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published_or_final_version / Physics / Doctoral / Doctor of Philosophy

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Includes copies of articles co-authored by the author during the preparation of this thesis. Includes bibliographical references (leaves 233-245). A three-field photometer was employed at the University of Adelaide's Buckland Park field site to collect optical observations of the 557.7nm OI and 730nm OH airglow emissions on an almost continuous basis since May 1995 to May 2000, with observations made whenever the moon was not up.

Includes copies of articles co-authored by the author during the preparation of this thesis. Includes bibliographical references. Electronic publication; full text available in PDF format; abstract in HTML format. A three-field photometer was employed at the University of Adelaide's Buckland Park field site to collect optical observations of the 557.7nm OI and 730nm OH airglow emissions on an almost continuous basis since May 1995 to May 2000, with observations made whenever the moon was not up. Electronic reproduction.[Australia] :Australian Digital Theses Program,2001.

To investigate the generation of mesoscale gravity waves from upper-tropospheric jet-front systems, five different life cycles of baroclinic waves are simulated with a high-resolution mesoscale model (MM5 with 10-km grid spacing). The baroclinicity (and the growth rates) of the baroclinic waves differs significantly among these five experiments as a result of using different tropospheric static stability and tropopause geometry for the initial two-dimensional baroclinic jet. After a short initial adjustment, the baroclinic waves in each experiment grow nearly linearly for as long as five days before the final nonlinear growth stage. Vertically propagating mesoscale gravity waves are generated universally in the exit region of the upper-tropospheric jet streaks near the tropopause level at the later stage of quasi-linear growth and the early stage of nonlinear growth of baroclinic waves. The synoptic environments of gravity waves are consistent with previous studies of typical mesoscale gravity waves. The low-stratospheric gravity waves generated from the upper-level jet streak in these experiments have a horizontal wavelength of 75-175 km and an intrinsic frequency 3-10 times of the Coriolis parameter. The intrinsic frequency of these gravity waves appears to be directly correlated with the growth rate and the strength of the baroclinic waves. In general, the faster the growth rate of the baroclinic waves, the higher the intrinsic frequency of the gravity waves. Similar frequencies of the gravity waves are found in experiments with smaller quasi-linear growth rates of baroclinic waves but with significantly different initial tropospheric static stability and tropopause geometry. The residuals of the nonlinear balance equation are used to assess the flow imbalance. It is also suggested that growth of imbalance is directly related to the growth rate of baroclinic waves and thus the frequency of primary gravity waves of interest. Diagnosis of flow imbalance suggests that balance adjustment, as a generalization of geostrophic adjustment, may be responsible for the generation of the gravity waves in the upper-tropospheric jet-front systems.

To investigate the generation of mesoscale gravity waves from upper-tropospheric jet-front systems, five different life cycles of baroclinic waves are simulated with a high-resolution mesoscale model (MM5 with 10-km grid spacing). The baroclinicity (and the growth rates) of the baroclinic waves differs significantly among these five experiments as a result of using different tropospheric static stability and tropopause geometry for the initial two-dimensional baroclinic jet. After a short initial adjustment, the baroclinic waves in each experiment grow nearly linearly for as long as five days before the final nonlinear growth stage. Vertically propagating mesoscale gravity waves are generated universally in the exit region of the upper-tropospheric jet streaks near the tropopause level at the later stage of quasi-linear growth and the early stage of nonlinear growth of baroclinic waves. The synoptic environments of gravity waves are consistent with previous studies of typical mesoscale gravity waves. The low-stratospheric gravity waves generated from the upper-level jet streak in these experiments have a horizontal wavelength of 75-175 km and an intrinsic frequency 3-10 times of the Coriolis parameter. The intrinsic frequency of these gravity waves appears to be directly correlated with the growth rate and the strength of the baroclinic waves. In general, the faster the growth rate of the baroclinic waves, the higher the intrinsic frequency of the gravity waves. Similar frequencies of the gravity waves are found in experiments with smaller quasi-linear growth rates of baroclinic waves but with significantly different initial tropospheric static stability and tropopause geometry. The residuals of the nonlinear balance equation are used to assess the flow imbalance. It is also suggested that growth of imbalance is directly related to the growth rate of baroclinic waves and thus the frequency of primary gravity waves of interest. Diagnosis of flow imbalance suggests that balance adjustment, as a generalization of geostrophic adjustment, may be responsible for the generation of the gravity waves in the upper-tropospheric jet-front systems.

Thesis (Ph. D.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Nov. 27, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Physics, University of Alberta." Includes bibliographical references.