Satellite altimetry observations of the Black Sea level

The paper is devoted to the application of satellite altimetry from the TOP EX/ Poseidon and ERS-1 missions to the Black Sea. We use the NASA Ocean Alt imeter Pathfinder Project colinear data set and monthly climatic hydrograph y to restore the dynamical sea level, that which connected with the Black S ea circulation. Two realizations are created from collinear and grid data s ets. The Black Sea hydrographic survey data collected by the Cooperative Ma rine Science Programme for the Black Sea are used for validation of both pr oducts. The estimated rms accuracy of the Black Sea dynamical level is abou t 3 cm. The grid data product is used for the analysis of seasonal and meso scale variability of the Black Sea level. The observations show that the Bl ack Sea circulation has strong seasonal variation. It attenuates in summer to autumn and intensifies in winter to spring. This variability is accompan ied by a western-phase propagation of the sea level. A simple two-layer mod el of the wind-induced circulation in the rectangular basin provides an int erpretation of these results. It is shown that the seasonal variability of the geostrophic circulation is most likely produced by the annual changes o f the wind stress curl. The western phase propagation is treated as the rad iation of Rossby waves from the eastern coast of the basin. Typical periods of the mesoscale oscillations of the dynamical sea level are estimated fro m the TOPEX/Poseidon altimeter time series in different parts of the Black Sea by means of a spectral analysis. The strongest mesoscale oscillations h ave periods of about 120 days and are located in the southeastern part of t he basin, where the Rim Current bifurcates, and off the Crimean peninsula, where the Rim Current meanders as a result of the local orography.