Mass, heat and salt balances in the eastern Barents Sea obtained by inversion of hydrographic section data

Standard hydrological section data, collected in the eastern Barents Sea in September 1997, have been analyzed using a variational data assimilation technique. This method allows us to obtain temperature, salinity and velocity fields that are consistent with observations and dynamically balanced within the framework of a steady-state model describing large-scale nearly geostrophic circulation. Error bars of the optimized fields are computed by explicit inversion of the Hessian matrix. The optimized velocity field is in agreement with independent velocity observations derived from surface drifter trajectories in the southwestern part of the Barents Sea. Optimized fields provide the following estimates of integral characteristics of the circulation in the region: i) the North Cape current transport is 2.12 +/- 0.25 Sv; ii) the Karskie Vorota Strait throughtlow is 0.7 +/- 0.06 Sv; iii) heat flux with Atlantic water is 4.7 +/- 0.16- 10(11) W; iv) salt import from the Atlantic Ocean is 7.41 +/- 0.46.10(3) kg/s. The imbalance of the heat budget in the eastern part of the Barents Sea indicates the presence of statistically insignificant surface heat fluxes which are less than 1 W/m(2).