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Weather Station Identifiers

Identifiers are an important building block in meteorology because they provide a scheme which identifies the various weather stations in use. To accurately use weather data, meteorologists and climatologists have a vested interest in the identifiers used by weather stations. Unfortunately the system is not as simple as it should be. Not only are newer identifiers are constantly coming online, being modified, or made obsolete, but identifiers are sometimes brought into use without coordination between agencies. This is a major problem for those of us who are exchanging weather information in our increasingly globalized world. This resource is intended to help meteorologists maintain accurate station listings.

1. Identifier schemes

a. International Civil Aviation Organization (ICAO) Location Indicator. The ICAO location indicator consists of 4-letter identifiers approved for use under the International Civil Aviation Administration plan of identifiers. In our LIL list, WSR-88D radars are not permitted to have an ICAO code, because this causes conflicts. For example, KGRK is frequently used for both the aerodrome and the radome, which are in fact separated by 35 miles. The ICAO charges between $180 and $920 for direct access to its ICAO identifier assignments.

b. World Meteorological Organization (WMO) identifier. The WMO identifier relies on a 5-digit numeric code to identify a weather station. It is widely used in synoptic and upper air reports. The entire identifier is often called the "index number". The first two digits are sometimes referred to as the "block number" and refer to the geographic area (00-29 Europe, 30-59 Asia, 60-68 Africa, 69 special use, 70-79 North America, 80-89 South America, 90-99 Oceania). The last three digits are loosely referred to as the "station number" in the context of "block numbers". The WMO provides free access to its WMO identifier assignments.

c. Weather Bureau Army Navy (WBAN) identifier. A WBAN identifier is a 5-digit identifier developed in the 1950s to augment the early systems of longline identifiers. It is still used by NCDC to identify many of its climatological datasets and thus continues to be very important for meteorological work. Note that this is not the same thing as the WMO identifier, and in no case are the two equal. NCDC provides free access to its WBAN identifier assignments.

d. Federal Aviation Administration (FAA) Identifiers. The FAA identifier is a three-digit (sometimes 4-digit alphanumeric) designator that was used throughout North America starting in 1964. This identifier was discontinued for meteorological purposes in 1996, but is still used today for aeronautical purposes. In many cases, a three-digit identifier can be "converted" to its ICAO form by adding the appropriate ICAO region letter as the first letter. However this is NOT a reliable rule, especially in Alaska and Hawaii. While ANC may translate correctly to PANC, there are many stations where this is not the case, such as BRW, which is PABR under the ICAO form. This is a significant source of errors in some crossreference tables. An example of an FAA identifier is "DFW" for Dallas-Fort Worth International Airport. The FAA provides direct access to its FAA identifier assignments but does not publish locations except in its National Flight Database (NFD), which costs about $180. This data however is published in webpage form on the privately-operated airnav.com website.

e. International Air Transport Association Identifier. The FAA identifier is a three-digit (sometimes 4-digit alphanumeric) designator that was used throughout North America from around 1964 to 1996. In many cases, a three-digit identifier can be "converted" to its ICAO form by adding the appropriate ICAO region letter as the first letter. The IATA charges $346 and $1100 for direct access to its IATA identifier assignments.

f. Master Station Library (MASLIB) Catalog Number. This scheme, developed by Air Force Global Weather Center (AFGWC), now part of Air Force Weather Agency (AFWA), is perhaps the most comprehensive reference system for weather stations and airports, using a 6-digit number partly based on the WMO code or that of neighboring stations. The LIL does not use the MASLIB code since it is only used internally within AFWA and since not all stations have a MASLIB number.

2. Problems with crossreferencing.

Identifier re-use. Identifiers are occasionally retired and then used again for a different location.

Poor documentation. There are deficiencies in the station lists caused by poorly documented station locations. In the United States, this is a problem with offshore oil platforms, with data for some location identifiers not known.

Identifier moves. The government sometimes creates messy problems by "moving" an identifier to a different locations. This has happened with the move of DEN from Stapleton Airport to the International Airport in 1996, and AUS from Austin Mueller Airport to Bergstrom Airport in 1999. It creates discontinuity in climatological and meteorological records and may create inaccuracies with historical datasets. This was one of our reasons for developing the LIL database.

Oil platforms. Within NOAA and the FAA, there tends to be poor documentation of identifiers used on offshore oil platforms.

