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Mean zero-crossing wave period issue at step 0
1. Brief description:
Due to the bug in the computation of the second moment and the zero moment of the frequency spectrum (inconsistent diagnostic methods, truncation errors due to limited GRIB precision for the initial conditions) the values of the mean zero-crossing wave period at step 0 are wrong . Affected data:
- 0Z: 2018-11-01...2018-11-05
- 12Z: 2018-10-31...2018-11-04
2. Recommendation:
Do not use the affected data.
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Wrong peak wave period data
1. Brief description:
Due to the bug in in the determination of the peak wave period values all available data can be affected.
2. Recommendation:
Do not use that parameter until the bug fix is implemented by the provider.
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Different GRIB2 packing than simple (cwao, rjtd, rksl data only)
1. Brief description:
It has been discovered that input data from three providers are using advanced (complex) GRIB packing. It might be useful to have smaller files generally but unfortunately it can create issues in some GRIB tools or for users as e.g. more CPU is needed to process data. For archiving purposes the hardware (tape) packing is used which is a better solution for number of reasons.
2. Recommendation:
Be aware that the centres below (have) used advanced packing. It does not affect data values at all but users can experience slower data processing in some scenarios.
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The wind speed discrepancy at day 5
Description:
The intensity fields (wind speed) exhibit some differences at day 5 comparing to other models. The explanation by the provider is that DMI gets access to ECMWF wind fields with a delay so large that the previous forecast.must be used for the day 5.
To illustrate the problem see the comparison of 10 m wind forecasts from ECMWF (ecmf) and DMI (ekmi) for one case study (ecmf-10m-V ecmf-10m-WS ekmi-10m-V ekmi-10m-WS). Because of the delayed access to ECMWF winds the +120h ecmf data is thus compared to +132h ekmi data (using the analysis 12h earlier) as explained by the provider.