Transport processes in the Kara Sea

Field data from late summer cruises in 1993-1996 and results from a rotating laboratory model study are used to infer transport routes for contaminants in the Kara Sea on the western Siberian coast. The data show a circulation pattern that differs significantly from published concepts and contains a richer structure. Both the inflowing coastal water from the west and the modified Atlantic Water from the Barents Sea and the Arctic Ocean in the north affect the water properties of the East Novaya Zemlya Trough through mixing, intrusion, and possible transformation during winter convection. Much of the current structure can be explained as a result of topographical steering of the throughflows. Weak summer winds of variable direction affect only the upper layer, whereas persistent strong winds may affect long-term circulation patterns and transports. The main outflow routes are north to the Santa Anna Trough and northeast to the Voronin Trough. The outflowing surface water and ice to the north are expected to join the inflowing Polar Water from the Arctic Ocean that forms the Persey Current into the Barents Sea. Deeper outflows are expected to follow the continental slope to the east in the Arctic Ocean. The laboratory model has been validated to earlier current measurements to the north and south of Novaya Zemlya and shows several of the features observed in the newer field measurements. This suggests that the dynamic similitude and boundary forcing of the model are good. Two notable exceptions are the westward transport of drifting buoys to the north of Novaya Zemlya and the late winter hydrography to the north of the Ob and Yenisey estuaries. Both are probably due to persistent winds. The conclusions from the measured and modeled currents are supported by measurements of Cs-137 in the seawater and sediments.