Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (December 13, 2006) Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 91-106).

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on November 18, 2009). Thesis advisor: Dr. Neil I. Fox. Includes bibliographical references.

Constant volume superpressure pillow balloons were flown over a mountain valley downwind from a sharp ridge line. Balloon trajectories revealed and atmospheric soundings confirmed a persistent turbulently mixed adiabatic layer over the valley at approximately ridge top height except in the immediate lee of the ridge where strong vertical motions were observed. Temporary stationarity of the relative mesoscale turbulence was found to exist on a time scale exceeding 4 hours. Power spectrum analysis of component relative velocities showed greater variance in lower wave numbers and anisotropy in mesoscale turbulence. Eddy diffusivity coefficients for turbulence above the ridge height were Kx= 1×107 , Ky = 5×106 , Kz = 1×106 (cm2 sec-1). Below the ridge line Kz was nearly constant at 2×105 cm2/sec- 1. Kz was found to vary exponentially with R, a balloon-ridge ratio; Kz ∞ exp (3R).

Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Meteorology. / Microfiche copy available in Archives and Lindgren. / Vita. / Bibliography: leaves 175-177. / Sc.D.

No description available.

No description available.

Experiments have been conducted with a two-dimensional timedependent, numerical model of the general circulation of the atmosphere up to the mesopause. A scheme for the calculation of cooling rates due to the 15(mu)m band of carbon dioxide is developed. It uses the Curtis matrix approach which incorporates cooling-to-space, transfer of radiation between atmospheric layers and non-equilibrium effects in the upper mesosphere. The sensitivity of the cooling rate calculations to the choice of collisional relaxation time is investigated. An 'almost exact' scheme to calculate heating rates due to the absorption of solar radiation by ozone and molecular oxygen is presented. Use of both new radiation schemes enables the diabatic heating rate to be calculated to the upper boundary of the model. Other heat sources in the region of the mesopause are discussed. Incorporation of the new schemes considerably improves the modelled temperature structure of:the stratosphere and lower mesosphere. The upper mesosphere is not well reproduced with no indication of the observed cold summer mesopause. The heat and momentum budgets of the mesosphere are studied. Eddy momentum fluxes derived from satellite observations of planetary waves are found to be significant for the circulation and transport properties of the stratosphere but incapable of producing the required distribution of angular momentum in the mesosphere. A Rayleigh friction parameterisation is included in the mesosphere to reproduce the observed zonal wind and temperature structure. Momentum deposition by tides and gravity waves is discussed. Curtis matrices are calculated with higher mixing ratios of carbon dioxide and the effects of increased atmospheric CO2 on stratospheric temperatures and ozone is investigated. Temperature decreases of up to about 10K are predicted with increases in ozone concentration in the upper stratosphere. In the lower stratosphere the ozone increases are restricted to high latitudes and a decrease shown in equatorial regions. The latitudinal variations are reflected in the ozone column density. An experiment is conducted in which chlorofluorocarbons are released into the model atmosphere and the effects on stratospheric ozone are in exactly the opposite sense to those predicted for the CO2 case. A run in which CO2 and CFCs are introduced simultaneously shows that the two effects are not linearly additive. A simple photochemical theory is used to investigate the temperature dependence of ozone and to explain the non-linearity of the coupled experiment.

The dynamical nature of atmospheric disturbances in the Southern Hemisphere simulated by a two-level general circulation (GCM) model is studied. Time series of the dependent variables and diabatic heating components from 10 Southern Hemisphere winters (JJA) and summers (DJF) simulated by the Oregon State University two-level GCM are used. The time mean fields are presented and discussed. Variance and covariance analyses are performed to determine the geographical distribution, intensities and transport properties of high-frequency (periods between 2.5 and 10 days) and low-frequency (periods between 10 days and a season) transient eddies. These are discussed in terms of dynamical consistency with the time-mean circulation. It is found that the behavior of the high-frequency eddies at mid and high-latitudes is consistent with baroclinic instability theory, i.e., the eddies have properties similar to observed migratory weather disturbances. The low-frequency eddies appear to be quasi-stationary Rossby waves originating at middle latitudes. They seem to disperse energy in a manner consistent with arguments based on simple linear wave dynamics. During wintertime, the time mean flow directs eddies poleward where they grow by baroclinic processes. Also during wintertime, the slow phase velocity, fast group velocity and cyclic domain lead to quasi-resonant behavior on a hemispheric scale. / Graduation date: 1988

Intense atmospheric convection associated with the South Pacific Convergence Zone (SPCZ) significantly impacts basin-scale circulation patterns over the Pacific. We explore dynamical processes which foster changes in convection along the convergence zone. These forcings include strong moisture convergence and accumulation of wave energy in the boundary layer, as well as dynamical instability associated with moderate cross-equatorial wind bursts. A focus is applied to observing the dominant modes of variability on synoptic to intraseasonal timescales using a combination of satellite observations and NCEP reanalysis data. Accumulation of energy, due to negative stretching deformation, occurs with both tropical and extratropical modes suggesting that the SPCZ is an artifact of wide ranging modes. Signals of the dominant modes (inferred from fields of outgoing longwave radiation: OLR) are isolated using bandpass filtering techniques, which are then mapped in space and time using Principal Components from Empirical Orthogonal Function analyses. Variability of convective systems in the SPCZ is found to be significantly correlated with changes in the regional Hadley Circulation and the Pacific Walker cell. This co-variability presents the possibility of important teleconnection routes between the tropical West and East Pacific, as well as with the mid-latitude regions of the Northern and Southern Hemispheres. We test these interaction hypotheses by developing composites of the circulation patterns using dates of maximum convection events (regions of minimum OLR) in the SPCZ. Intensities of the large-scale circulations are measured using observations of stream function mass fluxes. Results suggest that deep convection maxima (minima) are associated with an increase (decrease) in the Walker Circulation. It is also illustrated how off-equatorial convection anomalies in the subtropical portion of the SPCZ may induce changes to the Hadley Circulation. Interactions with the zonal (Walker) and meridional (Hadley) circulations appear to have important consequences on the ability for wave energy to propagate through the tropical Pacific atmosphere. Examples include Northern Hemisphere cross-equatorial teleconnections through the Westerly Wind Duct in the upper branch of the Walker circulation and Rossby wave trains in the SPCZ, which may be partially governed by characteristics of the regional Hadley circulation.