Rules for allocating WMO numbers

Programmes > AMP > MMOP > Observations > DBCP > WMO numbers rules

Rules for allocating WMO numbers

What is a WMO number and how to get/allocate WMO numbers?

WMO numbers are allocated for ocean platforms reporting on GTS. WMO numbers are allocated depending upon platform type, and deployment area (see table and map below). Considered platform types are drifting buoys, fixed ocean observing platforms (Moored buoys, rigs and offshore platforms), ocean reference sites, autonomous vehicles (i.e. gliders, saildrones), profiling floats (e.g. Argo), and marine animals equipped with instrumentation for measuring geo-physical variables .

General form of a WMO number is [V]A₁b_wnnn or [V]A₁b_wnnnnn:

• The letter "V" is optional, and is used only for allocating numbers to virtual platforms (e.g. reference points). The same rules as below then apply to the remaining part of the WMO number (A₁b_wnnn or A₁b_wnnnnn). When the letter "V" is used,it shall always be included with the WMO number as it is an integral part of it in that case. The corresponding "virtual observational" reports shall by no way be distributed on the GTS as they are not real-observations.
  
• A₁b_w represents the WMO regional association area (A₁) and the sub-area (b_w) belonging to the area indicated by A₁ where the platform is being deployed (regional association area not defined for marine animals; sub-area not defined for profiling floats, ocean sites, autonomous vehicles (i.e. gliders, saildrones), and marine animals). Figure 1 provides for the possible values of A₁b_w (see also note 1 concerning the peri-Antarctic area).
  

• nnn or nnnnn is the serial number assigned to the platform for that WMO region and sub-area corresponding to the deployment area. Serial numbers are allocated depending upon platform type as shown in the table below.The rules for using of the short or extended form are defined in the table below.
  
  
• Numbers in the form A₁b_wnnn are considered equivalent to the form A₁b_w00nnn. In addition, in order to avoid allocating a 7-digit WMO number to a new buoy with this 7-digit number being equivalent to a 5-digit WMO number of an existing buoy, all newly allocated 7-digit WMO numbers in the form A₁b_wnnnnn have always the nnnnn part ≥ 1000 (in other words the 7-digit numbers where nnnnn < 1000 are reserved for the 5-digit equivalence.)
  

Reallocation, uniqueness:

• Prior to year 2016, for drifting and moored buoys using the short form A₁b_wnnn, provided that buoy type and deployment area does not change, WMO number can be reallocated to a new buoy, 3 months at the earliest after the end of the buoy operational life-time. In the contrary, if your buoy programme stops and you do not intend to deploy buoys in the future, please release the WMO numbers to your National Focal Point.
  
• Starting from year 2016, members are requested not to reallocate WMO numbers for all types of platforms using either the short form A₁b_wnnn, or reporting in BUFR or CREX using the extended form A₁b_wnnnnn.

 

