INTRODUCTION 
The summaries of sea water temperatures and densities presented in 
this publication are based on observations made at locations along the 
Pacific coast of North and South America and Pacific Ocean islands through 
the year 1969, 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 (formerly Coast and Geodetic 
Survey), often with the cooperation of other organizations. The data for 
six places on the California coast, namely La Jolla, Balboa, Port Hueneme, 
Pacific Grove, Southeast Farallon Island and Blunts Reef Lightship were 
Supplied by the Scripps Institution of Oceanography. The data for places 
in Chile were supplied by the Departamento de Navegacion e Hidrografia, 
Republica de Chile. Other observations in Latin America were obtained 
through cooperation with the Inter American Geodetic Survey. Data for the 
Philippine Islands were supplied by the Bureau of Coast and Geodetic Survey 
of the Republic of the Philippines. For places in other countries the 
National Ocean Survey (formerly Coast and Geodetic Survey) derived the data 
from observations made by organizations in the particular country. 
Table 1 presents monthly means and annual means and extremes of the 
surface water temperatures and densities for each year of observation after 
1964, Earlier observations are combined in five-year groups. For each 
station at which the series of observations covered two or more years, the 
following monthly values are presented: 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 observations had 
been available for all months in which the maximum or minimum normally occurs. 
If observations are not available for any month 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 thermometer 
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 2, 
The density of any substance is defined as the mass. per unit volume. 
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 some standard temperature in order that they may 
be comparable. In this publication the observed densities have been reduced 
to a standard temperature of 15 C (59 F). The density of pure water at a 
temperature of 15 C is taken as 0.9991. The density values obtained by 
using a hydrometer were reduced to the standard temperature by using the 
tables given in C&GS Special Publication No. 298. 
Densities in Table 1 are expressed in terms of the Greek letter eG 
with a subscript that refers to temperature and is called a sigma-t (¢ 
value. Thus: 9¢,, = ( @,-1) 1000 where A, is the density of sea water at 
15°C (59°F) referred to pure water at 4°C (39.2°F) as unity. For example: 
If sea water has a density at 15°C of 1.0268, o«,, = 26.8. The actual 
density of the water may vary from a'little less than unity for fresh water 
at a temperature other than 4°C to approximately 1.0410 for the heaviest 
sea water, O° 
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 3 
gives the salinity corresponding to different values of density at the 
standard temperature of 15°c. 
