Investigation of the Weddell Sea Coastal Current 

 February- March 1970 



Gary L. Hufford ' 

 James M. Seabrooke ^ 



INTRODUCTION 



The Coastal Current in the Weddell Sea has 

 been hypothesized as a major component in the 

 formation of Antarctic Bottom Water (Sea- 

 brooke, Hufford, and Elder, 1971), but only a 

 few observations have been made in it. This 

 current has been found to exist from the sur- 

 face to the bottom in the eastern Weddell Sea 

 exhibiting uniformity in current direction 

 (southei'ly) (Gordon, 1970). Sverdrup, et al. 

 (1942), suggested that the westward flow of 

 the Coastal Current east of the Weddell Sea is 

 due to an extensive clockwise gyre which oc- 

 curs in the Southern Ocean. 



DATA ACQUISITION 



From February 14 to March 21, 1970, an 

 oceanographic investigation (32 stations) of 

 the eastern Weddell Sea Coastal Current by the 

 Coast Guard Oceanographic Unit was con- 

 ducted aboard the icebreaker USCGC GLA- 

 CIER (WAGB-4) as part of the International 

 Weddell Sea Oceanographic Expedition (fig. 1). 

 Hydrographic data were obtained using Nansen 

 bottles with reversing thermometers, current 

 meters, and a continuous salinity-temperature- 

 depth recording system (STD) with a Niskin 

 multisampler attached. Sampling was con- 

 ducted to as close to the sea floor as possible. 

 The resulting water samples were analyzed 

 manually at sea for dissolved oxygen, inorganic 

 phosphate, ni4;rate, nitrite, and silicate using 

 the techniques described in the manual of 

 Strickland and Parsons (1965). Salinity was 



1. U.S. Coast Guard Oceanoeraphic Unit. WashinKton. D.C. 20390. 



2. U.S. Coast Guard Oceanographic Unit. Present Address: U.S. 

 Coast Guard Training Center, Governors Island, New York, N.Y. 

 10004. 



determined using an inductive salinometer. The 

 conductivity values obtained were converted to 

 salinity by use of the International Oceano- 

 graphic Tables published jointly by UNESCO 

 and the National Institute of Oceanography of 

 Great Britain (1966). A summary of data col- 

 lected at each station is given in Table 1. 



Direct measurements of currents from the 

 surface to the bottom were made at Halley Bay 

 (fig. 1). The ship was anchored to the fast ice 

 and continuous measurements were taken for 

 two days. The current data are being processed 

 by the University of Bergen, Norway, and the 

 results will not be reported here. 



Eight oceanographic stations of opportunity 

 were occupied in the Bransfield Strait region 

 during 6-29 January 1970 to determine if any 

 flow of Antarctic Bottom Water from the 

 Weddell Sea occurred there as suggested by 

 Hollister and Elder (1969). The data indicated 

 water with Antarctic Bottom Water character- 

 istics (-.4 °C, 34.66 %o) was not present. 



WATER MASS DISTRIBUTION 



Analysis of the temperature-salinity rela- 

 tions of the data obtained during IWSOE-70, 

 revealed three water masses present in the 

 Coastal Current: Antarctic Surface Water, 

 Warm Deep Water, and a Bottom Water 

 (fig. 2). The properties of these three water 

 masses (Table 2) closely resemble those ob- 

 served previously by Hufford and Seabrooke 

 (1970). 



Above the eastern continental shelf of the 

 Weddell Sea, the water column is occupied 

 by one water mass, Antarctic Surface Water 

 (T = — 0.8 to — 1.9°C, S = 33.50 to 34.50o/oo) 

 (fig. 2). This water mass shows an increase in 



