Дисертації з теми "Australian atmosphere"
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1
Zhuang, Haixiong School of Mathematics UNSW. "Parameterisation of atmosphere-ocean surface interactions, with applications to the Australian monsoon." Awarded by:University of New South Wales. School of Mathematics, 2004. http://handle.unsw.edu.au/1959.4/26170.
Повний текст джерелаАнотація:
Atmosphere-ocean and atmosphere-land interactions are important processes which determine the development of monsoon systems. In this study, a new atmosphere-ocean surface interaction scheme, referred to as AOSIS, is developed and verified with observed data. AOSIS, together with ALSIS (Atmosphere-Land Surface Interaction Scheme), is then coupled into CEMSYS4 (Computational Environmental Modelling System) to investigate the influences of atmosphere-ocean and atmosphere-land surface interactions on the Australian Monsoon, especially the monsoon onset, break and withdrawal. Numerical experiments are carried out and the simulations are compared with the NCEP (National Center for Environmental Prediction, America) data. AOSIS is constructed with three basic components, i.e., a two-layer ocean temperature model, a wind-wave model and a surface flux model. We divide the ocean into a mixed layer and a deep layer. However, the depth of the mixed layer is not constant but varies with time, depending on surface wind shear and buoyancy flux. In AOSIS, we adapted the approach of relating the stages of wave development by wave age and proposed a new expression for calculating the ocean surface roughness length, $z_{0m}$, with consideration of waves. We test AOSIS in a stand along mode against the Moana data and the NCEP data. The comparison with the Moana data shows that AOSIS has considerable skill in simulating SST (sea surface temperature) and energy fluxes, with the simulated values in good agreement with observed data. AOSIS is also successful in simulating the warm and cool effects considered in the COARE (Coupled Ocean-Atmosphere Response Experiment) scheme. Comparison with the NCEP data also confirms that AOSIS simulates SST well. AOSIS and ALSIS are then coupled into CEMSYS4. We apply the system to the simulation of SST and surface energy fluxes over the Australian region and compared the results with the NCEP data. It is found that the simulated SST and energy fluxes are in good agreement with the NCEP data. Further, we study the synoptic events of the Australian Monsoon onset, break and withdrawal and examine the impacts of atmosphere-ocean and atmosphere-land surface interactions on such synoptic events.
2
Rudmann, Silvia G., of Western Sydney Hawkesbury University, Faculty of Science and Technology, and Centre for Horticulture and Plant Sciences. "Resource utilization of C4 tropical grasses at elevated CO2." THESIS_FST_HPS_Rudmann_S.xml, 2000. http://handle.uws.edu.au:8081/1959.7/65.
Повний текст джерелаАнотація:
The atmospheric (CO2) partial pressure is expected to continue to increase and the scenario is that the CO2 partial pressure will reach 50-70 Pa during the 21st century.The rise in CO2 will have a direct influence on plant growth and development because CO2 is the primary substrate for photosynthesis.The aim of the studies described in this thesis was to investigate the response of grasses belonging to two subtypes to a range of CO2 partial pressures under conditions where light intensity, water and N supplies were varied.Two species which are naturalized in Australia, Panicum coloratum (NAD-ME) and Cenchrus ciliaris (NADP-ME) were chosen for a series of experiments conducted in matched growth chambers. The response of C4 plants is particularly important for Australia because they dominate the tropical grasslands that occupy 75% of the continent and form the basis for the pasture industry. Following the extensive research conducted in this study, it can be concluded that the inevitable rise in atmospheric CO2 partial pressure will increase the growth of C4 grasses when other resources are not limiting.Growth of C4 grasses will be stimulated to a greater extent under conditions of drought.Doctor of Philsophy (PhD)
3
Kala, Jatin. "Land-atmosphere interactions in Southwest Western Australia." Thesis, Kala, Jatin ORCID: 0000-0001-9338-2965 (2011) Land-atmosphere interactions in Southwest Western Australia. PhD thesis, Murdoch University, 2011. https://researchrepository.murdoch.edu.au/id/eprint/10624/.
