Controls on stratification in the Rhine ROFI system
In: Journal of Marine Systems. Elsevier: Tokyo; Oxford; New York; Amsterdam. ISSN 0924-7963; e-ISSN 1879-1573, meer
Ook verschenen in:Ruddick, K. (1997). Processes in regions of freshwater influence (PROFILE): selected papers from the 27th International Liège Colloquium on Ocean Hydrodynamics, held in Liège, Belgium, on May 8-12, 1995. Journal of Marine Systems, 12(1-4). Elsevier: The Netherlands. 1-326 pp., meer
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| Trefwoorden |
Mixing
Motion > Water motion > Water currents > Coastal currents
Properties > Physical properties > Buoyancy
Stratification
ANE, Nederland, Nederlandse kust [Marine Regions]
Marien/Kust; Zoet water |
| Auteurs | | Top |
- Souza, A.J.
- Simpson, J.H.
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| Abstract |
Stratification in the Rhine ROFI is very variable; the mean water column stability is controlled by the combined effect of tidal, wind and wave stirring which, at times, brings about complete vertical homogeneity. Control by the mixing variables has been elucidated by a regression analysis of mean stratification on the components of the windstress and significant wave height. There is strong partial correlation with all three variables which explains between 56% and 65% of the variance in two time series of observations in October 1990 and September 1992, respectively. During periods of low stirring the water column was observed to re-stratify over the whole inshore region through the relaxation of the horizontal gradients under gravity and with the influence of rotation. Superimposed on the mean stratification there is strong semi-diurnal variation, occurring throughout the stratified region at times of reduced mixing. The amplitude of this semi-diurnal variation is of the same order as the mean stability and frequently results in conditions being mixed or nearly mixed once per tide. This semi-diurnal variation results primarily from cross-shore tidal straining which interacts with the main density gradient to induce stratification. The hypothesis that water column stability is controlled by the combination of these processes has been tested using a reduced physics model which has been successful in reproducing the main features of both the mean and semi-diurnal components of stratification. |
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