WMO Codes and Migration to TDCF (www.wmo.int/pages/prog/www/WMOCodes.html) provides the formal definition of the codes and links to the templates and regulations, which are available online (www.wmo.int/pages/prog/www/WMOCodes/WMO306_vI2/TemplateExamples.html). An important feature is that a BUFR radiosonde message should contain all the data from an ascent (or all the data up to 100 hPa for the preliminary report); BUFR was not designed to contain a single part (A, B, C, or D) converted from TEMP. Unfortunately, converting single parts was/is common practice and the cause of most invalid radiosonde BUFR reports. In June 2015 WMO CBS reiterated that converted single parts do not conform to BUFR regulations and also stated that “It is preferable to use the highest resolution information available directly from radiosonde systems when compiling a report in BUFR”.  There have been various attempts to merge together TEMP parts A, B, C and D and convert the profile to BUFR, none have been entirely successful.  Data converted from Traditional Alphanumeric Codes (TAC) will not include high vertical resolution or the position of each level ("drift" locations) which allows better usage of the profiles in NWP.  Various radiosonde manufacturers (Vaisala, MeteoModem, Graw and InterMet, hopefully others over time) provide software to generate high resolution BUFR reports - generally of good quality.  In some other cases the National Meteorological Service has taken the lead to generate high resolution BUFR reports directly from raw radiosonde data. 

Example of invalid BUFR data converted from TAC: light blue solid lines (black solid lines are from the alphanumeric report, dashed lines from the ECMWF model).  The caption "BUFR     4   25   13  10" means that there were four separate BUFR reports with between 4 and 25 levels.  

Example of good high resolution BUFR data: dark blue solid lines (dashed lines from the ECMWF model).

(Partially) missing BUFR profiles

For some stations we receive no BUFR reports, for others we receive BUFR some of the time.  There are also stations from which we receive BUFR only from the surface to 100 hPa (the preliminary BUFR reports) but not the whole profiles.

Other BUFR problems

Occasionally there are other problems such as the use of a BUFR descriptor that our decoder doesn't recognise.  This may be due to a mistake on the part of the data provider but there are also cases where the ECMWF decoder (ecCodes) needs modifying to take account of new/unusual features.  If you are putting data onto the GTS that ECMWF doesn't appear to be decoding then please let us know the collecting centre (CCCC) and bulletin header of the reports.