Table 1: rules for WMO number allocation

Platform type	Format	Reporting code form	Deployment area	Serial no.	Reallocation	Comment
Drifting buoys	A1bwnnn	BUOY, BUFR, CREX	A1=WMO region, bw=sub-area	nnn: 500 to 899	Yes, after 3 months	Surface drifting buoys, http://www.jcommops.org/dbcp/ Twin number A 1bwxxx with xxx=nnn-500 can be used for a fixed ocean observing platform.
Drifting buoys (table driven codes only)	A1bwnnnnn	BUFR, CREX	A1=WMO region, bw=sub-area	nnnnn: xx500 to xx899 with xx: 00 to 99	No, unique numbers	Surface drifting buoys, http://www.jcommops.org/dbcp/ No twin number (i.e. A 1bwxxxxx with xxxxx=nnnnn-500 allocated to a fixed ocean observing platform separately/ independently ).
Fixed ocean observing platform (Moored buoys, rigs and offshore platforms)	A1bwnnn	BUOY, BUFR, CREX, SHIP	A1=WMO region, bw=sub-area	nnn: 000 to 499	Yes, after 3 months	Fixed ocean observing platforms, including surface meteorological and/or oceanographic buoys, rigs and offshore platforms. http://www.jcommops.org/dbcp/ Twin number A 1bwxxx with xxx=500+nnn (where nnn <900)can be used for a drifting buoy.
Fixed ocean observing platform (Moored buoys, rigs and offshore platforms) (table driven codes only)	A1bwnnnnn	BUFR, CREX	A1=WMO region, bw=sub-area	nnnnn: xx000 to xx499 with xx: 00 to 99	No, unique numbers	Fixed ocean observing platforms, including surface meteorological and/or oceanographic buoys, rigs and offshore platforms. http://www.jcommops.org/dbcp/ No twin number (i.e. A 1bwxxxxx with xxxxx=500+nnnnn (where nnnnn<nn900)allocated to a drifter separately/ independently ).
Ocean sites	A184nn	BUOY	A1=WMO region	nn: 00 to 99	No, unique numbers	Ocean reference sites, http://www.oceansites.org/ bw forced to 8 Twin number A189nn can be used for autonomous vehicles (i.e. glider, saildrone)
Ocean sites (table driven codes only)	A18xxnnn	BUFR, CREX	A1=WMO region	If A1=4 or xx=00, then nnn: 400 to 499 else nnn: 000 to 499	No, unique numbers	Ocean reference sites, http://www.oceansites.org/ bw forced to 8 No twin number (i.e. A18yyyyy with yyyyy=zzzzz+500 allocated to autonomous vehicles (i.e. glider, saildrone) separately/ independently )
Autonomous vehicles (i.e. gliders, saildrones..)	A189nn	BUOY, TESAC, BUFR, CREX	A1=WMO region	nn: 00 to 99	No, unique numbers	bw forced to 8 Twin number A184nn can be used for an OceanSITE
Autonomous vehicles (i.e. gliders, saildrones..) (table driven codes only)	A18xxnnn	BUFR, CREX	A1=WMO region	if A1=4 or xx=00 then nnn: 900 to 999 else nnn: 500 to 999	No, unique numbers	Ocean reference sites, http://www.oceansites.org/ bw forced to 8 No twin number (i.e. A18yyyyy with yyyyy=zzzzz-500 allocated to an OceanSITE separately/ independently )
Profiling floats	A19nnnnn	TESAC, BUFR	A1=WMO region	nnnnn: 00000 to 99999	No, unique numbers	bw forced to 9 Profiling floats (including Argo, http://argo.jcommops.org/) When using character code TESAC, the WMO number is preceded with the letter Q.
Marine animals	99nnnnn	TESAC, BATHY, BUFR, CREX	Any	nnnnn: 00000 to 99999	No, unique numbers	A1 forced to 9; bw forced to 9. When using character code TESAC or BATHY, the WMO number is preceded with the letter Q.

Obtaining WMO numbers: Blocks of WMO numbers are allocated to the countries by the WMO Secretariat (see WMO block allocation here). National Focal Points for buoy programmes are responsible for allocating the WMO numbers nationally.

For obtaining WMO numbers, contact your National Focal Point and provide him/her with following information and he/she will provide you with the required WMO numbers:

1. Platform type (drifting buoy, fixed ocean observing platform, OceanSITE, profiling float)
2. Number of platforms of the type above, and for each platform:
3. Approximate deployment area (see map below)
4. International programme in which the buoy participates, if any.

If there is no National Focal point in your country, then you can contact the WMO Secretariat directly (see contact details here), the Technical Coordinator of the DBCP (buoys), or the Argo Technical Coordinator (profiling floats). The latter two (see contact details here) can also contact the appropriate National Focal Point on your behalf if desired.

