INTERNATIONAL RADIO WEATHER CODE 



FOR USE ON UNITED STATES SELECTED SHIPS 



1 . This code book is for use of observers in the coding of weather observations from ships that are specially 

 selected for international service and designated SELECTED SHIPS. 



2. Other ships reporting to the United States Weather Bureau will continue to use the word code as con- 

 tained in W. B. No. 860 — Radio Weather Code for Vessel Weather Observers, 1925. 



3. Figures, in groups of five, are employed exclusively in the code described herein. The code was adopted 

 by the International Meteorological Organization at a conference held at Copenhagen, Denmark, in September, 

 1929, and will be used by SELECTED SHIPS of all nations. 



4. A marked advantage of the code is that when it goes into general use, certainty of translation, regardless 

 of the nationality of the ship from which a weather report is sent, is assured. The code tables and explanations 

 herein will also, be useful to vessel masters in decoding weather reports received from ships employing this code. 



DESCRIPTION OF CODE 



5. The first four groups, designated as the UNIVERSAL DATA, invariably will be the same. Additional 

 data may be included but they are restricted to a choice from two combinations, designated Supplemental Data. 

 Only one of the Supplemental Data combinations may be used in the same message with the UNIVERSAL 

 DATA and then in the prescribed arrangement and order. The first figure of the Supplemental Data always 

 identifies the combination code that is being used. 



6. For convenience in preparing observations and coding the radiograms, each item of data is given a dis- 

 tinctive symbol. The symbols and group arrangements are as follows: 



Universal Data: PQLLL 111GG DDFww BBVTT. 



Supplemental Data: GKdCN t d d B AWC H . 



(The identifying figure for this combination of groups is always the figure 6.) 



Supplemental Data: 3C L C M C H N t d KdWN L d a fabb. 



(The identifying figure for this combination of groups is always the figure 3.) 



7. Each ship will be given separate instructions in writing or otherwise should Supplemental Data be desired. 

 In the absence of such instructions only the UNIVERSAL DATA will be coded and included in the radiogram. 



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