RESTRICI^D 



11 



The oppocite extreme is the water near the southv/estern 

 passes, v/hero horizontal salinity gradients of 0.10°/oo per ::iile 

 indicate rapid uixing with v/ater froui outside. Collections laade 

 here at different phases of the tide shov/ that the isohalines 

 drift one to t\YO niles during a tidal cycle. 



The presence of a tongue of high salinity water extending 

 from the central part of the lagoon toward Enyu Channel is indi- 

 cative of a coiaplicated current pattern in this part of the la- 

 goon. It is of little practical significance and therefore has 

 not been studied in detail, but there is little doubt that one 

 or more eddies exist between the saline central v/ater and the 

 fresher waller to the south. 



The salinities in the southeastern part of the lagoon ad- 

 jacent to Enyu Channel are of some help in clarifying the rather 

 obscure results of the current measureiiients. The latter show 

 that there is continuous outflov; froi.i this area through the west- 

 ern third of Enyu Channel and from the southv/estern passes by 

 way of a narrow band of current just inside the southern reefs. 

 Obvious sources of flow into the area are the eastern part of 

 Enyu Channel, the eastern reefs, and the main body of lagoon 

 water to the north and west. The salinity distribution indicates 

 that of these possible sources, Enyu Channel is the most iiapor- 

 tant. The expansion and contraction of the 34.75 Isohaline 

 proves the existence of tidal interchange. The curvature of all 

 the isohalines demonstrates the presence of an eddy centered 

 soTiiewhere near the middle of the reef in Enyu Channel, such that 

 water flows in through the eastern part of the channel and out- 

 ward on the western side. 



Study of temperature distribution has added nothing to -^"^^ 

 general picture of current patterns. Diurnal temperature v 

 tions are of a large enough magnitude so that a p^. '-"ular ■; 

 mass cannot retain identifiable temperature characttj.^ 

 long. Therefore the observations can be used only for study: ng 

 rapid mixing processes between water masses of pronounced char- 

 acteristics, such as inflov/ near the reefs. 



3.22 Vertical variations in teiaperature and chemical 

 constituents 



Vertical variations arise in two ways: (a) by horizontal 

 movements of water masses having different characteristics, and 

 (b) by diurnal changes. 



One of the best examples of the first type is founa near 

 the reefs where the incoming water is warmer during the daytirae 



