LARGE-SCALE CIRCULATION AND WATER MASS-DISTRIBUTION IN THE ARCTIC-OCEAN FROM MODEL RESULTS AND OBSERVATIONS

We combine results from hydrographic measurements and numerical models to investigate the circulation in the Arctic Ocean. Observations exhi bit a marked difference in the temperature and salinity distribution w est and east of the St. Anna Trough. West of the St. Anna Trough the w arm and saline core of the Fram Strait branch is found close to the sh elf break. East of the St. Anna Trough the highest temperatures and sa linities are found further off shore. A colder, relatively fresh layer of Barents Sea outflow displaces the Fram Strait branch. The numerica l model reproduces these hydrographic structures. It depicts the Baren ts Sea branch as the most important inflow into the Arctic with respec t to heat, fresh water, and volume. The divergence of the heat transpo rt in the Barents Sea is as great as the net heat transport into the A rctic Ocean. A large part of the freshwater input takes place in the a rea of the Barents/Kara Sea. The model transports associated with the Fram Strait branch are smaller because most of the Atlantic water reci rculates in Fram Strait. Bottom topography prays a crucial role for th e model circulation. Our results support previous conceptual models of the Atlantic layer circulation in the Arctic Ocean. The model circula tion is mainly thermohaline driven. Ventilation times for the Eurasian and Canadian Basins below 1-km depth are estimated as 220 and 420 yea rs, respectively.