BUFR templates and GTS headers are currently identical for conventional VOS and automated VOS.
However, there are differences in the way data are relayed to shore, which may be important to understand for the users, and how the BUFR formats may evolve in the future.
Conventional VOS
Conventional VOS observations are sent ashore through different way.
The most traditional way consists in sending a FM13 SHIP message ashore through the Inmarsat GMDSS terminal of the ship. This terminal is mandatory on all ships over a certain tonnage. The communication is paid by the meteorological centre that receive the data. Short Access Code (SAC) 41 may be used.
Two other use of GMDSS terminals exists: for AMVER SEAS messages (NOAA) and for E-SURFMAR half compression messages. SEAS messages require the terminal is put in Data Mode whilst E-SURFMAR messages look like BinHex characters. In both case, observation data are binary (i.e. compressed). The conversion to GTS codes (FM13 SHIP and FM94 BUFR) is ensured at the processing centre that receives the raw data. Metadata may be added to observation data there. Communications are also paid by meteorological services. Raw E-SURFMAR dataformat #101 was designed to save communication costs while at the same time being closer to BUFR requirements in matter of accuracy and meeting new requirements for ship data (VOSClim parameters).
More and more observation messages are sent ashore by email at the ship expenses. For the moment, most of them are FM13 SHIP messages.
By mid-2014, several centres receiving FM13 SHIP messages from the ships, convert them into FM94 BUFR without any metadata.
SEAS and E-SURFMAR raw data are converted in FM13 SHIP and FM94 BUFR (information to be checked with regards to SEAS). A few metadata, such as the level of the different main sensors as well as the type of the station are added in BUFR messages to E-SURFMAR observation data prior to their transmission onto the GTS.
VOS with Shipborne-Automatic Weather Station (S-AWS)
In general, S-AWS send their observations ashore thanks to their own transmitter. This latter may be Inmarsat-C, Iridium SBD, Meteosat DCP, Argos... Data may be raw (binary or alphanumeric) or FM13 SHIP messages (in the case of Meteosat DCPs). In several instances, FM13 SHIP messages are forwarded onto the GTS as they are and possibly converted in BUFR without any metadata added.
Raw data from many European S-AWS (E-SURFMAR dataformat #100) are converted in both WMO codes (FM-13 SHIP and BUFR). In case of BUFR, metadata are added to observation data prior to the GTS transmission.
BUFR templates in use
BUFR template used for ship data is presently TM308009 (B/C10). It should be soon replaced with TM308014, noting another (shorter) template is being proposed for S-AWS VOS.
GTS headers for ship data start with character string 'ISS'. A draft of template TM308014 is available on line. Some minor clarifications occurred since this version was published.
Ship observations - Survey on December 10th, 2018 (Météo-France)
Total number of distinct identifiers in (BUFR + FM-13 SHIP), other than SHIP: 1,293
Total number of distinct identifiers in (BUFR + FM-13 SHIP) with a moored buoy number: 312
Total number of distinct identifiers in (BUFR + FM-13 SHIP) with a drifting buoy number: 0
Total number of distinct ship (non-numeric) identifiers (excluding the idenfitier "SHIP", which refers to numerous ships that do not want to disclose their identity) in (BUFR + FM-13 SHIP): 981, distributed as follows:
- 821 both encoded in BUFR and in FM-13 SHIP formats, Beware: double encoding may be the result of TAC <> BUFR (either way) conversion, and not the result of a 'genuine' encoding (from raw data) in both formats. This represents 5705 reports in BUFR format and 5545 reports in FM-13 SHIP format.
- 102 only encoded in FM-13 SHIP format (these are produced on the GTS mostly by USA, Australia, Canada, and India). This represents 1234 reports in FM-13 SHIP format.
- 58 only encoded in BUFR format (these are produced on the GTS mostly by Norway (mostly oil rigs/fixed platforms) and France (Mercury stations)). This represents 781 reports in BUFR format.
Ship observations - Survey on August 6th, 2016
The table here above shows the number of VOS (fixed stations excluded) for which the observations were received by Meteo-France on the 6th of August. Figures are shared by the WMO code which was used: either FM13 SHIP or FM94 BUFR (templates TM308009)This table does not refer to the number of observations which were received. One may consider that 83% of VOS reports are sent onto the GTS in BUFR with template TM308009. Template TM308014 should be adopted in November 2016. Some meteorlogical services are probably waiting its official availability to report VOS observations in BUFR.
Ship BUFR data - Survey on May 6th, 2015
Number of VOS stations having reported ar least one observation on that day
- BUFR : Number of ships using Template TM308009; FM13 only : Number of ships not reporting in BUFR
- This survey is valid for both conventional VOS and shipborne AWS
- Stations having an identifier made of numbers only were not considered. However, some oil rigs or other fixed stations may have been taken into account (e.g. for Norway)
- It clearly appears that BoM (AMMC), Environment Canada (CWAO), IMD (India), NOAA (KWBC)... are in late to produce ship BUFR data