RESTRICTED 



above normal for a period oi' twenty minutes. It was preceded 

 and follov/ed by tv/e'lve hours of unusually hich sciciies, liiany 

 of tlierd exceeding one foot, with periods of 13 to I5 ininutes. 



Siaall lagoon seiches of periods somewhat longer than one 

 hour and heights up to u.2 foot have been recorded frequently. 

 They are of no ii.iportance in evaluating the circulation of the 

 lagoon. 



According to HO iiisc. 11275, the waves generated inside the 

 lagoon should be I.5 feet high at the anchorage area, 2.5 feet 

 in the middle of the lagoon, and 3,5 feet at the v/estern end 

 with an IS knot wind. V/ith a 10 knot wind they should be re- 

 spectively 1 foot, 1.5 feet, and 2 feet. The periods should be 

 between 2 and 3 seconds. These values agree v/ith observations. 



The trade winds give rise to large breakers on the exposed 

 eastern and northeastern reefs. With an IS knot wind, the break- 

 ers v/ere foiind to be about 10 feet high. If the winds decrease 

 din-ing the sumiaer, these waves will becone smaller, and should 

 be about 4 feet high with a 12 knot wind. 



A swell recording unit has been in operation inside the 

 lagoon near Bikini Island, which has shovm the existence of 

 swell about a. foot high and v/ith a period of 9 seconds. Al- 

 though generally too small to be noticeable from large ships 

 at anchor, it breaks sharply against shore on the lagoon side 

 of the reef. It is believed that this swell is not related to 

 the v;aves generated by the trade wind, since the period differs 

 and since the bottom drops off too steeply off Enjoi for the 

 waves to be refracted inside. They are believed to have coiie 

 through the channel from the south and to have been generated 

 in the southern hendspher e . During July and August, the winter 

 season in the southern hemisphere, they may be as high as five 

 feet in the target area. 



2.23 Meteorology 



Table 2 is a smimarj'- of meteorological observations obtained 

 during the present investigation, and Figures 1 and 2 show daily 

 wind averages and the diurnal variation in v/ind speed. It is 



Table 2. Vifeather observations from Bikini 