Figure 1: WMO regional association area (A₁, 1st digit) and sub-area (b_w, 2nd digit) for allocation of WMO numbers based upon buoy deployment area

Notes:

1. For the peri-Antarctic regions, A₁ is coded '7' in FM-18 BUOY code and the latest verison of the FM-94 BUFR template for buoy data. A₁ used to be coded '0' for this region in an older version of the FM-94 BUFR template (BUFR code table 0 01 003), in which case it is advised to rebuild the complete WMO number with the '7' for the A₁ part and for use, storage, and further exchange purposes.
   
   
2. Drifting and fixed ocean observing platforms (moored buoys, rigs and offshore platforms) : When using the short form (5-digit numbers), a pair of WMO numbers is allocated each time to a country; one number can be used for a fixed ocean observing platform, and the other one for a drifting buoy. Only the fixed ocean observing platform number (i.e. in the series nnn from 000 to 499) is indicated when allocating the pair. The drifting buoy number is automatically deduced by adding 500 to the indicated number (i.e. the drifting buoy number will be in the form of A₁b_wxxx with xxx = 500+nnn). Until 1997 WMO numbers in the series nnn from 300 to 350 were allocated to TAO buoys. Until 1997 WMO numbers in the series nnn from 400 to 499 were allocated to WOCE buoys. As of 2007, per DBCP-22 recommendation, extended WMO numbers (7-digit numbers) may be used provided the data are being reported in BUFR or CREX. WMO numbers are not allocated in pairs in case of the extended form.
   
   
3. OceanSITES and Autonomes vehicles (i.e. gliders, saildrones): When using the short form (5-digit numbers), a pair of WMO numbers is allocated each time to a country; one number can be used for an OceanSITE, and the other one for autonomous vehicles (i.e. gliders, saildrones..). Only the OceanSITE number (i.e. A₁84nn) is indicated when allocating the pair. The autonomous vehicle number is automatically deduced by adding 500 to the indicated number (i.e. the glider/saildrone number will be in the form of A₁89nn). As of 2007, per DBCP-22 recommendation, extended WMO numbers (7-digit numbers) may be used provided the data are being reported in BUFR or CREX. WMO numbers are not allocated in pairs in case of the extended form.
   
   
4. Profiling floats: Observational data from profiling sub-surface floats deployed under Argo and similar projects are distributed on the GTS in TESAC or BUFR code. The Data Buoy Cooperation Panel (DBCP) has developed an extension of the existing buoy identifier system to facilitate easy identification of the reports from these floats, as well as retain a unique ID number for all floats deployed (without recycling). When using TESAC, the identifier is to be used in place of the ships call sign, “D..D” (i.e. not the buoy identifier) with the addition of the letter Q as the first character: QA₁9nnnnn. Letter Q indicates in the TESAC message that the report is not from a ship; at the same time letter Q is not strictly speaking part of the WMO number. The seven-digits float identifier in TESAC was implemented for all floats deployed on and after 1 June 2001 (between December 1998 and June 2001, numbers allocated to Argo floats were of the form A₁9nnn). WMO numbers have to be obtained BEFORE deployment. When using BUFR, the letter Q is not being used as it is not part of the WMO number.
   
   
5. Marine animals: Marine animals equipped with observing instruments may distribute the geo-physical variable measures using BATHY, TESAC, BUFR, or CREX code forms. To avoid confusion with other types of marine observing stations, WMO numbers in the form 99nnnnn are being allocated. These numbers will be allocated as unique numbers as long as there are numbers available. When using BATHY or TESAC, the identifier is to be used in place of the ships call sign, “D..D” (i.e. not the buoy identifier) with the addition of the letter Q as the first character: Q99nnnnn. Letter Q indicates in the BATHY or TESAC message that the report is not from a ship; at the same time letter Q is not strictly speaking part of the WMO number. The seven-digits marine animal identifier in BATHY or TESAC was implemented in June 2008. WMO numbers have to be obtained BEFORE deployment. When using BUFR, the letter Q is not being used as it is not part of the WMO number.
   

(see also the WMO number page)