metaf2xml: parse and decode METAR, TAF, SYNOP and BUOY and write data as XML

(deutsche Version, versión en Español)

metaf2xml parses and decodes aviation routine weather reports (METAR, SPECI), aerodrome forecasts (TAF), synoptic observations (SYNOP) and observations from buoys (BUOY). The extracted data can be written as XML or passed to a user-defined function (all done in Perl).

It also provides XSLT style sheets to convert the XML to plain language (text, HTML), or XML with different schemas. A web-based (CGI) user interface can be used to fetch and display current weather data from NOAA, Ogimet, and other sources.

Content	Screenshots
Latest version Background Why another METAR/TAF parser? Features of metaf2xml Demo version on SourceForge Useful links Examples for messages in plain language	TAF SBGL (HTML, español)	METAR KJFK (HTML, english)	METAR UUEE (HTML, Русский)

Latest version

The latest version (2012-04-18) is 1.48 (TAR, RPM, ZIP), and includes also README, change log, ToDo, distinfo, and DTD.

Background

METAR and SPECI (weather observation) and TAF (weather forecast) information is essential for flight planning and in-flight decisions (real flight and simulation). It is regularily compiled by meteorologists at about 3500 airports worldwide and distributed via reliable, non-public networks. Information for SYNOP is collected by more than 11 000 manned and unmanned meteorological stations around the world and is used for weather forecasting and climatic statistics. The format of the original messages is abbreviated, some items are coded. Here are some METAR, TAF, and SYNOP messages from Rio (SBGL, 83746), New York (KJFK, 74486), and Tokyo (RJTT, 47662) and BUOY messages from a buoy nearby (31743, 41595, 53524):

SBGL 180600Z 00000KT 9999 FEW008 22/20 Q1018
KJFK 180551Z 36016KT 10SM BKN250 16/M01 A3016
KJFK 180831Z 1809/1912 01012KT P6SM BKN120 FM181600 VRB05KT P6SM BKN150 FM181900
 18011KT P6SM BKN150 FM182300 18008KT P6SM BKN100 FM190200 16005KT P6SM BKN100
RJTT 180630Z 09010KT 9999 FEW025 18/11 Q1016 NOSIG RMK 2CU025 A3002
RJTT 180840Z 1809/1912 10010KT 9999 FEW015 SCT030 BECMG 1811/1813 04013KT BECMG 1900/1903 08008KT
AAXX 18064 74486 NIL
AAXX 18064 47662 12/70 30606 10195 20066 30127 40170 56008 60001 83200
ZZYY 41595 18042 0540/ 729282 042978 6112/ 11119 30227 40227 52247 22219 00214 444
 20120 18042 0449/ 50101 80100 80017 9/015
ZZYY 53524 18042 0559/ 126760 145932 6112/ 22219 00197 444 20120 18042 0546/ 50101 80028 80014 9/015

The format of the messages (and a lot more about observing and reporting weather) is specified in WMO Manual No. 306 or in Annex 3 to the Convention on International Civil Aviation; some countries deviate from that standard or extend it, some have published documentation (e.g. Federal Meteorological Handbook No. 1 and No. 2 for the USA). Especially the format of the remarks for METAR and TAF messages, or the coding of sections 3 and 5 for SYNOP messages depend on the country or even the observing station.

metaf2xml can be used for flight simulations or by private pilot (students) who want to extend their knowledge about the message formats, and everyone who just wants to know the current or forecast weather at some station in plain language (see examples below).

Why another METAR/TAF parser?

There are other projects that deal with METAR and TAF messages, e.g.:

• the program "metar" of the FlightGear project,
• the Perl module Geo::METAR,
• the Java library jweather,
• the C library MDSP from the NOAA/NWS (link to download seems to be broken, on SourceForge: mdsplib),
• an MS Windows binary (runs with Wine) in a ZIP archive from MetarWeather,
• the ADDS department of the NOAA translates METAR and TAF messages (most elements) from their database,
• the web site Ogimet provides graphical and text-based interfaces to up-to-date and older METAR, TAF, SYNOP and BUOY data (collected from NOAA),
• the web site mundomanz provides graphical and text-based interfaces to up-to-date and older SYNOP data; most parts of the messages are also translated to plain language (English, Spanish),
• the web site Landings: Aviation's Databases fetches current weather messages (source: NOAA/IWS) and can display them in plain language (enter the airport code or name and follow the link for the decoded METAR or TAF),
• Allmetsat provides a graphical interface to METAR and TAF data (source: NOAA/IWS); the most relevant parts of the messages are also translated to plain language.

But somehow I always missed a feature I liked to have.

