INTRODUCTION 



Table 3 gives the salinity corresponding to different values of density 

 at the standard temperature of 15°C. 



The observations are usually made once each weekday at whatever 

 time the observer attends the gage. At some stations situated within or 

 near the entrance of an estuary, the temperature or density varies with 

 the stage of tide or with the direction of the tidal current. It may be 

 assumed that in the course of a month or more the distribution of obser- 

 vations is fairly uniform over all phases of the tide. 



The mean temperature and density curves are derived from the month- 

 ly means given in Table 1 and show graphically the seasonal variation 

 for many places. 



For some practical uses of density data, it is more important to 

 know the density at the temperature apt to be encountered than at the 

 standard temperature. The graph, Sea Water Density at Various Tempera- 

 tures, provides for converting density at 59°F (l5°C) to density at 

 other temperatures. 



The following Coast and Geodetic Survey publications on sea water 

 temperatures, salinities and densities are also available: 



C&GS Publication 31-1 > Surface Water Temperature and Salinity, 

 Atlantic Coast, North and South America (Second Edition) 

 1965, 55 cents. 



C&GS Special Publication No. 298, Sea Water Temperature and 

 Density Reduction Tables, 1953. 25 cents. 



