The WMO FM-94 BUFR, Binary Universal Form for the Representation of Meteorological data, is a binary code designed to represent, employing a continuous binary stream, any meteorological data. It has been designed to achieve efficient exchange and storage of meteorogical and oceanographic data. It is self defining, table driven and very flexible data representation system, especially for huge volumes of data.
ECMWF provide BUFR User's Guide
205KB and BUFR Reference Manual 804KB that describes latest BUFR tables and ECMWF observation types and subtypes. For each subtype there is a template describing the observation.
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