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MANUAL OF MARINE METEOROLOGICAL OBSERVATIONS 



9421. When the directions of the sea and swell waves have been entered 

 in columns 34 and 37 and the wave heights are less than 15 feet, the di- 

 rections will be entered similarly in column 41 for sea and column 45 for 

 swell. 



9421.1. If the wave height for either sea or swell is above 15 feet, 

 50 will be added to the coded wave direction, e.g., the direction of the sea 

 coming from 320° with a height of 20 feet would be entered in column 34 

 as 32 and in column 41 as 82 (32 + 50). 



9430. PERIOD (P^). Enter the period of the sea waves in seconds 

 directly in column 35 and the period of swell waves in column 38. 



9431. Select the code figure from Code Table 17 corresponding to the 

 average sea wave period in column 35 and enter the coded figure in column 42. 



9432. Select the code figures from Code Table 17 corresponding to the 

 average swell wave period in column 38 and enter the coded figure in column 46. 



Code Table 17 

 SYMBOL P^. --Period of waves 



9440. HEIGHT (H^). Enter the height of the sea waves in half meter 

 units directly in column 36 and the height of the swell waves in column 39. 

 That is, for a height of 9 feet (3 meters) there will be 3 x 2 or 6 one-half 

 meter units and the value 6 will be entered in the appropriate column. 

 These correspond to the values found in Code Table 18. 



9441. Select the code value from Code Table 18 corresponding to the 

 average sea wave height and enter it in column 43. 



9442. Select the code value from Code Table 18 corresponding to the 

 average swell wave height and enter it in column 47. 



