ICG-WIGOS-3/Doc.4.2(2) p. 1

World Meteorological Organization / ICG-WIGOS-3/Doc.4.2(2)_Rev.1
INTER-COMMISSION COORDINATION GROUP ON WIGOS (ICG-WIGOS-3) / Submitted by: / Secretariat
Date: / 5.2.2014
THIRD SESSION
GENEVA, SWITZERLAND
10 – 14FEBRUARY 2014 / Original Language: / English
Agenda Item: / 4.2

WIGOS Station Identifiers

Action requested of ICG-WIGOS

  1. Agree principles for station identifiers for use in WIGOS.
  2. Agree the structure for WIGOS station identifiers.

Background

  1. A station identifier system has two main purposes. The identifiers can be used to locate time series of observations, and they allow metadata to be associated with an observation.
  2. Traditional surface synoptic observations over land reported in SYNOP code use the station identifier to link the observation to the location, height and operating characteristics of the station so that these elements did to be included in the message. These identifiers use a station identifier of the form IIiii, where II is the “block number” (this refers to an area of the globe) and iii is the station number within the block. In many regions of the world, there are no more identifiers available. A new system of station identifiers is needed.
  3. Different observing networks have used different systems for allocating identifiers. In some cases (such as when drifting buoys were allocated five digit identifiers) the same identification characters have been issued to different stations at the same time. Even for synoptic stations, the same IIiii can be issued to surface and upper air stations at different locations. As WIGOS brings together observations from sources that did not interact before, ambiguity in the station identifiers will be a source of errors.
  4. This paper outlines a system of station identifiers for use in WIGOS that can (if used correctly) guarantee that the same identifier is not allocated to more than one station, and that allows current identifiers to be assigned within the system so that when the identifiers are used in their local context the traditional form of the identifier can be retained.
  5. If ICG-WIGOS agrees the approach outlined in this paper, detailed work will need to be done by IPET-DRMM and IPET-MDRD allow the WIGOS station identifier to be recorded Table Driven Code Forms and other data representations, and by each observing programme will need to define how its existing identifiers will be mapped onto the WIGOS identifier. The WIGOS station identifiers will also provide a tool to allow WIGOS metadata records to relate observations to observing stations.

Principles

  1. WIGOS would benefit from a single system of identifying stations and platforms so that these can be referred to unambiguously for the purpose of linking information associated with the stations and platforms.
  2. The following principles should apply to WIGOS station identifiers (in this context, the word “station” refers to stations, platforms, satellites and related concepts):
  • There should be no implicit meaning in the WIGOS identifier (that is, the identifier should provide no information about the station, the types of observation it issues, the management of the station or any other aspect of the observations or station).
  • Station identifiers should be unique (that is, a single station identifier cannot refer to more than one physical station; for example, if a land station moves it should be issued with a new station number).
  • The system for identifying stations in WIGOS should be applicable to all observing systems.
  • The system for identifying stations in WIGOS should be extensible so that it is not necessary to issue new identifiers for existing stations if requirements change in the future.
  • The system used for WIGOS identifiers should be capable of incorporating existing station identifiers in a way that allows the existing identifiers to continue to be used as a short-hand within the communities already using them (to avoid an extensive software replacement programme).
  • All stations that contribute observations to WIGOS must have a WIGOS station identifier.

Proposed system for WIGOS station identifiers

  1. The proposed structure of a WIGOS station identifier is shown Figure 1.

WIGOS Identifier series / Issuer of Identifier / Issue Number / Local Identifier

Figure 1. Structure of WIGOS station identifier

  1. The use of the parts for the WIGOS station identifier is given in Table 1.

Table 1. Meaning of the component parts of a WIGOS station identifier.

WIGOS Identifier Series / This is used to distinguish between different systems for allocating identifiers. It is primarily to allow future expansion of the system so that stations do not have to be issued with new identifiers. Its value is 0 (zero).
Permitted range: 0-3
Issuer of Identifier / A number that is used to distinguish between identifiers issued by different organizations
Permitted range: 0-1023
Issue Number / A number that an organization responsible for issuing an identifier may use to ensure global uniqueness of its identifiers. For example, allocating one issue number for hydrological stations and another for voluntary climate observing stations would enable the managers of the two networks to issue Local Identifiers independently without needing to check with each other that they were not duplicating identifiers.
Permitted range: 0-1023
Local Identifier / This is the individual identifier issued for each station. An organization issuing identifiers must ensure that the combination of Issue Number and Local Identifier is unique; in that way global uniqueness is guaranteed.
New Local Identifiers generated under the auspices of WIGOS consist only of the digits 0-9.
Local Identifiers that are created from pre-existing station identifiers may contain a mixture of numbers and letters.
Permitted ranges:
New Local Identifiers created under the WIGOS scheme: 0-999,999
Existing identifiers transferred to Local Identifiers: 10 characters.

Note: although the table proposes initial ranges of permitted values of the components that make up aWIGOS station identifier, future changes in requirements may result in these ranges being increased. IT systems must, therefore, be designed to process identifiers whose components are of arbitrary length.

BUFR encodings will be prepared for WIGOS station identifiers to allow efficient representation of purely numerical Local Identifiers and mixed character Local Identifiers.