KQ identifiers. The KQ-- ICAO identifier block is reserved by the U.S. Department of Defense for special use. Some of the identifiers have been assigned for routine use and their information is known (such as KQCU for Fort Chaffee and KQWS for Fort Drum; many are listed in this source). Other identifiers are used for (1) classified operating locations and (2) for deployed combat weather teams. Their association with a geographic location is usually classified or marked for official use only.

Weather stations are not necessarily at airports, particularly in countries like the former USSR which have often housed observing facilities at towns and government facilities. So in some cases identifiers are erroneously placed at the nearest airfield. On the other hand, some of the "guessed" locations in older MASLIB sources are based on locations of towns in atlases, and may not represent the actual location.

3. Resources

Resource	ICAO	FAA	WMO	WBAN	Special	Coordinates
AUTHORITATIVE SOURCES
WMO Pub 9 A This is the sole, authoritative source of synoptic identifier numbers. Thankfully the WMO does a great job of putting its publications online, and this up-to-date resource can be consulted for all the synoptic identifiers that might be encountered. A flatfile (HUGE) may be obtained here (pick the latest Pub9volA).
Location Indicators, ICAO Publication 7910 (ordering info only) is the sole authoritative source for worldwide ICAO identifiers. Unfortunately the ICAO does a poor job diffusing this information online and charges phenomenal costs for the information.
Location Identifiers, FAA Publication FAAO 7350 is the sole, authoritative source for ICAO identifiers in the United States, where it overrides ICAO Pub 7910. It includes non-authoritative information about Canadian ICAO identifiers. Although 7350.7 is fully online, position information is not available in either the online or printed version.
Canadian METSTAT Tables are the sole authoritative source of all Canadian identifiers. Abbrevations include A=Airport; RCS=Reference Climate Station; CDA=Canada Department of Agriculture; AGDM=Agricultural Drought Monitoring Station; LWIS=Limited Weather Information System.
Australian Bureau of Meteorology Station List Files is the sole authoritative source of Australia's station identifier information online. Data files are organized in both alphabetical and station number order, for the whole of Australia, and by individual states. (Thanks to Peter Creswick)
DERIVED GOVERNMENT SOURCES
US Air Force Master Station Catalog (MASLIB). The MASLIB catalog has for decades been one of the most exhaustive listings of all identifiers. It does contain some errors here and there, and unfortunately is no longer available presumably due to post-9/11 security issues. Archived versions are posted here, obtained from UCAR datasets: 1967, 1973, 1976, 1994, 1995, 1996, 1997, 1998, 1999.
NOTAMS ICAO lookup provides ICAO information. Since it is approved for navigational use, presumably this listing reflects the latest data in ICAO Pub. 7910. It does appear to contain the newest airports around the world. Note that "LOC ID" in this database is equivalent to the FAA location ID. But as is common with authoritative ICAO data, there's no coordinates.
NCDC Station Locator is a good source of U.S. station information, but it seems to be running about 2 years behind on updates as it misses a lot of the ASOS stations; I have also noticed a few errors here and there. The raw station inventories can be found here (raw directory listing), along with a massive station history flatfile called MASTER-STN-HIST.TXT (32 MB). (Due to size, archive copy is not kept on this server; we will put one online if NCDC ever goes down).	USA	USA	USA	USA	USA	USA
NCDC Multinetwork Metadata List is another decent government source that includes WBAN numbers. It seems to lack a lot of the newer ASOS stations and may have originated from the same database as NCDC Station Locator.	USA	USA	USA	USA	USA	USA
NOAA's Platform Name list is helpful for making sense of offshore identifiers.
NWS/TG Table contains thorough listings but from unknown sources and for an unknown purpose. (Also see table with K--- identifiers sorted by identifier).
NWS Meteorological Station Information Lookup is the National Weather Service's "public" station database. While the interface is promising, its data is outdated and it does not contain many of the newer ASOS sites. This is probably simply a web interface for the flatfile above (NSD.TXT).
Greg Thompson (NCAR/RAP) Station Table is very good and updated often! It is a must-see. An older version is mirrored at the FAA ADDS Weather site. Note that there is no provision for older stations and it appears that the distinction is blurred between FAA and IATA identifiers.
NWS Data Review Group processes and archives Requests for Change to its various datastreams (NWSTG, NOAAPORT, FOS, NWWS, AWIPS, AFOS). Identifier changes can sometimes be found in these documents. (AS OF 2009 THIS APPEARS TO HAVE BEEN PASSWORD PROTECTED)
