Water mass formation in the Black Sea during 1991–1995

The concepts of the formation of Cold Intermediate Water (CIW) in the Black Sea are revisited on the base of numerical simulations with modular ocean model (MOM) for the period July 1991–June 1995 and validated against the data from three basin-wide surveys carried out during the same period. The time of replenishment of Cold Intermediate Layer (CIL) estimated from simulations varies between 5 and 12 years. The regionalization of the rate of cold water mass formation demonstrates that the dynamical control is of utmost importance. The year-to-year variability of that rate could reach about the half of annual mean values, and the magnitude of the interannual signal of the temperature in the core of Cold Intermediate Layer is comparable with the magnitude of the seasonal one. That explains some of the problems with the earlier estimates of formation rates derived from the observation. It is not only the insufficient data coverage in the horizontal, which biased the estimates, but also the undersampling of the seasonal signal in time. Therefore the parallel analysis of model and survey data could give a more objective tool when estimating the temporal variability of water mass formation.