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 (M.S. in Systems Engineering)--Naval Postgraduate School, March 2004. / Thesis advisor(s): Bert Lundy. Includes bibliographical references (p. 119-120). Also available online.

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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.

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The analysis of hadronic events in high-energy electron-positron annihilation often relies upon the clustering of individual hadrons into energetic jets. By solving our theory of strong interactions, Quantum Chromodynamics (QCD) perturbatively, we may make theoretical predictions for these multijet configurations. In this thesis we provide some calculational tools which are useful for evaluating terms in the perturbative series beyond leading order. These include a convenient method of dealing with one-loop integrals containing tensor denominators and universal factorization formulae for matrix elements where two particles are unresolved, which are relevant at the 2-loop (next-to-next-to-leading order) level. In particular we concentrate on the case of the next-to-leading order corrections to 4 jet production (and related processes) and apply . our techniques to obtain explicit results in electron-positron annihilation which are then compared with experimental data.

A single tube flow heat exchanger was designed and built to thermally stress Jet A-1 with air-saturated and deoxygenated levels of dissolved oxygen over a range of fuel temperatures, pressures, and flow rates. Liquid samples of thermally degraded Jet A-1 were analyzed using various physical and optical methods to determine which methods were sensitive enough to measure compositional changes in thermally degraded liquid fuel and to correlate these changes to the measured amount of deposits produced. Temperature programmed oxidation (TPO) was shown to be successful in measuring deposit quantity and structure, while UV-visible absorption and UV-visible fluorescence were sensitive enough to quickly measure the relative population growth of large aromatic compounds that lead to deposit formation in thermally stressed Jet A-1.