of the stations about the center of NOVEM- 

 BER is sho\v;i in Figure 4. The data is listed 

 !)>• NO DC as Ref. No. 31-833WC and as Table 

 III of this report. 



On the 10-28 February 1067 patrol of the 

 CGC CRESHAM, 18 oceanographic stations 

 were successfully occupied. Seventeen stations 

 had maxinii'm u.seful depths between 1300 and 

 17110 nie ers. The distribution of the stations 

 about the center of NOVEMBER is shown in 

 Figi-rc n. The data is listed by NODC as Ref. 

 No. 31-Fr)2(;H and as Tai)le IV of this report. 



DISCUSSION 



Tully (1955) described the region between 

 10° N and 10 °N in the Pacific Ocean as the 

 "Subtrop'cs." The region is characterized by 

 a heating and cooling cycle which occurs at a 

 high temperature level and the dominant proc- 

 e.ss determining the salinity and temperature 

 s+ructure is evaporation. He stated that there 

 is no permanent ha'ocline in this region ; 

 rather, the salinity of the water is greatest at 

 the surface and decreases to a minimum be- 

 tween 200 and 800 meters depth. Hence, the 

 stability of the density structure is solely de- 

 pendent on the temjierature structure. Also, 

 excess evaporation in this region increases the 

 density of the surface water and promotes a 

 salinity-driven convection which is the domi- 

 nant mixing pi'ocess. 



Ocean Station NOVEMBER (30°00'N, 

 140°00'W) is located in this subtropical re- 

 gion of the North Pacific Ocean and further is 

 located in the eastern gyral in the North Pa- 

 cific which is characterized by a salinity mini- 

 mum at about 500 meters (Sverdrup, et al. 

 1962). This region to the east of the Hawaiian 

 Is'ands between long. 130" and 150 ^W. also 

 encompiisses the boundary between the warm 

 water of the eastern North Pacific and the cold 

 Subarctic water, which flows south along the 

 west coast of America. The bathymetry in the 

 vicinity of NOVEMBER is shown in Figure 6. 

 The U.S. Naval Oceanograi)hic Oflice made 

 prior oceanographic ol)servations in the vicin- 

 ity of NOVEMBER in August 1965 aboard the 

 USNS CHARLES II. DAVIS (T-AGOR 5). 

 A total of 32 stations were occupied including 

 observations of temperature, salinity, nutrients 

 (PO.-P and SiO.-S), currents, biology and 

 continuous records of sea surface temperature. 



bathymetry and incident solar radiation. The 

 data were published as Informal Manuscript 

 No. 66-2, U.S. Naval Oceanographic Office, 

 Washington, D.C. The data collected on the 

 first four Coast Guard Oceanographic patrols 

 were examined to determine the vertical dis- 

 tribution of water mass properties and gross 

 seasonal changes in the water column. Figures 

 7-10 and 11-14, the envelopes of temperature 

 versus depth and salinity versus depth, respec- 

 tively, were constructed to study the vertical 

 structure and its changes between July 1966 

 and February 1967. 



During the heating season between July and 

 October a warm, high salinity water mass was 

 present in the upper 200 meters with a marked 

 seasonal thermocline. Negative gradients of up 

 to 4.0 "C in the first 100 meters were present 

 during the July-August and September-October 

 jxitrols. These large gradients created a very 

 stable density structure. The surface temper- 

 ature reached a maximum of about 22.80°C 

 in September and a minimum of about 18.20°- 

 C in February. The envelopes of salinity versus 

 depth show the presence of a near-surface 

 salinity maximum during the entire period and 

 a'so the increase of the surface salinity from 

 the range of 34.68-34.90%„ in July-August 

 to the range of 35.10-35.28%o in Novem- 

 ber-December. This increase was very likely 

 the cause of convective mixing resulting in the 

 mixed layer which was present in the upper 75 

 meters in November-December. Small insta- 

 bilities were found in this mixed layer which 

 could show the presence of convective mixing. 

 The mixed layer had increased in extent to the 

 100 meter depth in February 1967. The most 

 prominent feature of the salinity distribution 

 was the salinity minimum of 33.95-34.00%o 

 which was found at about 500 meters on all 

 l^atrols except in February when it was located 

 l)etween 200 and 6U0 meters. Below the mini- 

 mum layer the salinity increased uniformly to 

 a value of about 34.55%„ at 1500 meters. 



Figures 15 and 16, the plots of temperature 

 versus time and salinity versus time, respec- 

 tively, at selected levels in the upper 1500 

 meters were constructed to determine the mag- 

 nitude of temporal variations in the water 

 column. It appears that there were large daily 

 fluctuations in the temperature and salinity at 

 the 100 and 200 meter levels. Since spatial 



