Abstract
As mentioned already earlier in Chap. 15, Lake of Lugano is a lake system consisting of two large basins and a pond of much smaller size, all connected to one another. In fact, the discharge of the water masses is from the 15 km long Northern basin through the channel of Melide into the roughly S-shaped 17-km long Southern basin and from there through the 500-m long channel of Lavena into the small pond at Ponte Tresa, see Fig. 18.1. The barotropic response of the two large basins has been separately studied as has this response of the lake system as a whole. In the Southern basin, three limnigraphs, positioned at Riva San Vitale, Morcote and Agno, recorded in February 1982 water elevation oscillations with periods of 28 min and less, that could be identified with the eigenperiods of the surface seiches with amplitudes of less than 5 cm. In a further campaign in 1984, current meters were installed in the Channels of Melide and Lavena and it was found that two further longer periodic eigenoscillations were excited which were not discernible in the limnigraph records and could be interpreted as the eigenvalues of the barotropic oscillations of the lake system acting as a coupled (Helmholtz-type) resonator. The structure of the eigenmodes, i.e. the distribution of the surface elevation was relatively simple. As the eigenfrequencies (periods) increased (decreased) the eigenmodes went from simple to complex with the number of nodal lines increasing by one with each higher order mode. Qualitatively this behaviour is akin to that of a rectangular basin with constant depth, so that interpretation of the data by means of theoretical modelling is easy. Deviations of the eigenperiods and structures of the eigenfunctions from those of the rectangle are due to the bathymetry and nothing else.
Keywords
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
This chapter closely follows the article Stocker et al. [33]. When this paper was written Prof. C.H. Mortimer read its first version and, apart from correcting our English wording, gave advise for improvement.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsNotes
- 1.
This chapter closely follows the article Stocker et al. [33]. When this paper was written Prof. C.H. Mortimer read its first version and, apart from correcting our English wording, gave advise for improvement.
- 2.
What is meant here is the baroclinic response beyond the two-layer response. At mid summer stratification the epilimnion depth is 12 m. With a mean depth of 70 m and a relative density difference \(\Delta \rho /\rho = 2.5 \times 1{0}^{-3}\) and \(f = 1.55 \times 1{0}^{-5}\) (s − 1) for ϕ = 42 ∘ , the two-layer internal, Rossby radius of deformation is
$$\begin{array}{rcl}{ R}_{\mathrm{int}}^{(2)} = \sqrt{g{h}_{\mathrm{eq } } \frac{\Delta \rho } {\rho }} \bigg{/}f = 3,559\,\mathrm{m},\quad {h}_{\mathrm{eq}} = \frac{{h}_{1}{h}_{2}} {{h}_{1} + {h}_{2}}.& & \\ \end{array}$$This is larger than the lake width almost everywhere. An analogous estimate for a three-layer model shows that
$$\begin{array}{rcl}{ R}_{\mathrm{int}}^{(3)} \simeq 1,000\,\mathrm{m},& & \\ \end{array}$$which is slightly less than typical half-widths of the lake. So, the rotation of the Earth can be ignored.
- 3.
This statement is correct if the higher baroclinic modes due to the diffusive thermocline are meant and separate density interfaces due to chemically induced layering are not present. In Chap. 15 (Higher order baroclinicity (I)), it was shown that for the Northern basin of the Lake of Lugano large chemocline elevations occurred with only small amplitudes of the thermocline displacements. In the Southern basin of Lake of Lugano no separate chemocline was recorded.
- 4.
- 5.
This discussion is based on the assumption that effects of the rotation of the Earth can be ignored. In this case, static nodal lines replace the amphidromes.
- 6.
A TVDC-model, in which the epilimnion and hypolimnion layers are bounded by their own shore lines would improve on this, but this was not pursued here.
- 7.
For these and further applications, see Chap. 14.
- 8.
See Volume I, Chap. 10.
- 9.
This is an instrument constructed by the workshop of the Versuchsanstalt für Wasserbau, Hydrologie and Glaziologie at ETH Zürich (VAW).
