0.09 lets.) when a westerly flow shifted south for 

 four hours before suddenly returning to a west- 

 ward direction. Again, interpretation of this 

 change is hampered due to vessel motion and 

 insufficient data. 



The subsurface currents generally coincided 

 with each other in direction and occasionally in 

 speed. However, their relation to the surface cur- 

 rent appears completely independent, with direc- 

 tions often being 180° out of phase (examination 

 of physical data suggests the presence of a strong 

 pycnocline to approximately 10 meters). Station 

 67 is the only exception with rather uniform west- 

 ward flowing currents exhibited during the obser- 

 vation period (fig. 105). Investigation of the pre- 

 dicted tide information further varified the mutual 

 current activity at station 67 in that a slight shift- 

 ing in current direction occurred at all three 

 levels approximately 45 minutes prior to high tide 

 (fig. 110). 



Subsurface currents at all current meter sta- 

 tions were compared with the predicted tide 

 curves (U.S. Dept. of Commerce, 1970) for the 

 Flaxman Island area (70°11'N, 145°50'W) in an 

 attempt to correlate tidal activity with variations 

 in current velocity. Figures 109 to 111 show the 

 tide cycles for the period the current meters were 

 recording. Significant changes in current direc- 

 tion are annotated along the time reference axis of 

 these figures. Current meter stations 23, 67, and 

 69 consistently recorded a change in flow direc- 

 tion approximately one hour before the predicted 

 time of high or low water. There is a slight indica- 

 tion that current direction tends to shift between a 

 NW to NE bearing with the approach of high 

 water, and a S to SE flow with the arrival of low 

 water. Stations 90 and 94 (figs. 107 and 198) 

 exhibited similar dependency to the tide, with 

 exception that shifts in current direction occurred 

 approximately one hour following high or low 

 water. This was probably due to the fact that 

 stations 90 and 94 were 165 miles west of Flax- 

 man Island, while stations 23, 67, and 69 were 

 only 42 miles. The random variation in current 

 speed appears to be independent of tidal activity; 

 however, the weak currents in this area and the 

 errors introduced by vessel motion makes any 

 correlation impossible. 



The limited data from 1971 suggests a two 

 current system with the primary driving forces 

 determining current velocity being a complex re- 

 lation between surface winds and the boundary 

 conditions imposed by continuity. The weak 

 mixed tides (range approximately 15 cm) found in 

 this area appear to have some influence on direc- 

 tion to the subsurface (>10 m) currents. 



CONCLUSION 



1. Dynamic equilibrium is poorly developed 

 or absent in the surface waters of the western 

 Beaufort Sea. Wide variations in temperature and 

 salinity reflect the lack of steady-state conditions. 



2. The water masses in the upper 200 meters 

 of the western Beaufort Sea during the summer 

 are affected by seasonal heating, wind mixing, 

 icemelt, and continental runoff; however their 

 relative importance in the area is still somewhat 

 unclear. 



3. Limited data suggests a two current system 

 on the continental shelf with the primary driving 

 forces determining current velocity being a com- 

 plex relation between surface winds and the 

 boundary conditions imposed by continuity. The 

 weak mixed tides (range ~ 15 m) found in the 

 area appear to have some influence on direction of 

 the subsurface (> 10 m) currents. 



4. The general concentration of nutrients in 

 the surface waters are very low with large spatial 

 variations occurring because of icemelt, river 

 runoff and advection. At the shallow pycnocline a 

 nutrient minimum was found and is probably due 

 to phytoplankton activity. 



5. The distribution of dissolved oxygen as a 

 function of depth, season, and nutrient concen- 

 tration indicates that the high dissolved oxygen 

 saturation values at the pycnocline during 

 WEBSEC-71 may result from in situ 

 photosynthetic production of oxygen rather than 

 just atmospheric exchange. To test this 

 hypothesis, a method similar to Codispoti and 

 Richards (1971) was attempted. Initial nutrient 

 (phosphate and nitrate) and oxygen concentra- 

 tions were assumed using values from the deep 

 shelf with saturation near 100% (table 4). Final 



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