INTRODUCTION 



The summaries of sea water temperatures and densities presented 

 in this publication are based on observations made at locations along 

 the Atlantic coast of North and South America and adjacent islands 

 through the year 1971. The sea water temperatures and densities were 

 observed primarily at tide stations which, in the United States and 

 possessions, were maintained by the National Ocean Survey, often with 

 the cooperation of other organizations. Pinal results for places in 

 Venezuela were furnished by the Minis terio de Obras Publicas, Republica 

 de Venezuela, For places in other countries, the National Ocean Survey 

 derived the data from observations made by organizations in the particu- 

 lar country. In Latin America, the observations were obtained through 

 the cooperation of the Inter American Geodetic Survey. 



Table 1 presents monthly means and annual means and extremes of 

 the surface water temperatures and densities for each year of obser- 

 vation after 1961].. Earlier observations are combined in five-year 

 groups. For each station at which the series of observations covered 

 two or more years, there are given the following monthly values for 

 the series: the mean of the monthly means, the maximum observed, the 

 mean of the monthly maxima, the mean of the monthly minima and the 

 minimum observed. 



When an asterisk appears in either extreme temperature column in 

 Table 1, it indicates that the extreme may have been exceeded if obser- 

 vations had been available for all months in which the maximum or 

 minimijm normally occurs. If observations are not available for any of 

 the months in which the yearly maximum or minimum may have occurred, 

 the extreme has been omitted. For densities, the yearly extremes are 

 from the months of the year for which means are given. If they are 

 from an incomplete year, they are followed by an asterisk. 



The temperature data given in degrees Celsius are based on ther- 

 mometer readings made in a sample of water drawn by bucket from a foot 

 or two below the surface. They can be converted to degrees Fahrenheit 

 by means of Table 3» 



The density of any substance is defined as the mass per unit volT;ime 

 The density of sea water, as observed, depends not only upon the amount 

 of soluble matter held in solution but also upon the temperature of the 

 water at the time the reading was made. It is necessary, therefore, to 

 reduce the observed densities to densities at a standard temperature in 

 order that they may be comparable. In this publication the standard 

 temperatiire is taken as l5°G (59°F). The density of pure water at a 

 temperatiore of l5°C is taken as 0,9991. The observed densities obtained 

 by means of a hydrometer are reduced by using the tables given in C&GS 

 Special Publication No, 298. 



Densities in Table 1 are expressed in terms of the Greek letter 

 sigma with a subscript that refers to temperature and is called a 

 sigma-t ( c-t ) value. Thus: ^15 = (^15 -1)1000 where Pig is the density 

 of sea water at 15°G (^9°F) referred to pure water at 1;°C (39.2°F) as 

 unity. For example: If sea water has a density at 1^°C of 1.0268, 

 o'ls = 26.8. The actual density of the water may vary from a little 

 less than unity for fresh water at a temperature other than [|.°C to 

 approximately 1.0l|.10 for the heaviest sea water. 



The salinity of sea water, denoted by the symbol °/oo, is defined 

 as the number of grams of salts contained in 1000 grams of sea water. 

 Table I4. gives the salinity corresponding to different values of density 

 at the standard temperature of l5°C. 



