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| Titel |
Classification of regimes of internal solitary waves transformation over a shelf-slope topography |
| VerfasserIn |
Kateryna Terletska, Vladimir Maderich, Tatiana Talipova, Igor Brovchenko, Kyung Tae Jung |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101343
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| Publikation (Nr.) |
 EGU/EGU2015-463.pdf |
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| Zusammenfassung |
| The internal waves shoal and dissipate as they cross abrupt changes of the topography in the
coastal ocean, estuaries and in the enclosed water bodies. They can form near the coast
internal bores propagating into the shallows and re-suspend seabed pollutants that may
have serious ecological consequences. Internal solitary waves (ISW) with trapped
core can transport masses of water and marine organisms for some distance. The
transport of cold, low-oxygen waters results in nutrient pumping. These facts require
development of classification of regimes of the ISWs transformation over a shelf-slope
topography to recognize ’hot spots’ of wave energy dissipation on the continental
shelf.
A new classification of regimes of internal solitary wave interaction with the shelf-slope
topography in the framework of two-layer fluid is proposed. We introduce a new
three-dimensional diagram based on parameters α ,β , γ. Here α is the nondimensional wave
amplitude normalized on the thermocline thickness α = ain/h1 (α > 0), β is the
blocking parameter introduced in (Talipova et al., 2013) that is the ratio of the height
of the bottom layer on the the shelf step h2+ to the incident wave amplitude ain,
β = h2+/ain (β > -3), and γ is the parameter inverse to the slope inclination
(γ > 0.01).
Two mechanisms are important during wave shoaling: (i) wave breaking resulting in
mixing and (ii) changing of the polarity of the initial wave of depression on the slope. Range
of the parameters at which wave breaking occurs can be defined using the criteria, obtained
empirically (Vlasenko and Hutter, 2002). In the three-dimensional diagram this criteria is
represented by the surface f1(β,γ) = 0 that separates the region of parameters where
breaking takes place from the region without breaking. The polarity change surface
f2(α,β) = 0 is obtained from the condition of equality of the depth of upper layer h1 to the
depth of the lower layer h2. In the two-layer stratification waves of depression may be
converted to wave of elevation at the ’turning point’ (h2 = h1) as they propagate from deep
water onto a shallow shelf.
Thus intersecting surfaces f1 and f2 divide three-dimensional diagram into four zones.
Zone I located above two surfaces and corresponds to the non breaking regime. Zone II lies
above ’breaking’ surfaces but below the surface of changing polarity and corresponds to
regime of changing polarity without breaking. Zone III lies above surface of changing
polarity but below ’breaking’ surfaces and corresponds to regime of wave breaking without
changing polarity. Zone IV that located below two surfaces and corresponds to the regime of
wave breaking with changing polarity.
Regimes predicted by diagram agree with results of numerical modelling, laboratory
and observation data. Based on the proposed diagram the regions in α, β, γ space
with a high energy dissipation of ISW passed over the shelf-slope topography are
distinguished.
References
Talipova T., Terletska K., Maderich V, Brovchenko I., Jung K.T., Pelinovsky E. and
Grimshaw R. 2013. Internal solitary wave transformation over the bottom step: loss of
energy. Phys. Fluids, 25, 032110
Vlasenko V., Hutter K. 2002. Numerical Experiments on the Breaking of Solitary
Internal Waves over a Slope-Shelf Topography. J. Phys. Oceanogr., 32 (6), 1779-1793 |
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