TEMPERATURE STRUCTURE IN THE TRANSITION REGION 

 OF THE NORTH PACIFIC 



by 



Margaret K. Robinson and 



University of California 

 Scripps Institution of Oceanography 

 La Jolla, California - 92038 



John Northrop 

 University of California 

 Marine Physical Laboratory 

 San Diego, California - 92152 



INTRODUCTION 



The floating instrument platform, FLIP, was towed by the R.V. HORIZON to 

 39° 30 'N, 148°Wl where she remained on station for 27 days, September 2 to 

 29, 1963. 



This location (Fig l), midway between the Hawaiian Islands, California, 

 and Yakutat, Alaska, in the boundary region between the Subarctic and the 

 Subtropics (Sverdrup, et al . , 1946), was selected by Professor Walter Munk, 

 Scientist-Director of the expedition. His primary purpose was to monitor 

 surface waves in midocean in an attempt to track, from Australia to Alaska, 

 ocean swell generated by storms in the South Pacific. Snodgrass, et al . 

 (1965) have reported the results of this phase of the operation. 



FLIP (Fig 2) is an ideal platform for monitoring the variability of the 

 physical properties of the ocean, including internal and surface waves, 

 (Fisher and Spiess, 1963). Her vertical motion is minimal. Rudnick (1964) 

 has described in detail FLIP'S response to wave motion. He reports behavior 

 in accord with theory; hence, FLIP can be considered to follow the vertical 

 motion of the sea surface very closely at all frequencies well below the 

 resonant frequency (l33 cycles per hour--27-second period) . At higher fre- 

 quencies, the total rms vertical displacement was of the order of 10 cms., 

 even though she encountered storm winds of 20 m/sec and waves of 15 m, under 

 whose battering the R.V.HORIZON rolled 45°. 



The amplitude of the tides at this open ocean location are unknown. 

 Tidal amplitudes in the Hawaiian Islands range between 1.6 to 2.5 feet. It 

 is assumed that the tidal amplitude at FLIP'S location is less than or equal 

 to those in the Hawaiian area . 



The program of oceanographic -observations was planned to take advantage 

 of the fact that FLIP would remain in approximately the same location for 

 almost an entire month. She actually drifted a rhumb line distance of 47 

 nautical miles (87 kms) to the southwest (225°) at an average rate of 1 .7 nm 

 per day, though her true course was erratic and the total scaled track was 

 86 nautical miles (159 kms) . 



405 



