northeast fetch; about 10 percent of the waves are > 1.5 meters as compared to 60 percent 

 in the northwest corner (Fig. 45). High seas, 3.7 meters or greater, occur less frequently in 

 the southwest than throughout most of the northern section. They occur generally less than 

 2 percent of the time but approach 10 percent in two quadrats (10° to 20°N, 120° to 

 130°W and 20° to 30°N, 130° to 140°W). Summer gives the most northerly advance of the 

 southeast trades, to 10°N. Frequency of 1.5-meter or greater seas varies from a maximum 

 of about 45 percent in the northwest to a minimum of 15 percent in the southeast. Seas of 

 3.7 meters are rare in the 20° to 30°N region but are slightly more common in the 10° to 

 20°N region due to the tropical cyclones (Fig. 46) which occasionally occur in that region. 



In summary, sea states are generally higher at points further from the coast (west) 

 and at the higher latitudes (north). Fall and winter show the highest seas, and summer is the 

 calmest season except for occasional tropical cyclones through the southeastern section. 



Summary of Meteorological Data 



Wind and wave data for the survey area were requested from the Naval Weather 

 Service Detachment, National Climatic Center, Asheville, North Carolina. Table 4 is a sum- 

 mary of these data and presents monthly mean and 99.5 percentile wind speeds and wave 

 heights, the percentile of 18 m/sec winds, and an annual wave period distribution. Events of 

 99.5 percentile indicate that 0.5 percent of the time (3.5 hours/month), during any given 

 month, the event will occur at or greater than the level indicated. The areas of the meteoro- 

 logical survey are shown in Fig. 47. The areas delineated are equivalent to those oceano- 

 graphic survey quadrats in Fig. 1 as indicated by the number in the lower right hand corner 

 of each area. Areas 5 and 6 have the lowest mean wind velocities (3 to 5 m/sec in winter 

 and 4 to 6 m/sec in summer) and have maximum wind velocities during summer of 1 9 and 1 4 

 m/sec, respectively. Area 5 is subject to tropical cyclones during late summer and early fall, 

 which explains the elevated summer velocities. Area 4 has the highest mean (6-8 m/sec) and 

 99.5 percentile (19-26 m/sec) wind velocities. This represents the area north of Point Con- 

 ception to 45°N. The high winter maximums (23-26 m/sec) represent the southerly exten- 

 sion of extratropical cyclones. Areas 1, 2, and 3 are similar, averaging between 5 and 8 

 m/sec winds with maximum winds (99.5 percent) varying between 13 and 18 m/sec. These 

 winds are relatively constant because they are in the northeast trade wind zone. 



Mean wave heights are rather constant in all the areas surveyed varying between 1 

 and 1 .5 meters. Maximum waves vary significantly; the highest seas are in the north (area 4, 

 varying between 4.5 meters in the summer and 8 meters in January) and in the west (4 to 

 7.5 meters), due to the long fetch of the northeast trades. All the other areas have lower 

 maximum sea states which vary between 3 and 5 meters at the 99.5-percent level. 



26 



