WIGOS Learning Portal: Surface Data Quality

Hello, I am trying to understand the source of error that shows in this station (attached), for surface pressure. This behavior from models is repeated since the beginning of the web tool-

You can see that only 1 model (DWD) shows no error, while the other models have exceptionally large systematic errors.

IStation: ENCARNACION - WIGOS-ID: 0-20000-0-86297

All centres use TAC

Thank you

Martina

Re: Surface Data Quality

by Cristina Prates - Thursday, 14 May 2020, 10:34 AM

Dear Martina,

This is probably a metadata issue that is impacting the quality of the observation. The model uses the barometer height (or the station height if barometer height is not available) to derive the Background value (in this case the surface pressure at the station level). Therefore, if the height is not correct a systematic error will show in O-B statistics (well illustrated here by three of the models). I can not find any information on the station and barometer height in OSCAR/Surface (https://oscar.wmo.int/surface/index.html#/search/station/stationReportDetails/0-20000-0-86297). Normally, station height information should appear under "Station characteristics" on the line "Coordinates" after Lat, Lon information and that is not available for 86297 (Coordinates: 27.3000°S, 55.9000°W ). ECMWF is using 90m as station height, which I presume comes from the Vol A legacy and not from OSCAR/Surface. DWD is probably using a more accurate value for the station height.
Thanks,
Cristina Prates

Re: Surface Data Quality

by Rainer MAERZ - Thursday, 14 May 2020, 1:48 PM

Dear Martina - and Christina with thanks for the Explanation.
I had a closer look on data and metadata and found some proof that the observations are made on the Airport approx. 10 km northward since Nov. 2014 . on that date the difference between Station and msl-pressure raised from 10 to 24 hPa. Comparision of todays Reports in both codes METAR and SYNOP Show similarity for many Parameters (wind, Temp, dewpoint, pressure, even current weather as fog dissipated). So best practice would be to update OSCARs metadata and everything should be fine .... hope that my suggestion is correct ;-)
best regards and hope everyone will stay sound in those times
Rainer

Re: Surface Data Quality

by Martina Suaya - Thursday, 14 May 2020, 2:03 PM

Thank you both! IIs evident that this tool will help a lot in the normalization of metadata for the beefits of many.

Best

Martina