Features of metaf2xml

processing of messages

The parser module (man page) accepts (= processes) or tolerates (= marks as error) many extensions to the standard; they are marked with "EXTENSION" in the source code. Many common minor errors in the format are corrected before parsing, more combinations of weather phenomenons are allowed, missing information is recognised in many cases, too.
All remarks are processed, some of them are interpreted depending on the issuing country or station, e.g. 'MON INVIS VAL FOSCHIA' and QUL/QUK (Italy), 'JP' (some carribean countries), 'YLO1' (military), everything from the Federal Meteorological Handbook No. 1 and the Air Force Manual 15-111 (19.12.2003), 'RSNK' and 'LAG PK' (data from other observing stations), and many more. Currently, more than 80 types of METAR remarks are recognised, excluding trivial keywords (see also the DTD).
The intention is to gain as much information as possible from a message without interpreting parts of it wrongly.

output of message data

The module XML.pm (man page) can write the data as XML. Alternatively, this module can be used to register a callback function which is passed step by step the same data in the same order as for the XML output.
The data contains solely information from the original message, with 2 exceptions: the relative humidity (actually 4 different values from 4 different formulas) and the ceiling (if there is one); these 2 items are cumbersome to compute with XSLT. For each data element, the corresponding text from the message is provided.
The intention is that no parsing of the output data should be necessary.

source of messages

Messages can be specified simply as text. Additionally, the script metaf.pl (man page) can be used from the command line or as CGI script to fetch up-to-date messages for airports (METAR/TAF) and stations (SYNOP, BUOY) from a public server or read messages from a local file.
metaf.pl uses the module src2raw.pm (man page) to extract correctly formatted messages from the files provided by public servers.

display of XML file

The project also provides XSLT style sheets to convert the XML to plain language as text or HTML in English, German, Spanish, and Russian (corrections and additions are welcome). The output in the text format is similar to the one of the program "metar" from the FlightGear project. The HTML output displays each message in a separate table. The leftmost column contains the original text for each element of the message, the top row contains the original message (see also project screenshots or examples below). To convert the content to text or HTML, the program "xsltproc" is used, but others that work similar shouldn't be a problem.
There are also XSLT style sheets to create a summary or overview: only some items of each message (currently no TAF) are shown in an abbreviated format, one line per message.

command line interface

The script metaf2xml.pl (man page) reads messages, processes them, and writes the XML data to standard output. It can serve as input for "xsltproc" or similar programs to get HTML or text.
The script metaf.pl (man page) can be used to fetch up-to-date messages from other sources.

web interface

Ideally, any XML capable browser should be able to process the XML with the XSLT style sheet specified in the file, and display the formatted result, but not all browsers are XML capable. The script metaf.pl (man page) provides an interface using either XML/XSLT or pure HTML. The XML data can be seen by viewing the source of the web page if "XML" was selected as output format.

source code is available and GPL

Everybody who wants to contribute is invited to do so. If you want to help you might pick a task from the ToDo.

Demo version on SourceForge

With the demo version with graphics (uses Ajax), the stations are marked with a dot on a map. The map can be viewed in different enlargements and can be moved by click and drag. The processed messages are displayed beneath the map, with the latest request on top. The list of stations is fixed but it also could be created dynamically, e.g. from a database.

The messages for the stations are fetched from files on the SourceForge server. These are messages from the past, the files are updated manually from time to time, only. SourceForge does not allow outgoing connections, so messages cannot be fetched directly from the internet.

With the text-based demo version, weather messages can be entered. If the option "ICAO id(s)" or "WMO id(s)" is selected, station id's can be entered, too. The messages for the stations will be fetched from files on the SourceForge server, as for the graphical demo version.

Several organisations and providers offer public access to up-to-date and older weather messages, e.g.:

• the ADDS department of the NOAA (36 hours of METAR, latest TAF),
• their experimental dataserver (72 hours of METAR and TAF, as XML or CSV),
• Nav Canada (Canada, only),
• Ogimet (METAR since 2005, TAF since 2006, SYNOP and BUOY since 1999),
• the NWS department of the NOAA (24 hours of METAR, TAF, SYNOP and BUOY),
• the College of DuPage (5 days of SYNOP but for fewer stations).

Useful links

demo version

(see also Demo version on SourceForge)

• demo version with graphics
• text-based demo version

files from the latest version

• the README
• the ChangeLog
• the document type definition (DTD) for the XML data

man pages (generated from the perl sources)

• for the parser module parser.pm
• for the module XML.pm to write the XML
• for the module src2raw.pm to extract messages from the files provided by public servers
• for the script metaf2xml.pl
• for the script metafsrc2raw.pl
• for the (CGI) script metaf.pl

project links

• the project at SourceForge: summary, packages for releases, news, web access to the Git repository
• the project at freecode

Examples for messages in plain language

The result of the parsing of the above example messages can be found in example.xml (XML without XSLT style sheet reference). Using the XSLT style sheets from the project, the output in plain language (here: as HTML, summary first, then detailed) looks as follows:

Warning: The information below may be out-dated, inaccurate, or both. It is not suited for use in aviation.

Warning: The information below may be out-dated, inaccurate, or both. It is not suited for use in aviation.

Values of entries marked with * do not originate directly from the message, but are derived from its data.

warning: not processed: 18042 0449/ 50101 80100 80017 9/015

warning: not processed: 18042 0546/ 50101 80028 80014 9/015

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