Manual on Codes International Codes Volume I.1 Annex II to the WMO Technical Regulations Part A – Alphanumeric Codes. 2011 edition, Updated in 2017,

Abstract

Volume I of the Manual on Codes contains WMO international codes for meteorological data and other geophysical data relating to meteorology; it constitutes Annex II to the Technical Regulations (WMONo. 49) and has therefore the status of a Technical Regulation. It is issued in three volumes: Volume I.1, containing Part A; Volume I.2, containing Part B and Part C; and Volume I.3 containing Part D. Coded messages are used for the international exchange of meteorological information comprising observational data provided by the World Weather Watch (WWW) Global Observing System and processed data provided by the WWW Global Data-processing and Forecasting System. Coded messages are also used for the international exchange of observed and processed data required in specific applications of meteorology to various human activities and for exchanges of information related to meteorology. The codes are composed of a set of CODE FORMS and BINARY CODES made up of SYMBOLIC LETTERS (or groups of letters) representing meteorological or, as the case may be, other geophysical elements. In messages, these symbolic letters (or groups of letters) are transcribed into figures indicating the value or the state of the elements described. SPECIFICATIONS have been defined for the various symbolic letters to permit their transcription into figures. In some cases, the specification of the symbolic letter is sufficient to permit a direct transcription into figures. In other cases, it requires the use of CODE FIGURES, the specifications of which are given in CODE TABLES. Furthermore, a certain number of SYMBOLIC WORDS and SYMBOLIC FIGURE GROUPS have been developed for use as code names, code words, symbolic prefixes or indicator groups.