The Mutual Influence of Tidal Constituents in the Presence of Bottom Stress

The mutual influences of tidal constituents under the effect of bottom stress are examined using analytical techniques to linearize the otherwise quadratic characteristic of the stress. In studying the efficiency of these techniques in explaining the interaction of tidal constituents, adjustments are made to the coefficient of friction in terms of model ʹtuningʹ to optimize performance. The compensatory increase in the coefficient of friction, when all the constituents of a real tide are not included in a model, is seen to depend upon the variance of the neglected constituents as a percentage of the total variance of the tide. The results show that although the correction does help to improve the distribution of the principal tide under investigation, it has an inverse effect on the quality of the non-linear constituents. The conclusion then is that in order to obtain a good profile of the tidal regime in a region, it is preferable to include a group of the major harmonic tidal constituents rather than to adjust the coefficient of friction. Nevertheless some insight is given as to the explanation of the difference between the theoretical value of the adjusted coefficient of friction and its value obtained from a model which attempts to simulate a real tide.