Thereafter, a standard procedure was adopted for all stations. When the ship 

 had stopped, a bathythermograph was first lowered to the bottom. The slide thus 

 obtained was placed with its grid in a photographic enlarger and projected to show 

 the thermal structure. From this trace, the depths of water sampling were selected. They 

 usually included at least the surface, a depth just above the thermocline, one below the 

 thermocline, and one near the bottom. The number of samples taken depended upon 

 the complexity of the thermal structure and the depth to the bottom, but usually ranged 

 from five to seven. 



Nansen bottles without attached thermometers were placed appropriately on 

 the line to take water samples at the selected depths. A record of the temperature was 

 obtained from the bathythermograph secured to the end of the same line. The complete 

 operation took about 15 minutes and was repeated about every two hours if the ship 

 remained at the same location. 



A single 180-foot-maximum-depth (Bristol 20120) bathythermograph was used 

 for 554 lowerings and a 450-foot instrument was used for 27 lowerings in the area of 

 the southeastern Bering Sea. Additional observations (such as plankton-net hauls, 

 bottom samples, surface-current and bottom-current measurements) were made at 

 selected stations and have been reported separately. 114 



Salinity analyses and preliminary analysis of bathythermograms were performed 

 aboard ship for several reasons. They made it possible to evaluate and modify the 

 over-all program in the field, to determine and obtain the most pertinent information 

 in the time available, to determine the proper operation of gear, and to avoid accumula- 

 tion of water samples. 



The BT slides were placed in a grid, adjusted for preliminary temperature 

 corrections, and projected and traced on mimeographed grid prints which had been 

 prepared in advance. The water samples were titrated on shipboard and the salinity 

 calculated to an accuracy of ±0.05 °/oo- The salinity was then plotted on the grid 

 with the temperature trace. Density values (o>) were calculated by means of a nomogram 

 and also plotted on the grid. From these vertical traces preliminary geographic sections 

 of temperature, salinity, and density were prepared. This procedure of shipboard 

 preliminary processing proved to be highly satisfactory. 



Detailed processing and analysis were carried out ashore. The serial data are 

 tabulated and horizontal and vertical sections of temperature, salinity, and density 

 distributions are given in volume 2 of this report. 



geography 



The eastern Bering and Chukchi Seas lie on the broad continental shelf of Alaska. 

 The continental shelf is remarkably flat, varies in depth primarily between 20 and 30 

 fathoms, and has a mud and sand bottom shoaling gradually and regularly toward 

 the coastline. Detailed descriptions of the topography and sediments of the region are 

 given in the first report of this series 1 and a report of the NEREUS cruise in 1947. 13 



The shallow coastal seawater system is bounded on the southwest and south by 

 the deep Bering Sea and the Aleutian Islands, on the east by the coast of Alaska, on 

 the west by Siberia, and on the north by the Arctic Ocean. The system is divided into 

 two distinct regions by the Bering Strait which separates the Bering Sea from the Chukchi 

 Sea. Oceanic water is supplied to the southern part of the system by the flow northward 

 through the eastern Aleutian Islands and perhaps also by a weak northeastward flow 



14 Navy Electronics Laboratory, Report 148 Oceanogrophic Cruise to the Bering and Chukchi 

 Seas, Summer 1949; Interim Summary Report 19 October 1949 (CONFIDENTIAL). 



