Teses / dissertações sobre o tema "Airglow Observations"

Spectroscopic measurements of the night airglow were taken at mid latitude over a period of four months. The use of intensified CCD spectrographs allowed simultaneous data to be taken from 3000Å to 9200Å in 3300 contiguous spectral elements with a resolution (full width at half max.) of 6Å to 15Å. The average intensities for a 6.5 hour integration period on March 16, 1991 of the O₂ Herzberg I, Chamberlain, Herzberg II, and Atmospheric (0-1) emissions were 230 ± 20 R, 80 ± 10 R, 80 ± 40 R, and 350 ± 20 R respectively. For the OH Meinel (9-4), (8-3), (7-2), (7-3), (6-2), (5-1), (4-0) emissions the intensities were 450 ± 50 R, 450 ± 20 R, 90 ± 20 R, 1620 ± 200 R, 970 ± 50 R, 680 ± 15 R, and 190 ± 20 R respectively. The OI 5577Å and 6300Å emissions were 320 ± 10 R and 160 ± 10 R respectively. These simultaneous emission intensities were compared with an atmospheric model which revealed that the O₂(A³Σ, A'³Δ, c¹Σ, b¹Σ) states and the OH(X²Π) state were heavily quenched. Analysis of the vibrational distributions of the O₂(A³Σ, A'³Δ, c¹Σ) states and the OH(X²Π) state, and dynamic intensity fluctuations of their related emission features provided independent confirmation of the conclusion that the O₂(A³ Σ, A'³Δ, c¹Σ) states and the OH(X²Π) state were heavily quenched.

Includes copies of articles co-authored by the author during the preparation of this thesis. Includes bibliographical references (leaves 233-245). A three-field photometer was employed at the University of Adelaide's Buckland Park field site to collect optical observations of the 557.7nm OI and 730nm OH airglow emissions on an almost continuous basis since May 1995 to May 2000, with observations made whenever the moon was not up.

The Auroral Large Imaging System (ALIS) was proposed in 1989 by Åke Steen as a joint Scandinavian ground-based nework of automated auroral imaging stations. The primary scientic objective was in the field of auroral physics, but it was soon realised that ALIS could be used in other fields, for example, studies of Polar Stratospheric Clouds (PSC), meteors, as well as other atmospheric phenomena.

This report describes the design, operation and scientic results from a Swedish prototype of ALIS consisting of six unmanned remote-controlled stations located in a grid of about 50 km in northern Sweden. Each station is equipped with a sensitive high-resolution (1024 x 1024 pixels) unintensified monochromatic CCDimager. A six-position filter-wheel for narrow-band interference filters facilitates absolute spectroscopic measurements of, for example, auroral and airglow emissions. Overlapping fields-of-view resulting from the station baseline of about 50 km combined with the station field-of-view of 50° to 60°, enable triangulation as well as tomographic methods to be employed for obtaining altitude information of the observed phenomena.

ALIS was probably one of the first instruments to take advantage of unintensi- fied (i.e. no image-intensifier) scientific-grade CCDs as detectors for spectroscopic imaging studies with multiple stations of faint phenomena such as aurora, airglow, etc. This makes absolute calibration a task that is as important as it is dificult.

Although ALIS was primarily designed for auroral studies, the majority of the scientific results so far have, quite unexpectedly, been obtained from observations of HF pump-enhanced airglow (recently renamed Radio-Induced Aurora). ALIS made the first unambiguous observation of this phenomena at high-latitudes and the first tomography-like inversion of height profiles of the airglow regions. The scientific results so far include tomographic estimates of the auroral electron spectra, coordinated observations with satellite and radar, as well as studies of polar stratospheric clouds. An ALIS imager also participated in a joint project that produced the first ground-based daytime auroral images. Recently ALIS made spectroscopic observations of a Leonid meteor-trail and preliminary analysis indicates the possible detection of water in the Leonid.