NWS Systems Operations Center Change Notices are another source for finding new identifiers by combing through datastream changes to the NWSTG system.
METEO France is another exhaustive database of stations (no position info). A backup copy (dated 8 Jan 1999, retrieved 25 May 2009) is archived here.	OLD		OLD
ECCAIRS Location Indicators list by the European Coordination Centre for Accident and Incident Reporting Systems appears to be an authoritative derivation of ICAO Pub 7910 and thus provides a valuable supplementary source of ICAO identifiers. Unfortunately it has not been updated since January 2006. An archival copy is made available here.	OLD					OLD
EUROCONTROL used to maintain a current ICAO reference list at this link. However their page states "in December 2007, we have now closed the public access to the tool for searching ICAO 7910 location indicators and their location names. We hope that you have had the time to prepare for an alternative procedure for consulting these codes."	CANX
Digital Aeronautical Flight Information File (DAFIF) is produced by the United States government as a comprehensive navigational database approved for flight operations. This provides information on many ICAO and FAA identifiers. Unfortunately its producers, the National Geospatial-Intelligence Agency, withdrew the product from public access citing intellectual property issues. Data from DAFIF still makes up the vast majority of international identifier information on aviation websites.	CANX	CANX				CANX
NAV CANADA's TAF Interface is about the only "official" source of Canada's METAR identifier information online. This is a crude way of obtaining a few of some of the more obscure ones.	CANADA
Environment Canada's Synoptic Station List shows synoptic identifiers within Canada, in WMO Pub 9 A format (thanks to Christine Hudnall for finding the new version). A backup copy (dated May 2009, retrieved 25 May 2009) is archived here.
British Atmospheric Data Centre Historical International Station Catalogue Historical International Station Catalogue - This index is somewhat outdated and similar to the MASLIB, but due to the historical slant I have found this useful for researching identifier changes, especially outside the U.S. It can be used in conjunction with a similar NCDC product. A backup copy (dated 3 Nov 1998, retrieved 25 May 2009) is archived here (1.8 MB).
British Atmospheric Data Centre Historical International Station Catalogue Historical International Station Catalogue - This index is somewhat outdated and similar to the MASLIB, but due to the historical slant I have found this useful for researching identifier changes, especially outside the U.S. It can be used in conjunction with a similar NCDC product. A backup copy (dated 3 Nov 1998, retrieved 25 May 2009) is archived here (1.8 MB).
OTHER SOURCES
Philip Gladstone's CWOP - This I have found useful for researching is pretty thorough and has many different weather databases crossreferenced. You can also check this list. The problems with this list is it omits various WMO and WBAN identifiers and does not have historical identifier information.
AIRNAV is a high-traffic aviation website that is useful for finding exact information about any airfield. It has been of use for finding new airfields with obscure ICAO / FAA identifiers.
World Aero Data is another good aviation identifier site. It appears it draws mostly on the withdrawn DAFIF product.
OpenFlights is a collaborative attempt to pick up where DAFIF left off. One problem with this project is the blurring of IATA and FAA identifiers, which in meteorological use can cause numerous conflicts with historical data.

4. Other investigation resources.

COUNTRY CODES. This interface to geonames.org determines which country a given lat/long is in.

TIME ZONES. To find the time zone used by a particular station, we recommend using the geonames.org database. Here is a convenient form for requesting data.

ELEVATION. This interface to geonames.org queries the SRTM (Shuttle Radar Topographic Mission) and returns an elevation in meters. However we've found that the Google Earth elevation readout gives considerably more accurate results, at least in the U.S. and Canada.

5. Miscellaneous

LatLonToElevation allows fast calculation of unknown elevations using the National Elevation Dataset and Shuttle Radar Topography Mission.

METAR Maintenance, a short page by Joe Wakefield, describes what is involved in updating AWIPS with new stations.

6. Software

METAR Audit is a small utility developed by us. It will look at a DIGATMOS.STN station listing and a file with METAR observations and find any METAR reports that do not appear in the station listing. This is a good way to detect new reporting stations. METAR Audit is a 140K download and requires PKUNZIP or WinZip -- note that this is only for experienced users and we will not provide any technical or installation support. However we would be happy to hear about any new entries you have made to your DIGATMOS.STN file. It should be noted that Digital Atmosphere V2.06 and later (May 2009) has built in auditing capability, negating the need for this utility.