Ocean Science
www.ocean-sci.net
1812-0784
1812-0792
3
2
2007
10.5194/os-3-179-2007
http://www.ocean-sci.net/3/179/2007/
http://www.ocean-sci.net/3/179/2007/os-3-179-2007.html
http://www.ocean-sci.net/3/179/2007/os-3-179-2007.pdf
179
188
2007-04-26
Tidal modulation of two-layer hydraulic exchange flows
L. M. Frankcombe
l.frankcombe@phys.uu.nl
A. McC. Hogg
Research School of Earth Sciences, The Australian National University, Canberra, Australia
now at: Institute for Marine and Atmosphere Research Utrecht, Department of Physics and Astronomy, Utrecht University, The Netherlands
Time-dependent, two layer hydraulic exchange flow is studied using an
idealised shallow water model. It is found that barotropic time-dependent
perturbations, representing tidal forcing, increase the baroclinic exchange
flux above the steady hydraulic limit, with flux increasing monotonically
with tidal amplitude (measured either by height or flux amplitude over a
tidal period). Exchange flux also depends on the non-dimensional tidal
period, <i>γ</i>, which was introduced by by Helfrich (1995). When tidal
amplitude is characterised by the barotropic flux amplitude, exchange flux is a
monotonic function of <i>γ</i> as predicted by Helfrich (1995).
However, the relationship between the (imposed) free surface amplitude and
flux amplitude is complicated by reflections within the channel and by the
baroclinic response of the two layer system, leading to a non-monotonic
relationship between the height amplitude and <i>γ</i>.
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