Modelling Interannual Changes in Dense Water Formation on the Northern Adriatic Shelf

Abstract

The paper aims to estimate wintertime thermohaline properties and dense water formation (DWF) dynamics, rates, and transports in the northern and middle Adriatic between 2008 and 2015. The focus has also been directed to the year-to-year differences between two known DWF sites located on the northern Adriatic shelf and in the eastern coastal region. The estimates are based on a high-resolution interannual simulation by Regional Ocean Modelling System, one-way forced by the meteorological Aladin/HR operational mesoscale model, with new river climatology imposed particularly at the eastern Adriatic coast. Substantial interannual variability in wintertime bottom densities has been found, varying for more than 1.0 kg m−3 among years. Such variations are largely associated with the January–February heat losses, while atmospheric preconditioning in November–December seems to have a little effect on the DWF rates. By contrast, salinity is preconditioning the DWF in the eastern coastal site. That has been found relevant for DWF rates during extraordinary winters, as in the case of 2012. Contribution of a coastal site to the overall DWF rates in other years has not been substantial. Finally, a saw-tooth-like pattern in thermohaline time series has been found in observations and reproduced by the numerical model at the bottom of the middle Adriatic depressions.