study period. In particular, a 

 knowledge of the movement of the 

 thermal fronts over the period of 

 the SLAR surveys is essential 

 when the images are compared to 

 the surface data. The length of 

 each hydrographic phase was 

 limited to no more than 6 days 

 due to the short endurance of the 

 survey vessel. 



Phase one consisted of 50 CTD 

 (conductivity, temperature, and 

 depth) stations and 70 XBT sta- 

 tions. This phase consisted of six 

 hydrographic lines, four oriented 

 north-south and two east-west, 

 and one XBT line, a diagonal. 

 The CTD station spacing along 

 the hydrographic lines was 18 km 

 (10 nm), with an XBT cast taken 

 half way between the CTD 

 stations. The station spacing 

 along the XBT line was 9 km 

 (5 nm). 



The CTD casts were taken to 

 about 1 000 m or to within 50 m of 

 the bottom at stations shallower 

 than 1000 m. To verify CTD 

 results, deep quality control 

 samples were taken at most 

 stations using a Nansen bottle 

 with reversing thermometers. 

 XBT stations were made with T-4 

 XBT's, which provide a tempera- 

 ture profile to 450 m. 



High winds and seas further 

 constricted the time available for 

 sampling during phase two. 

 BITTERSWEET was unable to 

 complete the oFiginally-planned 45 

 station star pattern, and com- 



pleted 38 CTD stations and 48 

 XBT deployments. As in phase 

 one, CTD station spacing was 18 

 km (10 nm) and XBT casts were 

 conducted about halfway between 

 the CTD stations. 



This research cmise marked the 

 first operational use of Ice Patrol's 

 f^obile Oceanography Laboratory 

 (MOL). BITTERSWEET is a buoy 

 tender with no special equipment 

 for oceanographic sampling, thus 

 all sampling and analysis equip- 

 ment had to be brought aboard for 

 the cruise and removed after its 

 completion. 



The MOL consists of a 4.2 X 2.4 X 

 2.4 m (14 X 8 X 8 ft) steel shipping 

 container, which was attached to 

 brackets welded to BITTER- 

 SWEET's buoy deck. The interior 

 of the MOL is fitted with desks and 

 equipment racks containing the 

 computers that retrieve and store 

 data from the CTD and XBT 

 systems, as well as a global 

 positioning system (GPS) receiver. 



An electrically-powered, portable 

 oceanographic winch with about 

 2000 m of 1/4" (0.6 cm) armored 

 hydrographic cable was chained to 

 the buoy deck. The final compo- 

 nent of the sampling system was a 

 portable hydrographic platform 

 with a hydraulically operated A- 

 frame, which was placed in the 

 buoy port. All of this equipment 

 can be installed in one day and 

 removed in about four hours. 



Drifting Buoys 



The drifts of satellite-tracked 

 buoys were used to determine the 

 current speed and direction in the 

 study area. The buoys were 3 

 meter long spars with a 2 X 10 

 meter window-shade drogue 

 attached at the end of a 50 meter 

 tether. The accuracy of the 

 position data is about 350 m. The 

 buoys were fitted with temperature 

 sensors (accuracy ~1°C) 

 mounted approximately 1 m below 

 the buoy's waterline. Each buoy 

 received about 8 fixes per day. 



Eight drift tracks are used for this 

 study. Of these, two are from 

 operational buoys deployed in the 

 Labrador Current well north of the 

 study area by Ice Patrol's recon- 

 naissance aircraft (HC-1 30). They 

 moved southward along the 

 eastern edge of the Grand Banks 

 (Murphy and Thayer, 1987) and 

 passed through the study area 

 shortly before BITTERSWEET 

 arrived on scene. The remaining 

 drift tracks are from buoys de- 

 ployed from BITTERSWEET, most 

 of which were recovered after the 

 experiment concluded. 



SLAR Surveys 



Four SLAR surveys, on 2, 6, 14 

 and 20 May, mapped the features 

 in the study area. On two dates 

 (15, 18 May) portions of the study 

 area were mapped during routine 

 iceberg patrols. The Ice Patrol 

 SLAR is an X-band (3 cm wave- 

 length), real-aperture radar that 

 produces a continuous 9" (23 cm) 

 analog image on film. When the 



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