OCEANOGRAPHIC MEASUREMENTS NEAR 

 THE ARCTIC ICE MARGINS 



by 



Robert G. Paquette 



and 



Robert H. Bourke 



I. INTRODUCTION 



This report describes the results of two cruises in which the meso- 

 scale structure in the water column was measured near the ice margins 

 in the Chukchi and Beaufort Seas. The cruises were part of larger opera- 

 tions directed by the Arctic Submarine Laboratory, Naval Undersea Center, 

 San Diego, and are named MIZPAC 71 and MIZPAC 72. The cruises took 

 place in July and August of 1971 and 1972. The basic measuring tool was 

 the Bissett-Berman salinity-temperature-depth recorder. The data were 

 reduced by tracing the recorder curves with a Calma Digitizer, correct- 

 ing, and computing sound velocity and sigma-t on the Naval Postgradu- 

 ate School IBM 360/67 computer. Computer-generated plots, listings 

 and magnetic tape records were produced. 



The investigation had its origin in reports of severe deterioration of 

 sonar propagation near the ice margins. The effects were presumably 

 due to the existence of complex sound-velocity profiles and rapid changes 

 in propagation conditions with distance. The objectives of the investi- 

 gation were to describe the complex sound-velocity profiles and dis- 

 cover the oceanographic processes which cause and modify them. 



A secondary responsibility was to supply oceanographic data for 

 other programs going on at the same time in the area. 



The two cruises differed somewhat in nature. The first was strongly 

 committed to tending two drifting ice floe stations. This had a strong 

 influence on the area covered and limited the free choice of station posi- 

 tions for the oceanographic purposes. Nevertheless, interesting results 

 were obtained. This cruise also was faced by considerably greater equip- 

 ment problems than was the second. 



The second cruise, although again committed to some other objectives, 

 was able to make a number of closely spaced crossing of the ice margin 

 and also do some exploration in the open water to the south. Equipment 

 problems were few and data was obtained from essentially all of the 114 

 stations occupied. 