Le cycle des composes de l'hydrogene dans la stratosphere et la mesosphere est etudie a l'aide d'un modele numerique 2d. La premiere partie est consacree a l'etude du bilan de la vapeur d'eau, avec un traitement detaille de sa production par l'oxydation du methane et de l'hydrogene moleculaire. Dans la seconde partie, le mecanisme photochimique et la variabilite saisonniere de l'emission mesospherique de oh dans les bandes de meinel sont abordes d'un point de vue theorique

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

碩士
國立中央大學
太空科學研究所
106
To study the chemistry and composition of the upper atmosphere, we can utilize airglow emissions from the photochemical reactions of the ions in this region. When the atomic oxygen ions distributed in the ionospheric F region experience an energy level transition, visible light with a wavelength of 630.0 nm is released. We used the photometer system built by our team at NCU to perform ground-based observations of airglow over the sky of Taiwan at Lulin Observatory (23.46°N, 120.87°E) during selected night times. Ground-based airglow spectrometer observations throughout 2016 from the Institute of Solar-Terrestrial Physics (ISTP) in Irkutsk, Russia (51.8°N, 103.1°E) are also utilized. [22] We combined the mean values of our observations every 10 minutes with photochemical models based on the formulas derived from the theories of Link and Cogger (1988), Sobral et al. (1993), and Vladislav et al. (2008). With these different methods, we can estimate how the density of oxygen atomic ions varies with time and altitude and compare the results from empirical models with satellite-based observation data from FORMOSAT-3/COSMIC. The airglow brightness values simulated (Unit: volume emission rate) by the empirical GLOW model v0.98 by Solomon (2017) are also applied to validate the effectiveness of the three inversion models used in this research. The tendency and variation of the atomic oxygen ion density calculated by our photochemical models is compared to the ground-based time variation of airglow radiance, electron density observations of FORMOSAT-3/COSMIC, and input variables from GLOW. Similarities and differences are discussed. The pattern of atomic oxygen ion variation resolved by our inversion model will be utilized for further analysis of ionospheric composition variation in the future.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.
Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 7015. Adviser: Gary R. Swenson. Includes bibliographical references (leaves 105-108) Available on microfilm from Pro Quest Information and Learning.

碩士
國立成功大學
物理學系碩博士班
97
The atomic oxygen red line (6300A) is one of the strongest features in the visible nighttime airglow spectrum at low latitudes which comes from dissociative recombination of the molecular oxygens and electrons. In this study, ionospheric airglows in 6300A wavelength observed by the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) on board the FORMOSAT-2 satellite are used to obtain their long term correlation with the global three-dimensional electron density structure obtained by the radio occultation experiment (GOX) of the FORMOSAT-3/COSMIC satellite. The ISUAL observation in low latitudes shows 6300 Å airglow enhancement peaks appeared mainly in equinox. The MSISE and IRI models were used to simulate the ISUAL observation events can be matched reasonably well by the modeling results. But airglows with double peak enhancements can not be explained by the models. The concurrent observations between ISUAL and GOX show the 6300A airglow enhancement occur at locations of stronger electron density in equinox. In June solstice, global electron density becomes weaker together with airglow emission. Monthly correlation between ISUAL 6300A and GOX electron density shows oscillation with period about six months with correlation coefficient peaked in equinox at 0.8 in March, and minimum in solstice at 0.3 in June. The oscillation in correlation is mainly due to seasonal variations in the distribution of electron and O2 densities. In low latitude region, electron density is higher during equinox than during solstice, and O2 density distribution is rather uniform during equinox, but during solstice, O2 density is higher in the summer hemisphere due to more sunlight than in the winter hemisphere. Therefore, the correlation is high in equinox because O2 distribution in low latitude is uniform and can be considered as background and thus the correlation is directly due to electron density. In solstice the O2 distribution becomes nonuniform in low latitudes and thus the correlation between airglows and the electron density is low.

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

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.
Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2010

碩士
國立中山大學
物理學系研究所
88
Abstract In this study, we use a fisheye lens (180o field of view) and Chare-Couple Device to take the all-sky 6300Å airglow images emitting from ionosphere. By analyzing these Images we can study the phenomenon of equatorial plasma depletions (plasma bubble). Plasma bubbles generate above the magnetic equator; and they drift up to higher altitude and spread to higher latitude area along magnetic lines. The all-sky imaging system was operated at Mt. A-Li (23.511oN, 120.823oE). Because this year is the most active time of sunspots in the solar cycle, we expect that we can take mounts of plasma bubble images in this year.