SEAWATER OBSERVATIONS ON THE PACIFIC COAST OF CANADA 707 



factors creating this summer freshet, such as solar insolation, previous 

 winter snowfall, and wind, is easily monitored by the simple observation 

 of the changes in seawater salinity. 



The third type of marine climatic region is that where the annual 

 salinity variation is very slight. On the Canadian Pacific Coast, this 

 can be further divided into two sub-classes, one where the station is 

 exposed to the deep open ocean (Langara) and the other where the 

 station is located in a turbulent water-way (Race Rocks). There is very 

 little annual salinity variation at Langara, but the records will demon- 

 strate the year to year changes caused by major alterations in the system 

 of offshore circulation (Figs. 6 and 7). To measure these large scale 

 circulation patterns is a major oceanographic undertaking, and is some- 

 times not possible owing to lack of facilities. But an idea of the extent 

 of the change in unsurveyed periods can be estimated from surface sea- 

 water observations made at the exposed ocean stations. 



The annual salinity changes observed in turbulent sea-ways serve 

 to measure the extent of mixing of the more saline deep waters with 

 the less saline surface waters. The Fraser River flows into Georgia 

 Strait and is eventually discharged to the ocean past Race Rocks in the 

 Juan de Fuca Strait. It may be noted that there is a slight drop in sa- 

 linity at Race Rocks during the month of August, following a large 

 decrease in salinity during June and July at Entrance Island, further 

 north in the Strait of Georgia. Comparison of the records in these two 

 stations which are subject to the influence of the one major river, shows 

 the difference of the degree of this influence in adjacent and connecting 

 regions. 



Combining both water temperatures and salinity records, it is pos- 

 sible to measure the annual seasonal fluctuations in the oceanic climate. 

 This is a simpler method than trying to evaluate the more variable at- 

 mospheric phenomena from meteorological records and applying their 

 effects on the oceanic state. 



Monitoring Oceanographic Conditions 

 The oceanographer determines the changes that occur in the sea 

 from year to year and from season to season by conducting detailed 

 examinations of the various properties of sea water, chiefly the tempera- 

 ture and salinity. On the Pacific Coast of Canada there are several 

 general types of oceanic regions, each demonstrating a typical pattern 

 of seasonal variation in the properties of temperature and salinity. This 

 pattern is similar from year to year, but the extent and duration of the 

 change from one season to another varies. The seawater sampling sta- 

 tions have been located in such a way that they sample the ocean waters 



