II. OCEANOGRAPHY 

 by Ko Newsom, L, Francavillese, and J. Tierney 



A. Water Types of the Ross Sea 



During DEEP FREEZE 62, the majority of the oceanographic work was accom- 

 plished in the Ross Sea. For the purposes of this report, the Ross Sea is defined 

 as that portion of the great southern ocean that is set off between Cape Adare on 

 the northwest and Cape Colbeck on the southeast, with an additional assignment 

 of most of the oceanic area northward to about 70° South Latitude. Data were 

 collected during January and February; therefore, this discussion deals only with 

 the summer period. 



In general, there are three identifiable water types in the Ross Sea: (1) Upper 

 Water, (2) Circumpolar Water, (3) Shelf Water. 



(1) Upper Water is practically homogeneous in winter. During the summer, the 

 temperature of the upper 100 to 200 meters is raised by the increased solar radiation, 

 and the salinity is reduced by the associated input of melt water. This warmer, 

 less-saline layer is termed Antarctic Surface Water by Deacon. The deeper portion 

 of the Upper Water is not similarly affected, and it more or less maintains winter 

 conditions all year around; hence, its designation Winter Water by Mosby. Upper 

 Water is a consistent feature of the water column seaward of the continental slope 

 and is present over the continental shelf in the southeastern Ross Sea (Figs. 3 and 

 4). 



The term Antarctic Surface Water is extended to include the warmer, less- 

 saline layer that develops at the surface in areas where Winter Water is not found. 



(2) Circumpolar Water is a continuation southward of Antarctic Deep Water; it 

 has a core of maximum salinity slightly greater than 34.70%o.at about 2000 meters 

 below the surface and a temperature minimum warmer than + 0.50°C. This deep 

 layer rises near the Antarctic continent where it becomes known as Circumpolar 

 Water, but it still retains the basic characteristics of Deep Water. At Station B-13 

 (Fig. 3) just off the edge of the continental shelf, the core of the Circumpolar 

 Water lies ot about 500 meters depth. A portion of this water mass moves up the 

 continental slope and extends as a wide tongue-like wedge, becoming locally mod- 

 ified as it penetrates into the Ross Sea . It Is altered from above by mixing with 

 Antarctic Surface Water and, to a lesser extent, from below by the cold, saline 

 Shelf Water over which it moves (Figs. 3 through 5). In the southeast sector of the 

 Ross Sea, the Intrusive Circumpolar mass is modified most by contact and mixing with 

 Winter Water. The core of this mass, i .e . the zone of maximum temperature and 

 minimum oxygen, can be traced by oxygen minima to within about 50 meters of 

 the surface at Station B-02 in the western Ross Sea (Fig. 5). Additional data are 



