Bottom Photography 



A Thorndike X1959) type bottom contact 

 camera system was used for bottom photo- 

 graphs. The camera system was set up to take 

 a photograph when the camera lens was three 

 feet above the bottom and at a sixty-degree 

 angle from the vertical. The ship's photogra- 

 pher developed the film, the compass-oriented 

 photographs revealed many benthic organisms 

 as well as current ripple marks. 



Results of Preliminary Analysis 



Due to the limited number of oceanographic 

 stations (27) only one vertical section was se- 

 lected for analysis (figure 2-7). 



Analysis of the data using preformed nutri- 

 ents (figures 5-6) as well as temperature and 

 salinity (figures 2-3) indicate that three water 

 masses were present in the southeast Weddell 

 Sea (table 2). These were the water mass 

 found on the continental shelf; a warm intru- 

 sion which was found from about 400 meters 

 to 1600 meters depth off the shelf ; and the bot- 

 tom water mass which may or may not be Ant- 

 arctic Bottom Water. 



The temperature and salinity distribution of 

 the shelf water and warm deep water showed 

 that the bottom water present could not be 

 produced by mixing of these two masses (fi- 

 gure 2-3). Deacon (1937) postulated that the 

 formation of Antarctic Bottom Water takes 



place only in the southwestern Weddell Sea. 

 Elder and Seabrooke (in press) found forma- 

 tion of Antarctic Bottom Water in the south- 

 western Weddell Sea, (west of 40° longitude) 

 during IWSOE '68 by mixing of dense shelf 

 water with warm deep water. Data from 

 IWSOE '69 indicates that Antarctic Bottom Wa- 

 ter formation does not take place in the south- 

 eastern Weddell Sea (east of 40° longitude) in 

 the summer. 



A question arises as to where the bottom 

 water comes from in the cross section for 

 IWSOE '69. Bottom photographs obtained 

 from the USNS Eltanin and IWSOE '68 (Hol- 

 lister and Elder, 1969) indicate a westerly flow- 

 ing bottom current which follows the bathyme- 

 tric contours in the southern Weddell Sea. 

 Only a few photographs were obtained during 

 IWSOE '69, but they also suggest a westerly 

 flowing bottom current. Therefore, the bottom 

 water present in the southeast Weddell Sea in 

 1969 may be part of the westerly flowing Ant- 

 arctic coastal current which is evident only in 

 the Weddell Sea area, where an extensive cy- 

 clonic motion occurs to the south of the Cir- 

 cumpolar current (Sverdrup, Johnson and 

 Fleming, 1942). Further investigation is being 

 conducted to determine the origin of the bot- 

 tom water found in the southwestern Weddell 

 Sea. Data collected during IWSOE '70 will 

 hopefully add light to the problem. 



