404 



FISHERY BULLETIN OF THE FISH AND "WILDLIFE SERVICE 



October 1956 +0.35° C. mos.-i June-July 1958 +0.3° C. mos.-' 



November-December 1956 —0.2° C. mos."' November-December 1958 — 0.45° C. mos. ~' 



January-February 1957 -0.5° C. mos.- ^j^^^^ ^^^ ^^ ^ ^^^^^^ ^^ ^^ ^^ ^^ expected 



June 1957 +0.4 C mos. - , , . . . . 



Novembei-December 1957 -0.7° C. mos.-' irom the assumed year-to-year variations in the 



April-May 1958 +0.4° C. mos."' net heat exchange. 



PART III. OCEANOGRAPHIC CLIMATE OF THE HAWAIIAN ISLANDS REGION 



In the first section of this atlas, the distribution 

 of surface variables and their gross seasonal 

 changes in an area bounded by 10° N., 30° N., 

 150° W., and 180°, were described. These con- 

 sisted of surface temperatures, salinities, depths of 

 the mixed layer, and dynamic heights. In the 

 second section, the changes of surface variables 

 were studied in terms of physical processes, such 

 as the net heat exchange across the sea surface and 

 advection. 



In this final section, an attempt wiU be made 

 to use the results of the fu'st two sections to con- 

 struct a climatic model of the Hawaiian region. 

 This, of necessity, will only be a first approxima- 

 tion, since none of the data used here were col- 

 lected for purposes of a climatic study. This first 

 approxmiation, however, may be of use in design- 

 mg experiments to correct and improve the cli- 

 matic model. 



The currents and water masses of the North 

 Pacific were described by Sverdrup et al. (1942, 



ch. XV). They defined the Subarctic Pacific 

 water mass, the Eastern and the Western North 

 Pacific Central water mass, and the Pacific Equa- 

 torial water mass on the basis of temperature- 

 salinity relations below the surface layer. Ap- 

 proxhnately associated with these subsurface water 

 masses one also finds surface water types. These 

 are the Subarctic Pacific Water type, the North 

 Pacific Central Water type, and the North Pacific 

 Equatorial Water type as illustrated in figure 27. 

 On the basis of Schott's (1935) temperature and 

 salinity charts, the Subarctic Pacific type would be 

 cold and have a salinity of 33°/oo or less, the 

 North Pacific Central type would be warm and 

 have 35%o or more, and the North Pacific Equa- 

 torial type would be warm and have about 34%o 

 or less. The chief distinction between water types 

 and masses is that the former are under the direct 

 influence of the physical processes taking place at 

 the sea surface, whereas the latter are not. One 

 would therefore expect relatively large seasonal 



Figure 27. — A schematic chart showing the major North Pacific water types and currents. 



