Four years of temperature, salinity, and velocity data enable a direct computation of volume transport and a temporal description of water properties exchanged through the Bering Strait. The mean volume transport over the 4‐year period (September 1990 through September 1994) is 0.83 Sv northward with a weekly standard deviation of 0.66 Sv. The maximum error in this mean estimate is 30%. Interannual variability in transport is typically 0.1 Sv but can, at times, reach nearly 50% of the mean. The transport of 1.14 Sv during the first 9 months of 1994 is the largest in the last 50 years. The rate of winter salinity increase is very similar from year to year, suggesting regional average ice formation of about 5 cm d−1. The amplitude of the annual salinity cycle is about 2 psu, with salinity reaching a maximum in early April. There can be large interannual variations in the salinity (about 1), particularly in winter. Background autumn salinities average 32.0 in the eastern and 32.6 in the western channel.

Abstract. We describe circulation and mixing in the Siberian Coastal Current (SCC) using fall shipboard measurements collected between 1992 and 1995 in the western Chukchi Sea. The SCC, forced by winds, Siberian river outflows, and ice melt, flows eastward from the East Siberian Sea. It is bounded offshore by a broad (---60 km) front separating cold, dilute Siberian Coastal Water from warmer, saltier Bering Sea Water. The alongshore flow is incoherent, because the current contains energetic eddies and squirts probably generated by frontal (baroclinic) instabilities. These enhance horizontal mixing and weaken the cross-shore density gradient along the SCC path. Eventually, the SCC converges with the northward flow from Bering Strait, whereupon it deflects offshore and mixes with that inflow. Deflection occurs where the alongshore pressure gradient The foregoing description implies that the SCC is largely driven by the positive buoyancy influx provided by river discharge. However, winds also play an important role on these 29,697

[1] The summer circulations and hydrographic fields of the Kara Sea are reconstructed for mean, positive and negative Arctic Oscillation regimes employing a variational data assimilation technique which provides the best fit of reconstructed fields to climatological data and satisfies dynamical and kinematic constraints of a quasi-stationary primitive equation ocean circulation model. The reconstructed circulations agree well with the measurements and are characterized by inflow of 0.63, 0.8, 0.51 Sv through Kara Gate and 1.18, 1.1, 1.12 Sv between Novaya Zemlya and Franz Josef Land, for mean climatologic conditions, positive and negative AO indexes, respectively. The major regions of water outflow for these regimes are the St. Anna Trough (1.17, 1.21, 1.34 Sv) and Vilkitsky/Shokalsky Straits (0.52, 0.7, 0.51 Sv). The optimized velocity pattern for the mean climatological summer reveals a strong anticyclonic circulation in the central part of the Kara Sea (Region of Fresh Water Inflow, ROFI zone) and is confirmed by ADCP surveys and laboratory modeling. This circulation is well pronounced for both high and low AO phases, but in the positive AO phase it is shifted approximately 200 km west relatively to its climatological center. During the negative AO phase the ROFI locaion is close to its climatological position. The results of the variational data assimilation approach were compared with the simulated data from the Hamburg Shelf Ocean Model (HAMSOM) and Naval Postgraduate School 18 km resolution (NPS-18) model to validate these models.

[1] We compare daily data from the National Center for Atmospheric Research and National Centers for Environmental Prediction ''Reanalysis 1'' project with observational data obtained from the North Pole drifting stations in order to validate the atmospheric forcing data used in coupled ice-ocean models. This analysis is conducted to assess the role of errors associated with model forcing before performing model verifications against observed ocean variables. Our analysis shows an excellent agreement between observed and reanalysis sea level pressures and a relatively good correlation between observed and reanalysis surface winds. The observed temperature is in good agreement with reanalysis data only in winter. Specific air humidity and cloudiness are not reproduced well by reanalysis and are not recommended for model forcing. An example sensitivity study demonstrates that the equilibrium ice thickness obtained using NP forcing is two times thicker than using reanalysis forcing.

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