...
Warning to data users: Two timestamps are included in each drifing buoy observation message. Each timestamp is preceded by its related time significance (BUFR element 0 08 021). It must be noted that, in template TM315009, the first timestamp is this of the last known position (value is 26). This of the observation (time significance = 25), also called "nominal reporting time" is in second position. Do not confuse both.
...
Buoy BUFR data - Survey on end of June 2016 (ECMWF)
This map shows the data buoys (moored and drifting) that reported in FM18 and BUFR (91% in all), in FM18 only (2%) and in BUFR only (7%) between the 13th and the 29th of June 2016 (according to data received at ECMWF). That means that 98% of buoy data are henceforth sent in BUFR. The buoys reporting in FM18 only were mainly Indian moored buoys (DEMS) and Japanese drifting buoys (RJTD). During the coming months, more and more data will be sent in BUFR only (pink dots). Met Office asked to prolong the date of end for FM18 messages to the 1st of November 2016.
Warning: Moored buoys reporting in FM13 and/or in BUFR with ship template (TM308009) does not appear on this map.
Buoy BUFR data - Survey on May 16th, 2016 (ECMWF)
This map shows the data buoys (moored and drifting) that reported in FM18 and BUFR (75%92% in all), in FM18 only (2%) and in BUFR only (23%6%) on the 16th of May 2016 (according to data received at ECMWF). That means that 98% of buoy data are henceforth sent in BUFR. The buoys reporting in FM18 only were mainly Indian moored buoys (DEMS) and Japanese drifting buoys (RJTD). During the coming months, more and more data will be sent in BUFR only (green and pink dots). It must be noted that most of the FM18 data should disappear from the GTS on the 1st of September 2016.
...