ABSTRACT 



In the area bounded by 10° N., 30° N., 150° W., and 180°, the distribution of surface 

 variables is investigated in terms of associated physical processes. (1) Using all 

 available data, seasonal changes in the distribution of the mixed surface layer, surface 

 temperature, surface salinity, and the dynamic topography are described. (2) With 

 the aid of a simplified heat (salt) budget, the physical processes (net heat exchange 

 across the sea surface, evaporation minus precipitation, advection) and their relation 

 to the distribution of surface variables are analyzed. (3) The results are interpreted 

 in terms of a climatic circulation model in the vicinity of Hawaii. 



The distribution of surface variables reveals three types of climatic boundaries: 

 (1) a depth-of-mixed-layer boundary separating areas in which the time of maximum 

 and minimum depths differs; (2) temperature boundary separating an area where the 

 seasonal range of temperature is relatively constant from one in which it increases 

 northward; (3) salinity boundary separating different types of water. 



Investigation of processes reveals three cold advection periods, June-July, October- 

 November, December-January; the first is dominant in the northwest portion of the 

 area and the second in the southeast portion. In the course of analysis, characteristic 

 advection diagrams, intrinsic temperatures, heat advection charts, and characteristic 

 heating curves are defined. 



In terms of the North Pacific circulation, the salinity boundary is interpreted as 

 separating North Pacific Central water from the transition water of the California 

 Current Extension. The June-July and October-November advection periods reflect 

 dilations and contractions of the North Pacific Central and North Pacific Equatorial 

 circulation systems believed to be associated with the seasonal variation of trade 

 wind intensity. The differing times of maximum and minimum depths of the inixed 

 layer and dominant advection periods reflect the differing climates of the North 

 Pacific Central and North Pacific Equatorial systems. 



