LARGE-SCALE CIRCULATION IN THE BELLINGSHAUSEN AND AMUNDSEN SEAS AS A VARIATIONAL INVERSE OF CLIMATOLOGICAL DATA

Atmospheric and oceanic climatological data art: combined with the Wor ld Ocean Circulation Experiment S4 section hydrology in the framework of a variational data assimilation scheme into a steady state nonlinea r model of the large-scale circulation. The reconstructed fields of de nsity and three-dimensional velocity are dynamically balanced and prov ide qualitative and quantitative estimates of the circulation features of the Amundsen and Bellingshausen seas. Natural assumptions on the s patial structure of the density covariance matrices enable us to obtai n realistic coastal currents near the continental slopes of Antarctica within the framework of model equations. The horizontal circulation p attern reveals along shore westward current with typical velocities of 1 cm s(-1) and cyclonic gyres in the Amundsen and Bellingshausen seas transporting 2 and 0.5 Sv, respectively. The ee eastward branches Of the Antarctic Circumpolar Current are observed in offshore regions. Th eir transports are diagnosed as 19, 12, and 6 Sv. The lower layer is c haracterized by westward countercurrent in the northwestern part of th e basin with the transport of 8 Sv. Average Ekman upwelling rate in th e major part of the basin amounts to 20-25 m yr(-1). Downwelling in th e shelf regions of the Bellingshausen and Amundsen seas is estimated a s 250-350 m yr(-1).