 0
- i scans positively (west to east)
- i points are consecutive
- j scans negatively (north to south)
- i scans positively (west to east)
- Grids are defined in GRIB2 using an accuracy of 1/1000000 (one millionth) of a degree. If this accuracy is not sufficient to describe your grid (latitude/longitude of first and last points, as well as grid increments) without loss of information, you can use a GRIB2 feature that provides a way to describe any regular grid. See the page on encoding global latitude/longitude grid for more details.
Ocean parameters
- follow the same rules but the data is on a 1.0/1.0 regular lat-lon grid
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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.
S2S GRIB2 checking tool
The so called tigge_check tool is a part of ecCodes package. It should be used to validate all GRIB2 files prepared for S2S (the option "-s" for the real-time outputs and option "-s -r" for S2S reforecast files). The tool is checking all encoding details so that only fully compliant S2S files following exactly required definitions would pass. Find more information about the tool in the page Data encoding checking tools
Encoding
1) S2S Production status of processed data
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- 6: S2S operational products
- 7: S2S test products
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S2S extension (Section 2)
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| Section 1 | |||
|---|---|---|---|
| Octets | Example perturbed | Example control | |
| 21 | type of processed data | =4 | =3 |
| Ensemble (section 4, template 4.61) | |||
|---|---|---|---|
| Octets | Example perturbed | Example control | |
| 8-9 | product definition template number | 1/11* (real-time) 60/61* (reforecast) | 1/11* (real-time) 60/61* (reforecast) |
| 35 | type of ensemble forecast | = 255 (missing) | = 255 (missing) |
| 36 | perturbation number | = 7 | = 0 |
| 37 | number of forecasts in ensemble | = 51= | 51 |
- statistically processed (typeOfStatisticalProcessing is set up)
3) Time component and reforecasts
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(*) ecCodes version>= 2.13.0 is needed to see correct MARS meta data