This thesis describes the development, modification and refinement of a high-powered hybrid Stratospheric Tropospheric (ST)/meteor radar at the University of Adelaide’s Buckland Park (BP) field station. This thesis also describes the process of statistically comparing results obtained from multiple co-located independent measurement sources. Also included are statistical comparisons made between meteor radars at BP,Darwin, Northern Territory, and Davis Station, Antarctica, with other independent sources of measurement. Previous meteor radar systems have generally been low powered (∼8 kW peak) and as such could only afford low count rates at frequencies of the order of 50 MHz. While it has been shown that the echo detection rate is inversely proportional to frequency to the power of 1.5, the use of lower VHF frequencies within Australia is restricted by government regulations. As such, this has lead to the development of a high powered meteor radar system at 55 MHz which has served to facilitate higher echo rates at this frequency. The aim of improving the echo rate is to improve the statistical accuracy of results generated by the meteor technique. Also presented are descriptions of the meteor radar systems used to provide the data for this study and the basic principles of the meteor technique. Basic descriptions of the other systems and the techniques used to provide data for comparison are also presented. Two key components in the development of the high-powered meteor system are the high-powered all-sky crossed-dipole transmit antenna and the high-powered 1:2 splitter-combiner required to drive the antenna. The antenna was designed using standard equations for Yagi-Uda antenna design found in literature and modeled using the EZNEC modeling programe. After successful modeling, the antenna was prototyped and refined into a low powered version to investigate the antenna’s performance characteristics. Once the performance of the antenna was verified, the process of upgrading the antenna to handle the full output power from a VTX transmitter was performed. This upgrade also spawned the design and development of the highpowered 1:2 splitter-combiner which would be used to feed the high-powered version of the antenna. The successful operation of the high-powered system over several periods of observation has allowed for a more in-depth investigation into the statistical reliability of the meteor technique. Along with the comparison of standard atmospheric parameters, i.e. temperatures and wind velocity, the high-powered system has allowed for the verification of the relationship between echo rate and radar parameters found by McKinley, which is frequently referred to in many papers dealing with meteor observations. Along with the comparisons made with the results from the high-powered meteor radar system at BP, comparisons of atmospheric parameters derived from meteor observations and other techniques were made at Davis Station and Darwin. Of particular interest is the unique comparison of atmospheric winds made at Davis between two independent meteor radar systems and a Medium Frequency (MF) radar. Previous comparison studies have only enjoyed the benefit of having two independent sources of measurement to compare and as such have not allowed for a unique solution to be obtained for the uncertainties of the techniques using the method of Hocking et al. [2001]. Davis Station is unique in that it has two independent meteor radars in addition to a MF radar. This has enabled for the reduction in the number of degrees of freedom in the statistical comparison process, and as such has allowed for unique solutions to be determined for the uncertainties when comparing two independent techniques; i.e. meteor and MF wind comparisons. Atmospheric temperatures in the Mesospheric and Lower Thermospheric (MLT) region were determined through the use of meteor diffusion coefficients and derived atmospheric pressure models at Davis Station, BP and Darwin. Comparisons are made between the meteor technique and other co-located independent measurements. These include; airglow, satellite and falling sphere measurements at Davis Station, airglow and two independent satellite measurements at BP and two independent satellite observations at Darwin. This thesis as a whole demonstrates the successful operation of the highpowered ST/meteor hybrid radar at BP. It also demonstrates the successful comparisons of MLT winds and temperatures made between meteor radar and other independent sources of MLT measurements. The validation of using the high-powered meteor radar at BP coupled with the successful comparison of atmospheric parameters derived using the meteor technique and other forms of MLT observations serves to re-affirm the statistical accuracy and benefit of the meteor technique in observations of the MLT region. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474902 / Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2010