The convention for writing the WIGOS identifier is:

WIGOS Identifier series>-<Issuer of Identifier>-<Issue Number>-< Local Identifier

For example, the WIGOS Station Identifier

WIGOS Identifier series
0 / Issuer of Identifier
513 / Issue Number
215 / Local Identifier
5678

would be written as 0-513-215-5678.

Allocation of WIGOS Station Identifiers

  1. Mapping existing WMO station identifiers onto WIGOS station identifiers is an administrative task. Formal procedures are needed to control the issue of new WIGOS station identifiers to ensure that WIGOS station identifiers only refer to a single station.
  2. The WMO Secretariat issues “Issuer of Identifier” numbers to bodies authorized to allocate WIGOS station identifiers by EC on behalf of Congress.
  3. Bodies issuing WIGOS station identifiers must ensure that:
  4. They do not issue any WIGOS station identifier to more than one station
  5. WIGOS observational metadata relevant to stations for which they issue WIGOS station identifiers is made available according to the requirements of the Manual on WIGOS.
  6. WIGOS station identifiers are used solely for identifying stations. They do not imply anything about quality of or responsibility for observations (these aspects are covered by WIGOS observational metadata). Issuers of WIGOS station identifiers are therefore encouraged to issue WIGOS station identifiers to any station that requests an identifier whose operator the issuer of the WIGOS station identifier considers to be competent to maintain the WIGOS observational metadata.

Assigning WIGOS station identifiers to correspond to existing station and platform identifiers

  1. The following approach can be used to incorporate existing WMO identifiers into the WIGOS station identifier system. This can be extended to include identifiers that have been issued by other Programmes or organizations.
  2. The “WIGOS Identifier Series” is 0 (zero).
  3. The “Issuer of Identifier” is used to distinguish between the existing methodologies for issuing station identifiers.
  4. Values for the Issuer of Identifiers from 0-499 are intended to be used to enable existing identifiers to be included in the system. The method of mapping between the existing identifiers and WIGOS station identifiers has to be defined for each of the existing series of identifiers.The guiding principle is that the Local Identifier component of the WIGOS station identifier can be extracted and used by existing software.
  5. Values for the Issuer Identifiers of 500 and above are used to identify organizations that are authorized to issue new WIGOS identifiers. No constraints are placed on how issuers allocate Issue Number and Local Identifier, provided that they issue the same combination no more than once.
  6. Table 2 illustrates how existing station identifiers could be mapped onto WIGOS station identifiers. The table is incomplete, and further work is needed to confirm that the suggested mappings are viable. The intention of providing the table is to illustrate that such mappings are feasible.
  7. Using this method of mapping means that the existing identifier can be extracted simply from the WIGOS station identifier in a pre-processing step when preparing reports and charts, minimizing the impact on existing software.

Table 2. Assigning WIGOS identifier for stations with existing station identifiers.

WIGOS station identifier component:
Existing source of station identifer / Issuer of Identifier / Issue Number / Local Identifier
World Weather Watch land station with SI = 0 / 0 / 0 – station defined in Volume A at the time the WIGOS station identifiers entered into use.
Any other number: used to distinguish between different stations that have used the same IIiii at different times / Use the block number (II) and station number (iii) as a single five digit number IIiii (with leading zeroes)
Example: station 60351 (in Algeria) would be represented by:
0-0-60351
World Weather Watch land station with SI = 1 / 1 / 0 – station defined in Volume A at the time the WIGOS station identifiers entered into use.
Any other number: used to distinguish between different stations that have used the same IIiii at different times / Use the block number (II) and station number (iii) as a single five digit number IIiii (with leading zeroes)
Example: upper air station 57816 (in China) would be represented by:
0-1-0-57816
World Weather Watch data buoy / 2 / 0 – buoy identifier at the time the WIGOS station identifiers entered into use.
Any other number: used to distinguish between different buoys that have used the same buoy identifier at different times / Use the region/buoy number combination
A1bwnbnbnb
Examples: the data buoy 5900191 operated by Korea would be represented by:
0-2-0-5900191
The World Weather Watch list of data buoys lists two buoys with identifier 13001. The buoy in use at the time WIGOS station identifiers were introduced is allocated:
0-2-0-13001
and the second buoy is issued identifier:
0-2-1-13001 (note- the Issue Number is different from that for the first buoy)
Ship Identifier – issued by ITU / 3 / 0 = ship allocated the identifier at the time WIGOS station identifier was introduced
Any other number: used to distinguish between different ships that have used the same ship identifier at different times / Ship identifier
Example: the (now obsolete) weather ship C7R would be represented by:
0-3-0-C7R
Ship Identifier – issued nationally / 4 / 0 = ship allocated the identifier at the time WIGOS station identifier was introduced / Ship identifier
Example: the fictitious ship XY123AB would be represented by:
0-4-0-XY123AB
Aircraft tail number / 5 / 0 = aircraft allocated the identifier at the time WIGOS station identifier was introduced
Any other number: used to distinguish between different aircraft that have used the same aircraft identifier at different times / Aircraft tail number
Example: aircraftEU0246 would be represented by:
0-5-0-EU0246
Etc…