SURFACE WATER TEMPERATURES 

 PACIFIC COAST 



Thxs puDiication supersedes mimeographed pamphlet TW-2, "Water 

 Temperatures, Coast and Geodetic Survey Tide Stations, Pacific 

 Coast", issued in April 1941. Eight new stations have been added; 

 five along the California coast, two m the Aleutian Islands and 

 one at Midway in the Hawaiian group. The temperature data con- 

 tained in this publication are based on observations through 1944. 



The publication is divided into two parts. Part I consists 

 of stations where three or more years of continuous observations 

 are available. For these stations a table of expectancy range has 

 been computed. This table follows the table of means and extremes 

 for the station and shows the percentage of times in which indi- 

 vidual temperature readings agree with the average monthly means 

 within the limits indicated. The average percentages given m the 

 right-hand column of this table are the means of the corresponding 

 12 monthly values. Part II consists of stations where less than 

 three years of continuous observations are available, together with 

 results for five stations furnished by the Scrlpps Institution. 



The temperature observations usually consist of single read- 

 ings each day made by the tide observer at the time of securing 

 the tide record. The tide observer is not required to visit the 

 station at any specified hour, nor at the same hour each day, 

 neither is he required to visit it on Sundays and holidays . How- 

 ever, the visits are usually made during daylight hours, and it 

 may be assumed that in the course of a year the distribution of 

 the observations is fairly uniform over all phases of the tide. 



The water samples are drawn with a bucket from near the sur- 

 face and may be regarded as giving the temperature of the first 

 foot of water. The readings are made in the bucket immediately 

 after the sample has been drawn and before it has had time to be- 

 come affected appreciably by the temperature of the surrounding 

 air. At some stations recording thermometers are being installed. 

 These, of course, give a continuous record. The bulb of the re- 

 cording thermometer is set a foot or two below the lowest tide. 



In the table of means and extremes for each station, the value 

 for any month of a given year represents the average or mean value 

 of the observed readings for that month. In the three columns at 

 the extreme right of the table are given, respectively, the mean 

 temperature for the given year, and the maximum and minimum tem- 

 peratures observed during the year. In the three bottom lines of 

 the table are given, respectively, the means for the different 

 months and the extreme values for each month from the whole series 

 of observations. • The monthly means may be taken as applying to the 

 middle of the month, and the mean values at other times of the 

 month may be determined by interpolation. 