References
Antenucci, J.P., Imberger, J. and Saggio, A.: Seasonal evolution of the basin-scale internal wave field in a large stratified lake. Limnol. Oceanogr. 45, 1621-1638 (2000)
Antenucci, J.P. and Imberger, J.: On internal waves near the high-frequency limit in an enclosed basin. J. Geophys. Res. 106, C10, 22465-22474 (2001) Limnol.Odeanogr. 43, (8), 1780-1795 (1998)
Bäuerle, E.: Die Eigenschwingungen abgeschlossener, zweigeschichteter Wasserbecken mit variabler Topographie. Berichte aus dem Institut für Meereskunde, Kiel, 85, 126p (1981)
Bäuerle, E.: Internal free oscillations in the Lake of Geneva. Ann. Geophysicae, 3, 199–206 (1985)
Bloomfield, P.: Fourier analysis of time series: An introduction. John Wiley, New York (1976)
Bührer, H. and Ambühl, H.A.: Die Einleitung von gereinigtem Abwasser in Seen. Schweiz. Z. Hydrol., 37(2), 347–369 (1975)
Defant, A.: Physical Oceanography. Vol I, Pergamon Press, New York, (1961)
Defant, A.: Physical Oceanography Vol II, Pergamon Press, New York, (1961)
Hollan, E. and Simons, T.J.: Wind-inuced changes of temperature and currents in Lake Constance. Arch. Met. Geophys. Bioklim., A 27, 333–373 (1978)
Horn, W., Mortimer, C.H. and Schwab, D.J.: Wind-induced internal seiches in the Lake of Zürich observed and modelled. Limnol. Oceanogr., 31(6), 1230–1252 (1986)
Hutter, K., Raggio, G., Bucher, C., Salvadè, G. and Zamboni, F.: The surface seiches of Lake of Lugano. Schweiz. Z. Hydr., 44, 455-484 (1982)
Hutter, K., Salvadè, G. and Schwab, D.J.: On internal wave dynamics in the Northern Basin of the Lake of Lugano. Geophys. Astrophys. Fluid Dyn., 27, 299–336 (1983)
Imberger, J. and Parker, G.: Mixed layer dynamics in a lake exposed to spatially variable wind field. Limnol. Oceanogr., 30(9), 473–488 (1985)
Mortimer, C.H.: The resonant responses of stratified lakes to wind. Schweiz. Z. Hydrol., 15, 94–151 (1953)
Mortimer, C.H.: Lake Hydrodynamics. Mitt. Int. V. Theor. Angew. Limnol., 20, 124–197 (1974)
Mortimer, C.H.: Strategies for coupling data collection and analysis with the dynamic modeling of lake motions. In: Lake Hydrodynamics (Eds. W. H. Graf and C. H. Mortimer), Elsevier, Amsterdam, 183–222E (1979)
Mortimer, C.H.: Internal oscillatory response of Lac Léman to wind impulses during 1977/1978 compared with wave models in rotating channels of uniform depth. Comm. Lab. Hydraul., Ecole Polytechnique Fédérale de Lausanne, 50, 1–89 (1983)
Mortimer, C.H. and Horn, W.: Internal wave dynamics and their implications for plankton biology in the Lake of Zürich. Vierteljahresschr. Naturforsch. Ges., Zürich, 137, 299–318 (1982)
Mysak, L.A., Salvadè, G., Hutter, K. and Scheiwiller, T.: Topographic waves in a stratified elliptical basin with application in the basin of Lugano. Phil. Trans. R. Soc. Lond. A, 316, 1–55 (1985)
Ogihara, Y.: Internal Wave Energy Distribution Ph. D. Thesis, University of Western Australia, (1998)
Phillips, O.M.: On spectra measured in an undulating layered medium. J. Phys. Oceanogr., 1, 1–16 (1971)
Raggio, G. and Hutter, K.: An extended channel model for the prediction of motion in elongated homogeneous lakes, Part I: Theoretical introduction. J. Fluid Mech., 121, 231–255 (1982)
