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Thesis (Ph. D., Geography)--University of Idaho, September 2008. / Major professor: Vladimir B. Aizen. Includes bibliographical references (leaves 69-78). Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (M. Sc.)--York University, 1998. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 181-188). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ27341.

Two transport processes are examined. The first addresses the interaction between the stratosphere and the troposphere. We perform the first analyses of stratosphere-troposphere exchange using one-way flux distributions; diagnostics are illustrated in both idealized and comprehensive contexts. By partitioning the one-way flux across the thermal tropopause according to stratospheric residence time τ and the regions where air enters and exits the stratosphere, the one-way flux is quantified robustly without being rendered ill-defined by the short-τ eddy-diffusive singularity. Diagnostics are first computed using an idealized circulation model that has topography only in the Northern Hemisphere (NH) and is run under perpetual NH winter conditions; suitable integrations are used to determine the stratospheric mean residence time and the mass fraction of the stratosphere in any given residence-time interval. For the idealized model we find that air exiting the stratosphere in the winter hemisphere has significantly longer mean residence times than air exiting in the summer hemisphere because the winter hemisphere has a deeper circulation and stronger eddy diffusion. The complicated response of mean residence times to increased topography underlines the fact that flux distributions capture the integrated advective-diffusive tropopause-to-tropopause transport, and not merely advection by the residual-mean circulation. Extending one-way flux distributions to non-stationary flow we quantify the seasonal ventilation of the stratosphere using the state-of-the-art GEOSCCM general circulation model subject to fixed present-day climate forcings. From the one-way flux distributions, we determine the mass of the stratosphere that is in transit from the tropical tropopause back to the troposphere, partitioned according to stratospheric residence time and exit location. We find that poleward of 45N, the cross-tropopause flux of air that has resided in the stratosphere three months or less is 34 ± 10 % larger for air that enters the stratosphere in July compared to air that enters in January. During late summer and early fall the stratosphere contains about six times more air of tropical origin that is destined to exit poleward of 45S/N in both hemispheres, after an entry-to-exit residence time of six months or less, than is the case during other times of year. We find that 51 ± 1 % and 39 ± 2 % of the stratospheric air mass of tropical origin, annually averaged and integrated over all residence times, exits poleward of 10N/S in the NH and SH, respectively, with most of the mass exiting downstream of the Pacific and Atlantic storm tracks. The mean residence time of this air is found to be ~ 5.1 years in the NH and ~ 5.7 years in the SH. The second transport process addresses new diagnostics of tropospheric transport. We introduce rigorously defined air masses as a diagnostic of tropospheric transport in the context of an idealized model. The fractional contribution from each air mass partitions air at any given point according to either where it was last in the planetary boundary layer (PBL), or where it was last in contact with the tropopause. The utility of these air-mass fractions in isolating the climate change signature on transport alone is demonstrated for the climate of a dynamical-core circulation model and its response to a specified heating. For an idealized warming that produces dynamical responses that are typical of end-of-century comprehensive model projections, changes in air-mass fractions are order 10% and reveal the model's climate change in tropospheric transport: poleward shifted jets and surface intensified eddy kinetic energy lead to more efficient stirring of air out of the midlatitude boundary layer, suggesting that in the future there may be increased transport of industrial pollutants to the Arctic upper troposphere. Correspondingly, air is less efficiently mixed away from the subtropical boundary layer. The air-mass fraction that had last stratosphere contact at midlatitudes increases all the way to the surface, in part due to increased isentropic eddy transport across the tropopause. A weakened Hadley circulation leads to decreased interhemispheric transport in the model's future climate.

Climate modeling efforts depend on remote sensing observations of clouds and aerosols in the atmosphere. This dissertation presents a foundation for using three-dimensional (3D) remote sensing techniques to retrieve cloud and aerosol properties in complex cloud fields. The initial research was aimed at establishing a set of single-scattering properties that could be used in subsequent 3D remote sensing applications. A theoretical stability analysis was used to evaluate what information about the particulate scattering material could be determined from in situ radiance and polarization measurements, and particle size and refractive index were retrieved from synthetic measurements with noise levels comparable to those of existing laboratory instruments. Subsequent research focused on the techniques necessary to retrieve 3D atmosphere and surface properties from images taken by an airborne or space-borne instrument. With the goal of using 3D retrieval methods to extend monitoring capabilities to regions with broken cloud fields, we formulated an efficient procedure for using codes that solve the 3D vector radiative transfer equation (VRTE) to adjust atmosphere and surface properties to fit multi-angle/multi-pixel polarimetric measurements of the atmosphere. Taken together, these two bodies of work contribute to ongoing research which focuses on developing new methods for retrieving aerosols in complex 3D cloud fields, and may extend monitoring capabilities to these currently unresolved scenes.

