Ecological study of gas fields in the northern Adriatic. 5. Numerical modelling of the Bora and Scirocco driven currents

Abstract

       The results of the numerical integration using a non-linear levels model are presented. In the model the vertical turbulent exchange is defined with the Level II closure model. The Nihoul form for the vertical turbulent length-scale is accepted in order to describe surface and bottom turbu­lent layer. For the horizontal exchange of momentum the non-linear Smagorinsky diffusion is assumed. The sea-level distribution after longer integration time has the known general features as well as vertically averaged current field. However, it is understood from the presented results that finer structure of the flow without decreasing the horizontal grid step is obtained. The cur­rent intensities are lower than in some previous numerical experiments. It is discussed consider­ing the results of the analysis of the current-meter data and the integration time. Some prelimi­nary results of stratification impact on the wind induced current has been considered too. The main difference in current fields between stratified and homogeneous sea is observable in the sur­face layer. The heat exchange between sea and atmosphere has not been taken into account. In this case the well-mixed surface layer with the very sharp pycnocline is formed. The Richardson number at the pycnocline is near the critical value and the momentum exchange with the deeper layers is very slow. However, after longer integration time, this does not affect essentially the fields of the vertically averaged current and sea-level distribution.