Mariner 9 and Viking spacecraft observations during the 1970's have provided evidence for planetary-scale wave-like disturbances in the Mars atmosphere. It has been suggested that possible sources of the wave activity are dynamical instabilities (e.g., barotropic and/or baroclinic instabilities). An other candidate source is forced, quasi-stationary planetary waves. In connection with Mars' enormous relief, both mechanical forcing and large-scale thermal contrasts due to spatially varying surface thermal-inertia and albedo patterns should provide a strong source for planetary-wave activity. In this thesis, we attempt to model aspects of the observed wave activity, focusing on forced planetary waves in the wintertime atmosphere of Mars. Our approach is to apply two dynamical models: a linear primitive equations model and a quasi-linear 'wave, mean-flow' model. Both models have spherical geometry and represent deviations from zonal symmetry in terms of Fourier modes. The former model permits a separation of responses to different elements that make up the total forcing mechanism, whereas the latter is used principally to investigate the role forced planetary waves may play in the Mars polar warming phenomenon. Basic states representing relatively 'non-dusty' and 'highly dusty' conditions near winter solstice allow wavenumber-1 and -2 disturbances to propagate meridionally and vertically into the winter jet. Higher wavenumbers are strongly vertically trapped. Stationary waves in the northern and southern extratropics differ strongly in amplitude, phase and horizontal wave pattern. The possibility for near-resonant, long-period modes in Mars' winter atmosphere is also examined. For several wave-amplitude measures and dissipation strengths, dusty low-frequency responses are an order of magnitude larger than non-dusty ones. Wave, mean-flow simulations using wavenumber-1 or -2 forcings indicate north polar warmings can occur for the dusty basic states. The sensitivity (magnitude, location, and time scale) of a simulated warming to the wave forcing and the dissipation strength is investigated. / Graduation date: 1993

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, June 2004. / Thesis advisor(s): Patrick Harr. Includes bibliographical references (p. 73-75). Also available online.

The enhanced potential vorticity gradients along the polar jet serve as a wave guide for trapped Rossby waves. These tropopause level, synoptic scale Rossby waves are of primary importance for weather development at the surface. In particular, extreme weather events have been linked to the existence of overlying upper level meridionally elongated filaments of stratospheric (high potential vorticity) air which form during the breaking of these waves. Motivated by the desire to understand the conditions under which these waves are formed and to improve their predictability, the current thesis discusses one excitation mechanism---the potential vorticity anomaly associated with a hurricane approaching the extra-tropics. / Attention is directed toward the adiabatic interaction of the cyclone with the polar jet before the two features meet. The hurricane's ability to excite Rossby waves is verified from observations of past interactions and theoretical study using a mechanistic model with idealized settings. The nature of the interaction between the cyclone and the polar jet is found to be sensitive to parameters such as the cyclone's radius and PV anomaly. Three different regimes have been identified. It is also concluded that the same parameters have influence on the skill of the Rossby wave prediction. The more intense the cyclone is, the harder it is to accurately predict the response of the polar jet.

No description available.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 206-209).

No description available.

No description available.

Approved for public release; distribution is unlimited. / Large-scale circulations in the 15-25 day period over the western North Pacific during northern summer were determined using the leading modes of a Singular Value Decomposition of 850 hPa winds and outgoing longwave radiation. Composites were constructed to define the wave patterns' structural characteristics. Their evolution is characterized by alternating cyclonic and anticyclonic equatorial anomalies that are linked to anomalous convective activity. Mid-latitude perturbations appear to contribute to the growth of new equatorial disturbances. Variability within the cycle is examined relative to variations in the basic state vertical wind shear and zonal wind convergence or divergence in the region equator-10ðN, 140ðE-160ðE. For the 50 cases in a basic state with easterly vertical wind shear and convergence, westward-moving waves propagate farther northwestward, wavelength contraction is greater, their orientation changes from east-west to southwest-northeast, and waves appear to be coupled with a Southern Hemisphere mid-latitude wave train. For the zonal wind divergence set, wave activity occurs farther eastward, circulations maintain a longer wavelength and more zonal orientation, and linkage with the Southern Hemisphere mid-latitudes is minimal. A statistically-significant relationship exists between the 15-25 day wave phase and tropical cyclone activity. Formation frequency and preferred locations are modulated by the 15-25 day wave. / Lieutenant, United States Navy

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1981. / Includes bibliographical references (p. 210-215).

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1981. / Supervised by Peter B. Rhines. Includes bibliographical references (leaves 210-215).