In the first cruise the ice margin was diffuse and generally located 

 in its normal position. In contrast, the ice margin in the second cruise 

 was relatively compact and was much farther to the north. 



In the report which follows, the results of the two cruises are de- 

 scribed separately. The conclusions in the two separate sections are 

 sequential, the second set benefiting from the first set. The overall 

 conclusions from the two sets of data are then given in Section IV. 



II. MIZPAC 71 



A. INTRODUCTION 



In 1971 the research vehicle was the icebreaker USCGS NORTH- 

 WIND, .the time was 30 July to 20 August and the area extended from the 

 northeastern Chukchi Sea to the southwestern Beaufort Sea, as shown in 

 Figure 1. The deepest penetration into the ice was about 30 miles. The 

 icebreaker had other commitments, particularly the shepherding of two 

 drifting ice stations and some search and rescue work. The latter led to 

 the long excursion to the southwest along the coast and resulted in a 

 better understanding of the coastal current than would have resulted had 

 the uninterrupted plan been followed. The manned ice stations required 

 fairly close shepherding by the ice breaker so they could be found and 

 rescued in case of emergency. Also, because the ice stations drifted 

 rapidly into the coastal current and then around Pt. Barrow into the Beau- 

 fort Sea, the area of coverage was shifted eastward from what had been 

 planned . 



On this cruise the rapid changes in water structure near the ice 

 had not been recognized; therefore the closely spaced crossings of the 

 ice margin which were included in the 1972 cruise were not planned 

 specifically. There were opportunities for time series, which were done 

 in 1971 but not in 1972. 



B. TECHNIQUES 



The Bissett-Berman Model 9006 STD was kindly loaned by the 

 U.S. Naval Oceanographic Office. It was termed an "Arctic Model" be- 

 cause the temperature scale extended to -2°C. However, the lower end 

 of the salinity scale extended to only 30o/oo and the instrument would 

 produce neither temperature nor salinity outputs at lower salinities. This 

 left the instrument incapable of sampling the upper 10-15 meters of the 

 water column for roughly 3/4 of the stations. Therefore, the STD was 

 supplemented by a hand-lowered Beckman RS5 conductivity-temperature 

 meter which provided discrete readings. This meter is hereafter called 

 the RS5 . 



