Figure B-4. The location of the 

 hydrographic survey conducted by 

 International Ice Patrol from the 

 USCGC HORNBEAM, 1-11 July 1984 



period Of 6 -10 July (188-192) 

 (when the buoy followed the 

 geostrophic flow), the 

 thermocline depth was about 

 20m for the area through which 

 the buoy drifted. For this period, 

 the drogue was below the middle 

 of the thermocline. 



East of 46O30'W, the observed 

 geostrophic current field became 

 less distinct. By the time TOD 

 #2633 crossed 460W on 20 July 

 (202) , the hydrographic data was 

 10 days old. The observed 

 currents east of 46° W were weak. 

 The current field of that particular 

 area has a high degree of 

 variability (Soule, 1964; Scobie 

 and Schultz, 1976). Forthe 

 period of 24 July - 1 August (206- 

 214), TOD #2633 more closely 

 followed the wind current (Figure 

 B-7). The thermocline depth 



57W 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39W 

 -■ '—r-l 1 1 1 h-i— I 1 1 1 1 1 1 1 1 1 



40N 



H 1 1 1 ( 1 1- 



< 1 1 1 1 1 1- 



52N 

 ■51 

 •-50 



49 



48 

 •47 



46 

 + 45 



44 



43 

 ■ ■42 



41 



57W 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39W 



40N 



varied between 35m and 40m, 

 indicating the drogue was above 

 the middle of the thermocline, 

 and thus, in the surface mixed 

 layer. To illustrate this effect, the 

 buoy motion is compared with a 

 calculated wind driven current 

 based on McNally (1981). He 



used 1 .5% of the wind speed 

 directed 30° to the right of 

 downwind. Measured winds from 

 HORNBEAM were used to 

 calculate the wind driven current 

 when available. Otherwise, 

 FNOC winds were used. 



Figure B-5. Hydrographic cast stations taken from USCGC Hornbeam 1-11July1984 



61 



