WIGOS Learning Portal: Clarification on wind direction code 99 in WDQMS

Dear WDQMS experts,

I am reviewing data for a station in WDQMS. For a full month, we expect 744 values for the wind direction to have the station indicator appear in green. Out of these 744 observations, 261 have the wind direction coded as 99.

I understand that 99 represents a variable wind, not missing data. However, in WDQMS, the station indicator appears in orange, which seems to treat the 99 values as missing.

Could you please clarify how WDQMS interprets these 99 values? Should variable wind be considered as valid data for the station status, or is it automatically counted as missing?

Thank you very much for your guidance.

Best regards,

Re: Clarification on wind direction code 99 in WDQMS

от Cristina Prates - понедельник, 23 февраля 2026, 16:37

Dear Sonia,

Thank you very much for your pertinent question.
WDQMS results are derived from the data assimilation (DA) systems of various NWP models, and different modules may handle observations in different ways. The statistics provided in WDQMS are calculated for the zonal and meridional wind components (u and v), as these are the variables that are assimilated and provided by NWP Centres. Naturally, when wind direction is reported as variable, the u and v components cannot be computed by the DA.
That said, I would expect the ECMWF availability results not to be affected by this. When variable wind is reported, the departures for u and v cannot be calculated for that specific observation; however, the wind observation itself should not be considered missing. To investigate this further, could you please provide a concrete example where you have encountered this issue? For instance, a station ID that reported variable wind on a specific day.
With such an example, I will be able to examine the case in more detail.
Kind regards,
Cristina