Raggio, G. and Hutter, K.: An extended channel model for the prediction of motion in elongated homogeneous lakes, Part II: First order model applied to ideal geometry. Rectangular basins with flat bottom. J. Fluid Mech., 121, 257–281 (1982)
Raggio, G. and Hutter, K.: An extended channel model for the prediction of motion in elongated homogeneous lakes, Part III: Free oscillations in natural basins. J. Fluid Mech., 121, 283–299 (1982)
Rao, D.B.: Free internal oscillations in a narrow, rotating rectangular basin. Mar. Sci. Directorate, Dept. Fish. Environ., Ottawa (Canada), MS-report 43, 391–398 (1977)
Roget, E.: Internal Seiches and Barclinic Currents in Lake Banyoles. Ph. D. Thesis, Autonomous Unuiversity, Barcelona, 287pp. (1992)
Roget, E., Salvadè, G. and Zamboni, F.: Internal seiche climatology in a small lake where transversal and second vertical modes are usually observed. Limnol. Oceanogr. bf 42 (4), 663-673 (1997)
Saggio, A. and Imberger, J.: Internal wave weather in a stratified lake. Limnol. Oceanogr., 43(8), 1780–1795 (1998)
Schwab, D.J.: Internal free oscillations in Lake Ontario. Limnol. Oceanogr., 22, 700–708 (1977)
Smith, B.T., Boyle, J.M., Garbow, B.S., Ikebe, Y., Klema, V.C. and Moler, C.B.: Matrix eigensystem routines.Eispack guides. Lecture Notes in Computer Science, 6, Eds. G. Goos and J. Harmanis, Springer, Berlin, 387p. (1974)
Stocker, K. and Salvadè, G.: Interne Wellen im Luganersee. Interner Bericht Nr. I/85 der Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie an der ETH Zürich (unpublished) (1986)
Stocker, K. and Hutter, K.: Topographic waves in rectangular basins. J. Fluid Mech., 185, 107–120 (1987)
Stocker, K., Hutter, K., Salvadè, G., Trösch, J. and Zamboni, F.: Observations and analysis of internal seiches in the Southern Basin of Lake of Lugano. Ann. Geophysicae, 5B, 553–568 (1987)
Thorpe, S.A.: On the shape of progressive internal waves. Phil. Trans. Roy. Soc. London, A 263, 563–614 (1968)
Thomas, E.A.: Sprungschichtneigung im Zürichsee durch Sturm. Schweiz. Z. Hydrol., 11, 527–545 (1949)
Thomas, E.A.: Auffällige bilogische Folgen von Sprungschichtneigungen im Zürichsee. Schweiz. Z. Hydrol., 12, 5–23 (1950)
Thomas, E.A.: Sturmeinfluss auf das Tiefenwasser des Zürichsees im Winter. Schweiz. Z. Hydrol., 13, 5–23 (1951)
Trösch, J., Salvadè, G. and Stocker, K.: Die Eigenschwingungen der durch den Kanal im Damm von Melide gekoppelten Becken des Luganersees. Schweiz. Z. Hydrol., 49, 16–28 (1987)
Wang, D.P.: Coastal trapped waves in a baroclinic ocean. J. Phys. Oceanogr., 5, 326–333 (1975)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Copyright information
© 2011 Springer-Verlag Berlin Heidelberg
About this chapter
Cite this chapter
Hutter, K., Wang, Y., Chubarenko, I.P. (2011). Observation and Analysis of Internal Seiches in the Southern Basin of Lake of Lugano. In: Physics of Lakes. Advances in Geophysical and Environmental Mechanics and Mathematics, vol 2. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-19112-1_18
Download citation
DOI: https://doi.org/10.1007/978-3-642-19112-1_18
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-19111-4
Online ISBN: 978-3-642-19112-1
eBook Packages: Earth and Environmental ScienceEarth and Environmental Science (R0)