INTRODUCTION 



This study is the third in a series of studies concerned with the analysis 

 of sea-surface temperature observations. The first study dealt with the effect of 

 missing data in long time-series of sea-surface temperature measurements on 

 certain regression and autocorrelation analyses/ The second study examined the 

 use of regression models for time-space interpolation of sea-surface temperature 

 observations . 



This study presents the results of an autocorrelation, regression, and 

 trend analysis of time-series of sea-surface temperature measurements made at 

 six locations representing different oceanographic conditions, and considers the 

 difficulties encountered in applying these techniques to oceanographic data 

 samples.^ An oceanographic interpretation of the statistical results will be pre- 

 sented in a later study. 



Many time-series measurements have been made at various locations. In 

 the eastern Pacific Ocean such measurements have been made by Canadian and 

 American oceanographers at coastal, island, and ship locations for time periods 

 up to 45 years. These data have been the subject of numerous papers including, 

 among others, those of Pickard and McLeod' and Roden."'* This study differs 

 from those cited in that the original daily temperatures are used in the analysis 

 without a preliminary smoothing by monthly averaging. 



The purpose of time-series analysis is to isolate trend, oscillation, and 

 random elements, which are defined as follows. Trend is a gradual increase or 

 decrease in a system over a long period of time; an oscillation is a variation 

 about the trend that occurs with more or less regularity over some time interval; 

 and a random element is an unpredictable variation in the variable. If long-terra 

 trend does not exist, then the primary need is the statistical fitting of some 

 function to time-series to represent the oscillatory element. 



Several sets of daily sea-surface temperatures have been examined, 

 covering two open ocean and four island or coastal locations (fig. 1). To indicate 

 how individual temperature measurements vary throughout the year, 1 year of 

 measurements for each location is presented in figure 2. These years of tempera- 

 tures are taken from records that vary in length from 7 to 40 years. Pertinent 

 information about the stations yielding these records is summarized in table 1. 



The data for station PAPA are being collected by Canadian oceanogra- 

 phers of the Pacific Oceanographic Group, Nanaimo, British Columbia, and are 

 available as a sequence of data reports. Bathythermograph observations are made 

 at 0200 and 1700 GMT. The 0200 GMT data were used for this analysis if the 

 ship were within a 10-minute rectangular area centered at the nominal position. 



KSuperscript numbers denote references in the list at the end of this report. 



