Sea level variations and their dependency on meteorological and hydrological forcing: Analysis of altimeter and surface data for the Black Sea

TOPEX/Poseidon (TIP) altimeter data in the Black Sea are analyzed for almos t 5 years in parallel with available hydrological and meteorological data w ith the aim of studying the water balance and the dependency of sea level o scillations on meteorological and hydrological forcing. This forcing induce s seasonal variations of mean sea level with oscillations of similar to 10- 15 cm. The consistency between satellite and tidal gauge data is demonstrat ed in several coastal locations, and a mean ascending trend of similar to 3 cm yr(-1) is found in the two data sets. The variability in all components of water balance, including the Bosphorus outflow calculated as the differ ence between the fresh water flux and the time rate of sea level change est imated from altimeter data, is analyzed. The T/P data give very clear signa ls in the patterns of amplitudes of oscillations at intraannual, seasonal, and interannual timescales that help in understanding the variability of ci rculation. The intraannual variations are well pronounced on the continenta l slope and shelf and reach highest amplitudes in the areas of Sevastopol a nd Batumi quasi-permanent eddies. The dearest representation of oscillation s with seasonal periodicity exists in the area of Batumi Eddy. This variabi lity is associated with the transition between states with intense cyclonic circulation in winter and weaker (sometimes anticyclonic) circulation in s ummer-fall period, The Sevastopol Eddy is not clearly resolved in the seaso nal variability. The interannual variability has the strongest signature in the area of western gyre and southeastern Black Sea. The analysis of satel lite data supports some earlier studies on the circulation based on dynamic computations and numerical modeling. They make it possible to estimate the amount of water exchanged between coastal and open ocean areas caused by t he time variability in the Ekman drift. The good quality of altimeter data and the high level of signals could ensure more accurate numerical simulati ons by means of data assimilation.