A 2-DIMENSIONAL (X-Z) MODEL OF TIDAL STRAINING IN THE RHINE ROFI

Recent observations of the Rhine ROFI system in the North Sea suggest that the dynamics and structure are very variable, due to the fact tha t the system responds very rapidly to changes in the stirring conditio ns due td tides and winds. They also show very strong semi-diurnal var iability, which is the result of the interaction between tidal straini ng and the cross-shore density gradients. This hypothesis is tested us ing a two-dimensional slice model. The model is successful in reproduc ing the qualitative behaviour of the observations, with the semi-diurn al oscillations in stratification of the right amplitude and at the sa me phase of the tidal cycle as the observations. The model also shows the effect of the stratification on generating the cross-shore tidal s hear which then interacts with the main density gradients, hence the s emi-diurnal variability in stratification. The model confirms previous hypotheses that suggest the importance of wind direction in enhancing or suppressing stratification.