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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Modelling the seasonal variation of the Florida current

Corry, R. A. January 1985 (has links)
The linear response of a two layer ocean model to a periodic wind stress curl in the presence of bottom topography has been investigated. For periods much less than the time taken for the wind generated baroclinic Rossby waves to pass over the topography (i.e. 'short' periods), the ocean response is primarily that for a homogeneous ocean and thus strongly modified by topography. For periods much longer than this time (i.e. 'long' periods), the Rossby waves compensate for the effect of topography and the non-topographic Sverdrup balance holds. For the Atlantic at 25°N, the long period limit is of the order of years to decades, so at annual period the non-topographic Sverdrup balance is not applicable. Variations in transport can be forced by a wind stress over varying topography, and by the passage of a coastal baroclinic Kelvin wave over varying topography. The relative importance of the above dynamical considerations for the Florida Current can only be determined from a model calculation involving realistic winds, topography and geography. Such a model calculation has been done with observed Bunker wind stress over a two layer ocean. The predicted variation has a Summer maximum and a Fall minimum, in agreement with the measurements of Niiler and Richardson [1973] and more recent STACS data. The one layer model has been forced by monthly means of ATOLL wind stress for the years 1981-1984. The predicted variation was found not to be in agreement with concurrent STACS measurements. A comparison was made between the Bunker winds and the ATOLL winds via various diagnostics. It was found that the meridional component of the wind, which is crucial to the overall Bunker Summer maximum, is of much reduced importance for the ATOLL winds. This could account for the lack of predicted Summer maxima.
42

The effect of topography on ocean flow

Hughes, Christopher William January 1992 (has links)
The rôle which topography plays in constraining ocean flow is investigated in several ways, mostly aimed at application to the Southern Ocean where topography is known to be important. The physics of topographic Rossby waves is discussed in some depth and a description of ocean flow in terms of a sum of topographic normal modes is developed. It is shown that the apparent incompleteness of topographic modes can often be circumvented by including a function which absorbs the nett input of potential vorticity. Some subtle problems with this description are dealt with, and a calculation of topographic modes for the Southern Ocean is presented, which shows that the modes are very localised, making the use of them to describe basin-wide flows difficult. The effect of interactions between stratification and topography is investigated in terms of a quasi-two-dimensional model which deals only with the depth-integrated flow, and the assumptions which go into the model are examined in detail both analytically and by calculating terms of interest from a data set produced by the Fine Resolution Antarctic Model. It is shown that advection of density in the Southern Ocean can be described to a first approximation as being due to a barotropic current with no vertical velocity, the horizontal component of the baroclinic flow producing very little effect. The balance of terms reveals interesting features in the modelled flow in the Southern Ocean, showing the value of this type of analysis. Finally, insight developed in the course of the investigation allows a simple model to be constructed representing the feedback between density advection and forcing due to density gradients. This model is used to provide an explanation for the fact that the FRAM model spins up linearly, where most simple models would predict a component of quadratic behaviour in the spin-up.
43

Modelling of atmospheric stationary long waves

Beaudoin, Christiane Carole January 1974 (has links)
No description available.
44

Observations of long Rossby waves in the northern tropical Pacific /

Kessler, William S., January 1989 (has links)
Thesis (Ph. D.)--University of Washington, 1989. / Vita. Includes bibliographical references.
45

On the propagation of free topographic Rossby waves near continental margins

Ou, Hsien Wang. January 1979 (has links)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979. / Supervised by Robert C. Beardsley. Vita. Includes bibliographical references (leaves 121-122).
46

On the propagation of free topographic Rossby waves near continental margins /

Ou, Hsien Wang. January 1979 (has links)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979. / Supervised by Robert C. Beardsley. Vita. Includes bibliographical references (leaves 121-122).
47

Planetary waves in a polar ocean

LeBlond, Paul Henri January 1964 (has links)
The dynamics of the Arctic ocean are studied on a polar projection of the sphere. The density structure is idealized as a two-layer system, and a general formulation is developed which allows inclusion of latitudinal and longitudinal depth variations as well as asymmetries in the boundaries of the ocean. For simplicity, the density structure is neglected when depth variations are present. Time dependent displacements from equilibrium levels are assumed to be waves of constant zonal wave number; no radial propagation is considered. Amplitude equations are derived for these displacements, subject to the assumption that the polar basin is small enough to keep only a first approximation to the curvature of the Earth. A semi-qualitative investigation of the possible solutions is made in the case of a symmetrical basin, using the Method of Signatures, and existence criteria are found for the solutions in the presence of radial depth variations. Concentrating thereafter on planetary waves, explicit solution for such motions in the simplest case (depth constant, symmetrical boundaries) allows comparison with the results of other investigators (Longuet-Higgins, 1964 b; Goldsbrough, 1914 a) . It is found that the polar projection and first approximation to the curvature give quite good results, so that this method may be applied to polar regions in the same way as the β-plane is used in mid-latitudes. The general effects of radial bottom slopes are discussed and a simple example treated more explicitly. Some theorems of Ball (1963) on the motions of shallow rotating fluids in paraboloidal basins are found to hold for such basins in the polar plane approximation to the sphere. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
48

Modelling of atmospheric stationary long waves

Beaudoin, Christiane Carole January 1974 (has links)
No description available.
49

Asymptotic and numerical solutions of trapped Rossby waves in high-latitude shear flows with boundaries

Harlander, Uwe 28 November 2016 (has links) (PDF)
We consider the amplitudes of coastally trapped Rossby waves in a high-latitude shear flow on a modified ß-plane, where also the effect of the sphericity of the earth (c5-effect) is taken into account. We present a particular analytical solution and also asymptotic and numerical solutions. We find that the asymptotic WKB solutions are accurate compared to the numerical results. We show that the o-effect is most important for shorter waves and leads to an enhanced selection of trapped Rossby wave modes. / Wir betrachten die Amplituden von küstennah gefangenen Rossby-Wellen in einer Scherströmung hoher Breiten. Die Rechnungen werden auf einer modifizierten ß-Ebene durchgeführt, die auch die Spherizität der Erde berücksichtigt (o-Effekt). Wir zeigen eine spezielle analytische Lösung und auch asymptotische und numerische Lösungen. Die asymptotischen WKB-Lösungen erweisen sich als genau, verglichen mit den numerischen Resultaten. Der o-Effekt wirkt sich a stärksten bei den sehr langen und den kurzen Wellen aus und führt zu einer stärkeren Selektion von Moden gefangener Rossby-Wellen.
50

Large-scale dynamics of the upper mesosphere and lower thermosphere / by Trevor Harris.

Harris, Trevor, 1965- January 1993 (has links)
Bibliography : p. 333-342. / xiii, 342 p. : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1994?

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