Sudden changes occur where the mean values associated with two adjacent non-overlapping windows of data are anomalously different, and the transition between the window means occurs over a scale that is small relative to the scale of the windows. Positions of sudden changes can be economically retrieved. The sudden change positions demarcate the data in a manner that can be physically interpreted. Associated with this thesis, are data analyses in terms of the scales, positions, and magnitudes of sudden changes in local (window) mean data values. A sudden change ideally includes an anomalously steep small scale gradient that is associated with change on a much larger scale. Preserving this structure when filtering small scale variance requires an adaptive cutoff scale, as constructed in the third study. The filter adapts a local cutoff scale to the scales, locations and relative magnitudes of the local extremes in the Haar transform, which ideally responds to sudden changes. In the fourth study a filter using a variable cutoff scale is applied in order to partition a nine hour time series of wind velocity. The variable cutoff scale filter separated a transport mode from an isotropic small scale mode more cleanly, in terms of traditional statistics, than did a constant cutoff scale filter. Generally, the positions of sudden changes distinguish windows of data. Windows can be centered on the sudden changes or between them. In the fifth study the sudden changes define boundaries of data windows. The within-window data then contains less variance associated with sudden changes, which deterministically occur between adjacent windows. A sampling procedure based on the locations of the sudden changes is applied in the sixth study in an analysis of surface layer measurements. The "non-random" sampling helps to clarify spatial and temporal patterns in samples of the mean wind and the turbulence stress; the "mesoscale effect" is less ambiguous. / Graduation date: 1996

A 50~MHz E-region coherent backscatter radar was designed based on frequency modulated continuous wave (FMCW) radar techniques. This thesis presents the theory behind the FMCW technique and its implementation in a practical radar system. The system was designed and constructed at the University of Saskatchewan and was field tested at a radar site a few kilometres from the university. This thesis demonstrates that an FMCW radar is technically possible and functional as a research tool for E-region coherent backscatter studies. <p>The primary goal of this research is to develop a better understanding of the plasma processes responsible for the radar echoes. FMCW techniques offer a compromise between the pulsed and continuous wave (CW) radar techniques, which have previously been used for E-region experiments. CW techniques provide excellent spectral measurements but are limited in their ability to determine range information. Pulsed techniques offer excellent range resolution but may be limited in their ability to make detailed high resolution Doppler measurements of E-region radar backscatter. The implementation of FMCW techniques provides a simple and effective method of simultaneously obtaining excellent Doppler and range measurements.<p> The use of FMCW techniques is a novel approach to E-region coherent backscatter studies. Data analysis techniques were developed to extract the range and Doppler information from FMCW radar echoes. In the first few months of operation, the radar observed all four typical E-region radar signatures, Type I to Type IV, plus meteor trail echoes. Observations of each type of radar echo are presented, without interpretation, to illustrate the performance of the radar.

A 50~MHz E-region coherent backscatter radar was designed based on frequency modulated continuous wave (FMCW) radar techniques. This thesis presents the theory behind the FMCW technique and its implementation in a practical radar system. The system was designed and constructed at the University of Saskatchewan and was field tested at a radar site a few kilometres from the university. This thesis demonstrates that an FMCW radar is technically possible and functional as a research tool for E-region coherent backscatter studies. <p>The primary goal of this research is to develop a better understanding of the plasma processes responsible for the radar echoes. FMCW techniques offer a compromise between the pulsed and continuous wave (CW) radar techniques, which have previously been used for E-region experiments. CW techniques provide excellent spectral measurements but are limited in their ability to determine range information. Pulsed techniques offer excellent range resolution but may be limited in their ability to make detailed high resolution Doppler measurements of E-region radar backscatter. The implementation of FMCW techniques provides a simple and effective method of simultaneously obtaining excellent Doppler and range measurements.<p> The use of FMCW techniques is a novel approach to E-region coherent backscatter studies. Data analysis techniques were developed to extract the range and Doppler information from FMCW radar echoes. In the first few months of operation, the radar observed all four typical E-region radar signatures, Type I to Type IV, plus meteor trail echoes. Observations of each type of radar echo are presented, without interpretation, to illustrate the performance of the radar.

Thesis (doctoral)--Paris, 1787. / "Ad primum appollinaris laureum consequendum." Head-pieces. Includes bibliographical references.