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-11-08T11:09:05Z No. of bitstreams: 1 ROBSON BATISTA DE SOUSA - DISSERTAÇÃO (PPGFísica) 2012.pdf: 22073508 bytes, checksum: 07991b4cdb0e710b093893fcc69708ec (MD5) / Made available in DSpace on 2018-11-08T11:09:05Z (GMT). No. of bitstreams: 1 ROBSON BATISTA DE SOUSA - DISSERTAÇÃO (PPGFísica) 2012.pdf: 22073508 bytes, checksum: 07991b4cdb0e710b093893fcc69708ec (MD5) Previous issue date: 2012-05-16 / Medidas de ventos e de temperatura obtidas por radar meteórico (SKiYMET) em São João do Cariri-PB (7, 4◦S) e em Cachoeira Paulista-SP (22, 7◦S) foram utilizadas para investigar a oscilação de 6, 5 dias na região mesosférica. Os resultados das análises dos dados de vento e de temperatura revelaram a presença da onda de 6, 5 dias em ambas as localidades, em que as atividades máximas ocorreram durante os meses de primavera austral. Os valores das amplitudes e dos comprimentos de onda vertical, determinados a partir das medidas de ventos, para São João do Cariri, foram superiores aos de Cachoeira Paulista. Em ambas as localidades foram verificadas uma modulação da onda de 6, 5 dias pela Oscilação Semi-Anual (SAO) na temperatura mesosférica. De um modo geral, tanto em São João do Cariri, quanto em Cachoeira Paulista, as atividades máximas da onda de 6, 5 dias foram registradas durante a fase para oeste da Oscilação Quase-Bienal (QBO). Entretanto, o conjunto de dados utilizados neste trabalho não são suficientes para estabelecer uma relação conclusiva dos efeitos da QBO na atividade da onda de 6, 5 dias. Em geral, os parâmetros físicos da onda de 6, 5 dias obtidos neste trabalho são compatíveis com os reportados em outras localidades. / Measurements of wind and temperature obtained from SKiYMET meteor radars at São João do Cariri-PB (7.4◦S) and Cachoeira Paulista (22.7◦S) were used to investigate the 6.5-day oscillations in the mesospheric region. The wind and temperature data analysis results revealed the presence of the 6.5-day waves at both sites, in which the maximum activities have occurred during the austral spring months. The amplitudes and vertical wavelength values, estimated from the wind vertical structure phase delay, for São João do Cariri were longer than for Cachoeira Paulista. For the first time, has been observed for both sites that the 6.5-day wave activities display a semi-annual modulation (SAO) in the meteor temperature. In general, the maximum activities of the 6.5-day waves took place during westward QBO wind phase. However, the data series used in this study are not enough to establish a reliable QBO modulation of the 6.5-day wave. In general, the 6.5-day wave parameters obtained in this work are consistent with those reported for other sites.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2017-07-27T11:59:51Z No. of bitstreams: 1 PDF - Chayenne Edna da Silva Rodrigues.pdf: 17429390 bytes, checksum: 0bdef27d89dbb3d103280bf8a69a7fd2 (MD5) / Made available in DSpace on 2017-07-27T11:59:51Z (GMT). No. of bitstreams: 1 PDF - Chayenne Edna da Silva Rodrigues.pdf: 17429390 bytes, checksum: 0bdef27d89dbb3d103280bf8a69a7fd2 (MD5) Previous issue date: 2017-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this study, the winds obtained by meteor radar at São João do Cariri (7.4 S, 35 W) during 2005, 2006, 2007 and 2008 years, and at Cachoeira Paulista (22.7 S, 45.0 W) during 2002, 2003, 2004, 2005, 2006 and 2008, have been used to characterize the dynamics of the mesosphere region over the two sites during the sudden stratospheric warming events on polar stratosphere in the Northern Hemisphere. The wind measurements were subjected to a wavelet spectrum analysis to identify a presence of periodic oscillations. Wave amplitudes were obtained through harmonic analysis by least squares fitting and the 2-day wave momentum fluxes have been estimated from the wind perturbations. The values of the 2-day wave amplitudes and the respective zonal momentum fluxes observed over C. Paulista were higher in the 2003, 2004 and 2006 summers, and over S. J. do Cariri in 2006 summer, when events of SSW Major have occurred. The mean wind behavior it is indicative that the MLT region, during the summer, have been affected by 2-day wave, however, it was not possible to identify pattern associated with the effects of the SSW events on dynamic behavior of the MLT region over two sites. From analyzes, the 2-day wave intensification and their momentum fluxes during years in which SSWs were major, provide additional evidence to stratospheric jet instabilities, which is the main 2-day wave source mechanism in the summer hemisphere. / Nesta pesquisa, estimativas do campo de velocidade dos ventos obtidas por radar meteórico em São João do Cariri (7,4 S, 35 O), durante os anos de 2005, 2006, 2007 e 2008, e em Cachoeira Paulista (22,7 S, 45,0 O), durante os anos de 2002, 2003, 2004, 2005, 2006 e 2008, foram usadas para caracterizar a dinâmica da região da mesosfera sobre ambas as localidades durante eventos de aquecimento abrupto da estratosfera polar do hemisfério norte. As medidas de vento foram submetidas a análise de espectro de ondaletas para identificar a presença de oscilações periódicas. As amplitudes da s ondas foram obtidas através análise harmônica por ajuste de mínimos quadrados e os fluxos de momentum da onda de 2 dias foram estimados a partir das perturbações. Os valores das amplitudes da onda de 2 dias e dos respectivos fluxos de momentum zonais observados em C. Paulista foram maiores nos verões de 2003, 2004 e 2006, e em S. J. do Cariri em 2006, quando ocorreram eventos de SSW fortes. O comportamento do vento médio demostra que a dinâmica da região MLT durante o verão é impactada pela onda de 2 dias, contudo, não foi possível identificar padrão associado a efeitos dos eventos de SSW com o comportamento dinâmico da região MLT sobre as duas localidades, a partir dessas análises. A intensificação da onda de 2 dias e dos fluxos de momentum durante os anos em que ocorreram SSW fortes fornecem indícios de forçamento adicional para instabilidade do jato estratosférico, que é o principal mecanismo de excitação da onda no hemisfério de verão.

