What is a pre-existing station?

It is a station that was operational before WIGOS Station Identifiers (WSI) entered in force as identifiers for WIGOS stations. It is a station with a Traditional Station Identifier (TSI) registered in Vol. A up until the 1 July 2016.

The pre-existing stations have been assigned WSIs by WMO Secretariat with the following convention

Issuer of identifier values	Category of station identifier	Issue number	Local identifier
20000	World Weather Watch land station with sub-index number (SI) = 0	0: station defined in Weather Reporting (WMO-No. 9), Volume A, on 1 July 2016 Any other positive number: to distinguish between different observing facilities that used the same station identifier in the past	Use the block number II and station number iii, a five-digit number with leading zeroes ). Example: station 60351 would be represented by 0-20000-0-60351
20001	World Weather Watch land index	0: station defined in Weather Reporting, Volume A, on 1 July 2016	Use the block number II, and the station number iii, as a single five-digit number IIiii (with leading zeroes). Example: upper-air station 57816 would be represented by 0-20001-0-57816
20002	World Weather Watch marine platform (moored or drifting buoy, platform, etc.)	0: platform for which the identifier was in use on 1 July 2016	Use the region/platform number combination A1bwnbnbnb. Examples: The data buoy 59091 would be represented by 0-20002-0-59091 The World Weather Watch list of data buoys has two buoys with identifier 13001. The buoy most recently used at the time WIGOS station identifiers  were  introduced is allocated 0-20002-0-13001 and the second is issued identifier 0-20002-1-13001
20003	Ship identifier based on the International Telecommunication Union call sign	0: ship to which the identifier was most recently allocated on 1 July 2016 Any other positive number: to distinguish between different ships that used the same ship identifier at different times	Ship call sign Example: the (now obsolete) weather ship C7R would be represented by 0-20003-0-C7R
20004	Ship identifier – issued nationally	0: ship to which the identifier was most recently allocated on 1 July 2016 Any other positive number: to distinguish between different ships that used the same ship identifier at different times	Ship identifier Example: the fictitious ship XY123AB would be represented by 0-20004-0-XY123AB
20005	AMDAR aircraft identifier	0: aircraft to which the identifier was most recently issued on 1 July 2016 Any other number: to distinguish between different aircraft that used the same aircraft identifier at different times	Aircraft identifier Example: aircraft EU0246 would be represented by 0-20005-0-EU0246

What is a new station?

It is a station for which a WSI has been issued after 1 July 2016, is not in Vol. A and does not have an official TSI. There are many stations exchanging data on GTS with unofficial TSI, not registered in OSCAR and without a WSI. New stations cannot be assigned a WSI in the range 20000-20001.