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About 86% of stations now report in BUFR, in the last quarter Ukraine and Kazakhstan started sending BUFR reports. Coverage for Europe is essentially complete apart from three NMSs (Bulgaria, Moldova and the Former Yugoslav Republic of Macedonia). For some countries stations/reports designated as "additional data" only are received in TAC but not in BUFR. Light blue markers indicate that fewer BUFR reports are received than SYNOP reports - in most cases the BUFR is six-hourly but the SYNOPs are three-hourly. (Unlike TEMP data, below, alphanumeric SYNOP reports reformatted into BUFR are generally acceptable.)
Countries that have ceased TAC SYNOP transmission on the GTS are shown green (this is not fully up-to-date) and labelled 'Post SYNOP'. ECMWF is assimilating BUFR surface reports from these countries plus some others.
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The plot below distinguishes native BUFR (stations reporting valid radiosonde drift positions): high/low resolution (dark/light blue, using 300 level threshold) from reformatted TEMP (orange). There are now high resolution reports from all continents.
Almost all reformatted TEMP reports are sent as separate parts (A/B/C/D), this is contrary to the BUFR coding rules (there should be a single report containing data for the whole ascent) and reformatted TEMP reports are regarded as unusable by ECMWF and most other NWP centres. BUFR reports generated directly from the radiosonde raw data are much better.