Its area is about 883,000 km and its volume 98,000 km. Over 80% of the area and 77% of the volume constitutes a shelf zone with depths less than 200 m. The mean depth is 111 m and the maximum 620 m (located in the northern section at about 80 N and 71 E). The seafloor is chiefly a series of platforms or broad terraces stepping downward from the southeast to the north and west. The most prominent features are the St. Anna (up to 610 m deep) and Voronin (up to 450 m deep) troughs. Between these is the Central Kara plain with depths less than 50 m. Along the Novaya Zemlya coast is the Novozemel'sky depression reaching depths greater than 400 m.
Zenkevitch (1963) gives the history of the exploration of the Kara Sea to 1955:
The first data on the Kara Sea were collected by the Swedish expeditions of O. Nordenskjöld in 1975 (in the Pröven), in 1876 (in the Imer) and in 1878 (in the Vega). In 1882 and 1883 biological work was carried out there by a Dutch expedition in the Varna and by a Danish one in the Dymphna. In 1893 the Kara Sea was surveyed by Nansen's famous Fram, in 1900 by Toll's Russian expedition in the Zarya, in 1907 by the expedition of the Duke of Orleans in the Belgica and in 1918 by R. Amundsen in the Mod. All these expeditions have contributed to the study of the Kara Sea fauna.
A comprehensive study of the Kara Sea and its fauna was begun as recently as 1921 by the expedition of the Oceanographic Institute in the Malygin and by that of the Hydrographic Directorate in the Taimyr. In subsequent years a number of Soviet expeditions of the Arctic Institute and the Committee of the Northern Sea Route cruised in the Kara Sea. Among them the voyages of the Sedov (1929, 1930 and 194), Lomonosov (1931), Rusanov (1931 and 1932) and others, and particularly the expeditions of the Sadko (1936, 1936 and 1937) which sailed to the north of the Kara Sea far into the Arctic basin and which was the first to haul bottom fauna from depths of almost 4,000 m, are of especial interest. The results of the expedition of the trawler Maxim Gorky in 1945 were of importance. During the Soviet period the number of expeditions working in the Kara Sea has been more than doubled in comparison with those of all previous years.
A significant feature of the Kara Sea is the large input of freshwater from rivers. The total volume is about 1525 km yr and is chiefly from the Ob (400 km yr), the Pur (30 km yr), the Taz (34 km yr), the Yenisey (630 km yr) and the Pyasina (50 km yr). The water masses are controlled by this contintal runoff as well as by water inflows from the Arctic Basin and Barents Sea. In the southwest, bottom water forms from winter cooling and increased salinity from ice growth. Above this are saline Barents Sea water (-1.90-6.00 C, 35.30-35.60) and Arctic surface water (-1.80 C, 32.00). In the north deep Atlantic water penetrates into the Kara Sea from the Arctic Basin via the St. Anna and Voronin troughs. On top of this are the Arctic surface water and, below that, the winter Kara Sea surface water (-1.40 C, 22.00-25.00).
The general circulation is influenced by the relative strengths of the Arctic High and Icelandic Low. When the former prevails, water masses are transported from south to north, river outflow increases, the inflow of Barents Sea water decreases. These combine to reduce surface water salinity, increase sea level, thicken the surface layer, and position the Atlantic water nearer to the surface layer. When the Icelandic Low is prevalent, water masses are transported from west to east, Barents Sea inflows increase, Kara Sea outflows to the Arctic surface water increase, the sea level and and the surface water layer both decrease, and the depth of the Atlantic water increases. See Zenkevitch (1963), Fairbridge (1966), Pavlov and Pfirman (1995), Pfirman et al. (1995) and Johnson et al. (2000).
The circulation consists of two northwestward flowing surface currents originating from the two passages providing connections to the Baltic, one on either side of the basin, and a southeastward flowing countercurrent to the west of the eastern current that flows along the Swedish coast. The flow from the two northwestward currents, jointly called the Baltic Current, eventually combines and joins the North Jutland Current (NJC) as it turns around and becomes the Norwegian Coastal Current. The countercurrent originates as part of the NJC turning and flowing southeast. See Svansson (1975) and Danielssen et al. (1997).
KESS will deploy eight reciprocal tomography moorings in the Kuroshio Extension (centered on 35N, 150W) for four years to study the climatological relevance of the Kuroshio Extension/mode water variability.
It was at this point that Kircher launched into the realms of sheer speculation. The broad north Atlantic flow into the northern regions was supposed to be drawn into the earth's interior at the north pole and released at the south pole, with the process occurring rhythmically to additionally offer an explanation for the periodicity of the tides. He also included small spotlike features on the map that were supposed to be locations of whirlpools and entrances to a vast system of subterranean channels, one example being an entrance/exit pair on either side of Panama to facilitate the postulated broad western flow pattern. See Peterson et al. (1996).