The thesis describes the Meteor Platform and the process of real-time web application design and development. The objective is to provide information covering the technology behind real-time web applications and to describe the Meteor application design and development process utilizing the MMSP methodology. First part of the thesis defines what a real-time web application is and describes Node.js platform and javascript frameworks Mojito, Derby and Meteor. The second part deals with Meteor application design and development process and provides information about used architecture and components. The last chapter provides recommendation on Meteor application development and suitability of the framework for various types of applications, as well as utilization of the MMSP methodology for Meteor application development. The main output and benefit of the thesis is the real-time web application Chute Achiever, which can be used for educational purposes. This thesis is the first academic work about Meteor platform published at the University of Economics.

The quasi two-day wave (QTDW) at 82–97km altitude over Collm (51° N, 13° E) has been observed using a VHF meteor radar. The long-term mean amplitudes calculated using data between September 2004 and August 2014 show a strong summer maximum 5 and a much weaker winter maximum. In summer, the meridional amplitude is slightly larger than the zonal one with about 15ms°1 at 91 km height. Phase differences are slightly greater than 90° on an average. The periods of the summer QTDW vary between 43 and 52H during strong bursts, while in winter the periods tend to be more diffuse. On an average, the summer QTDW is amplified after a maximum of 10 zonal wind shear which is connected with the summer mesospheric jet and there is a possible correlation of the summer mean amplitudes with the backgound wind shear. QTDW amplitudes exhibit considerable inter-annual variability, however, a clear relation between the 11 year solar cycle and the QTDW is not found.

Meteor radar observations of mesosphere/lower thermosphere (MLT) daily temperatures have been performed at Collm, Germany since August 2004. The data have been analyzed with respect to long-period oscillations at time scales of 2–30 days. The results reveal that oscillations with periods of up to 6 days are more frequently observed during summer, while those with longer periods have larger amplitudes during winter. The oscillations may be considered as the signature of planetary waves. The results are compared with analyses from radar wind measurements. Moreover, the temperature oscillations show considerable year-to-year variability. In particular, amplitudes of the quasi 5-day oscillation have increased during the last decade, and the quasi 10-day oscillations are larger if the equatorial stratospheric winds are eastward.

In this diploma thesis I focus on the popular science program for children and youth Meteor, which has been regularly broadcast on radio since 1962. In the opening chapter I am introducing the early years of radiotelephony on our territory - how it gets from the microphone to the telephone handset in the Kbelský tent to the obligatory listening to schools. I also explain the purpose of radio and its effort to spread awareness. For the sake of full understanding it was necessary to state the context of the situation of the 60s to which the Meteor was born. Subsequently, I focus on the history of Meteor, who recently celebrated his 55th birthday, his founders, the main features of the show. In the last part I summarize the current situation and present an interview with the current head of Meteor Petr Sobotka.

