Thesis (M.Sc.)--York University, 2003. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 98-116). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: LINK NOT YET AVAILABLE.

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Thesis (Ph.D.)--York University, 2006. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 144-148). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://proquest.umi.com/pqdweb?index=1&did=1251892871&SrchMode=1&sid=3&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1195659544&clientId=5220

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Thesis (Ph.D.)--York University, 2006. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 181-195). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19764

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. 71-75). Also available via the World Wide Web.

Simulations of the circulation in the middle atmosphere during northern winter performed with a nonlinear, mechanistic, global circulation model show that the upper mesospheric jet is greatly overestimated and also the position with respect to latitude and height does not correspond to observations. Apart from that also the winter wind reversal in the mesopause region, evoked by breaking gravity waves (GWs), is located too low around 80km, but is observed to be usually around 100 km. These discrepancies are planned to be eliminated by modifying the distribution of GW amplitudes driving the GW parameterization. This distribution is currently based on potential GW energy data derived from GPS radio occultation measurements and has to be replaced by a distribution based on momentum flux estimates applying midfrequency approximation. The results show a weaker mesospheric jet more realistically tilted towards lower latitudes with height. Also the meridional circulation extending from the summer to the winter pole decelerates and less GWs are propagating into the mesosphere. By additionally varying the GW amplitudes in magnitude and time, the wind reversal is shifted upwards and the mesospheric jet is slowed down. / Simulationen der Zirkulation der mittleren Atmosphäre während des nordhemisphärischen Winters unter Verwendung eines nicht-linearen mechanistischen globalen Zirkulationsmodells ergaben beim Vergleich mit Messungen, dass der simulierte, mesosphärische Jet stark überschätzt wird und dessen Position von den Beobachtungen abweicht. Die in der Mesopausenregion einsetzende Windumkehr, hervorgerufen durch brechende Schwerewellen, befindet sich in etwa 80 km anstatt in 100 km. Diese Diskrepanzen sollen eliminiert werden. Hierfür wird die Verteilung der Schwerewellenamplituden, die die Schwerewellenparametrisierung innerhalb des Modells antreibt, am oberen Rand der Troposphäre modifiziert. Diese basiert derzeit auf global beobachteten, zonal gemittelten Daten der potentiellen Energie von Schwerewellen abgeleitet aus GPS Radiookkultationsmessungen und soll durch eine auf Impulsflüssen basierende Verteilung ersetzt werden. Das Modellexperiment zeigt, dass der mesosphärische Jet mit der Höhe in Richtung niedriger Breiten geneigt ist und abgebremst wird. Zudem schwächt die Meridionalzirkulation vom Sommer- zum Winterpol leicht ab und weniger Schwerewellen dringen bis in die Mesosphäre vor. Zusätzlich wird durch zeitliche und unterschiedlich starke Variation der Schwerewellenamplitude die Windumkehr verlagert und der mesosphärische Jet abgebremst.

A Rayleigh-scatter lidar has been in operation at Utah State University (41. 7° N, 111.8 ° W) starting in September 1993 until the present (October 2003). The return profiles from the atmosphere have been analyzed to provide temperature measurements of the middle atmosphere from 45 to 90 km. Various methods of averaging were used to construct a temperature climatology of the region based on these observations. The data analysis algorithm has been critically analyzed to find possible sources of error, and has been compared to an independently derived technique. The resulting temperatures have been compared to other mid-latitude lidars with good agreement. Comparisons were made with temperatures from other ground-based instruments at Bear Lake Observatory. Additional comparisons were carried out with two satellite-based instruments, WINDII and SABER The comparison of individual nights with the SABER instrument produced surprisingly good agreement considering the difference in the two methods. With the basic analysis of the temperature climatology completed in this work, an outline is given for future research and upgrades to the facility.

The Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere satellite images in the nadir at the UV wavelength of 265 nm. The camera array has an approximately 120° along track (2000 km) by 80° cross track (1000 km) field of view at a horizontal resolution of 1 by 2 km in the nadir. The satellite is in a sun synchronous orbit with an approximately noon local time equator crossing. The observed albedo is due to Rayleigh scattered sun light from an altitude of approximately 50 km and sunlight scattered from Polar Mesospheric Clouds (PMC) which occur in the summer mesosphere at 83 km. The goal of the CIPS instrument is to retrieve high horizontal resolution maps of PMC albedo and the mode radius of the particle size distribution. The first manuscript analyzes the uncertainties involved in the retrieval. The ability to infer mode radius from the PMC signal is made significantly harder by the presence of the Rayleigh signal. Much of the difference between PMC signals of different mode radii is also consistent with possible changes in the Rayleigh signal. The signal is decomposed into components which isolate the portion of the PMC signal's dependence on radius which is not consistent with changes in the Rayleigh signal. This isolated component is compared with the measurement noise to estimate and understand the uncertainties in the CIPS retrieval. The presence of the Rayleigh signal is a difficulty in the PMC retrieval, but it is also a valuable data product. The second manuscript highlights the initial findings of a new gravity wave data set developed by the author. The data set provides relative ozone variations at the stratopause with a horizontal resolution of 20 by 20 km. An abundance of gravity wave signatures can be seen in the data which appear to emanate from weather events like thunderstorms and hurricanes as well as orographic sources such as the Andes and the Antarctic Peninsula. The data set fills a gap that presently exists in our observational coverage of gravity waves, so the data set should help significantly in constraining Global Climate Models. / Ph. D.