CIRCULATION NEAR THE WASHINGTON COAST* 



By Clifford A. Barnes and Robert G. Paquette 

 Department of Oceanography 



University of Washington 

 Seattle, Washington, U.S.A. 



Introduction 



The area covered in this paper is a section of the Northeast Pacific 

 Ocean bordering the West Coast of North America between the paral- 

 lels of 44° and 51° North and extending 600 miles seaward (Fig. 1). 

 The coast is mountainous and contributes considerable runoff to the sea 

 from heavy precipitation in winter and the melting of the snow in early 

 summer. Two concentrated sources of fresh water are the Strait of 

 Juan de Fuca and the Columbia River, which drain large inland areas. 

 The Strait differs markedly from the river in that it is the mouth of a 

 large tidal basin and is deeper than 100 fathoms for a considerable dis- 

 tance inshore. As a result of the tidal action, its effluent has been 

 considerably altered by mixing with the cold deeper water. 



The continental shelf, as measured by the 100-fathom contour, ex- 

 tends about 40 miles offshore near the Strait of Juan de Fuca and nar- 

 rows to about 20 miles both northward and southw^ard. Beyond the 

 slope, depths increase gradually to about 2000 fathoms. A number of 

 seamounts rise from this deeper water, but the bathymetry of only a few 

 has been worked out in any detail. 



The climate of the region is predominantly maritime with prevail- 

 ing southwesterly onshore winds accompanied by heavy precipitation 

 from autumn to spring. In summer considerable air flow is from the 

 northwest and north and little precipitation occurs. 



The circulation of the Northeast Pacific is predominantly clock- 

 wise to latitude 40° North, giving way to counterclockwise south of 50° 

 North (Sverdrup, Johnson and Fleming, 1946). The colder water along 

 the northern periphery of the main easterly drift in mid-ocean, the so- 

 called Aleutian or Subarctic Current, splits in all ill-defined zone well 

 seaward from the coast near 45° North, both orientation and position 

 of the zone of divergence varying with the season. The northerly arm, 

 the Alaska Current, recurves through the Gulf of Alaska; and the south- 

 erly arm, the California Current, sets south well offshore at lower lati- 



* Contribution number 194 from the Department of Oceanography of the University of 

 Washington. Technical Report No. 17, University of Washington and Office of Naval Research, 

 Contract N8onr-520/III, Project NR 083-012, and Contract Nonr-477 (01), Project NR 083-072. 



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