From the early stages of planetary accretion and differentiation to the geomorphology of planetary surfaces and the evolution of life, fluids play an integral role in shaping planetary bodies. Fluid properties and processes were investigated under a range of planetary conditions through (1) experimental simulations of impact events and petrographic analysis of terrestrial impactites to determine the effects of shock metamorphism on fluid inclusion properties; and (2) numerical thermodynamic equilibrium modeling of aqueous alteration processes on Mars. Results of impact experiments and analyses of fluid inclusions in rocks from the Ries Crater and Meteor Crater indicate that fluid inclusions reequilibrate systematically with increasing shock pressure: stretching and decrepitating under low shock pressure conditions and collapsing at moderate shock pressures. Above the Hugenoit Elastic Limit, fluid inclusion vesicles are destroyed due to plastic deformation and phase transitions within the host mineral. This suggests that impact processing may result in the destruction of fluid inclusions, leading to shock devolatilization of target rocks. In addition, the absence of fluid inclusions in planetary materials does not preclude the presence of fluids on the meteorite's parent body. Thermodynamic modeling of aqueous alteration of basalt under Mars-relevant conditions provides constraints on the conditions under which secondary sulfates are likely to have formed. The results of this study indicate that jarosite is likely to form as a result of water-limited chemical weathering of basalts. Magnesium sulfates are only predicted to form as a result of evaporation. This suggests that in order to form the alteration assemblages recently observed by the Mars Exploration Rover Opportunity at Meridiani Planum, water must have been removed from the system after a geologically short period of time, before fluids came into equilibrium with mafic surface materials and became alkaline. / Ph. D.

No description available.

This thesis details the application of a medium frequency (MF) Doppler radar to observations of meteoroids entering the Earth's atmosphere. MF radars make possible a greater height coverage of the meteor region (70 to 160 km) than conventional meteor radars. However this type of radar has generally been under-utilised for meteor observations, primarily due to the less than ideal radio environment associated with MF systems. This situation demanded selection of the most appropriate radar meteor techniques and in this respect a variety of techniques are evaluated for application at this frequency. The 2 MHz radar system used in this study is located at the Buckland Park research facility (35.6 deg. S, 138.5 deg. E), near Adelaide, South Australia and is operated by the Department of Physics of the University of Adelaide. This radar has the largest antenna of any MF radar with 89 crossed dipoles distributed over an area of about 1 km in diameter. Beam forming is achieved by varying the phase to groups of elements of the array. The array was constructed in the 1960's, and while having several upgrades, a preliminary examination of the array and associated systems indicated that a significant amount of maintenance work would be required to enable the system to be used for meteor observations. It was also apparent that the software used with the radar hardware for atmospheric studies was not suitable for processing meteor data. Thus a major refurbishment of the radar hardware, as well as the development of appropriate software, was initiated. The complete radar system was divided into its constituent components of antenna array, transmitter, receiver and computer systems. The transmitter and receiver systems were examined and various improvements made including increasing total output power and enhancing beam steering capability. Time domain reflectometry (TDR) techniques were extensively used on the antenna array, as many feed cables showed the presence of moisture. New hardware in the form of a portable power combining system was designed, constructed and tested to further increase radar experimental capabilities. Techniques were developed that verified system performance was to specification. Extensive night time observations of sporadic and shower meteor events were made over a two and a half year period. A particular study was made of the Orionids shower as well as other meteor activity on the night of 22 October 2000. Using the upgraded beam swinging features of the array, a narrow radar beam was used to track the shower radiant in an orthogonal sense so as to maximise the number of shower meteors detected. From each echo, various intrinsic meteoroid parameters were determined, including meteor reflection point angle-of-arrival using a five-element interferometer, echo duration and height; meteoroid speeds were determined using the Fresnel phase time technique. Meteor echoes belonging to the Orionids radiant were selected using a coordinate transform technique. The speed was then used as an additional discriminant to confirm the Orionid shower members. A second radiant, observed at a slightly higher declination is classified as also part of the Orionid stream. The sporadic meteor component in the data set was examined and found to exhibit speeds much higher than expected for sporadic meteors at the time of the observations. However, these results are consistent with a selection bias based on meteoroid speed, that is inherent in radar observations. The Orionid observations indicate that the refurbishment of the radar system and the introduction of new software for meteor analysis has been successfully achieved and that radar meteor studies can now be carried out routinely with the Buckland Park 2 MHz radar. Moreover it has been shown for the first time that meteoroid speeds can be determined with a MF radar operating on a PRF as low as 60 Hz. / Thesis (Ph.D.)--School of Chemistry and Physics, 2003.