Повний текст джерелаАнотація:
The Southwest of Western Australia (SWWA) is a region of extensive land cover change with an estimated 13 million hectares of native vegetation cleared since European settlement. Whilst previous studies have suggested meteorological and climatological implications of this change in land use, no studies have explicitly focussed on the detailed mechanisms behind the impacts of land-cover change on individual meteorological phenomena. This thesis seeks to identify the physical mechanisms inducing changes within the atmosphere by using the Regional Atmospheric Modeling System (RAMS V6.0) to simulate the impact of land use change on meteorological phenomena at different scales and evaluate these model results against high resolution atmospheric soundings, station observations, and gridded rainfall analyses where appropriate. Sensitivity tests show that land-cover change results in an increase in low-level atmospheric moisture advection associated with the southern sea-breeze due to a reduction in surface roughness. It also results in a decrease in convective precipitation associated with cold-fronts and convective clouds associated with the surface heat trough, due to an increase in wind speed, and a decrease in turbulent kinetic energy and vertically integrated moisture convergence within the PBL. Large-eddy simulations further highlight the role of land-cover change and soil moisture, as well as the contributions of surface versus entrainment fluxes on the growth of the PBL and development of convective clouds. These results are discussed within the broader context of the meteorology of the region.
4
Bai, Zhengdong. "Near-Real-Time GPS Sensing of Atmospheric Water Vapour." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16059/1/Zhengdong_Bai_Thesis.pdf.
Повний текст джерелаАнотація:
An important goal in modern weather prediction is to improve short-term weather
forecasts, especially of severe weather and precipitation. However, the ability to
achieve this goal is hindered by the lack of timely and accurate observations of
atmospheric water vapour, which is one of the most poorly measured and least
understood constituents of the Earth's atmosphere due to its high temporal and spatial
variability. This situation is being addressed by the Global Positioning System (GPS)
technology. GPS radio signals are slowed and bent by changes in temperature,
pressure and water vapour in the atmosphere. Traditionally, the GPS signal
propagation delay is considered a nuisance parameter that is an impediment to
obtaining precise coordinates using GPS. Recent development in GPS precise
positioning and orbit determination has enabled the atmospheric parameters to be
determined to a high degree of accuracy on a routine basis, using continuous tracking
data from ground-based GPS receivers.
The aim of this research is to address several critical scientific challenges in
estimating the atmospheric water vapour content in near-real-time (NRT) in
Australia. Contributions are made to the field of GPS meteorology in the following
five areas:
First of all, research efforts were made to develop a technical platform for the
ground-based GPS meteorology studies and demonstration of GPS Precipitable
Water Vapour (PWV) estimation using observations from Australian Regional GPS
Networks (ARGN). Methods of estimation of water vapour from GPS and
radiosonde data have been developed and tested. GAMIT-based GPS data processing
strategies and compare analysis with radiosonde water vapour solutions from the
Australia Upper Air Network (AUAN) were undertaken, providing an effective
technical basis for further studies.
Secondly, the research has developed techniques to allow estimation of atmospheric
water vapour from GPS data and surface meteorological observations collected
around the GPS sites. Ideally a dedicated meteorological sensor is installed adjacent
to the GPS antenna. However, meteorological sensors are normally not installed at
most Australian GPS stations. Installing a new meteorological sensor at each GPS
station would involve additional cost at the level of one-third or half of the geodetic
GPS receiver cost. We have experimentally developed and demonstrated
interpolation methods for making use of hourly collected surface meteorological data
from the Australian Automatic Weather Station (AWS) network operated by the
Bureau of Meteorology (BOM) to estimate atmospheric water vapour.
Thirdly, the research has studied ocean tidal loading and its effects on GPS derived
precipitable water vapour estimates. The periodic motion of the Earth's surface due
to ocean loading is one of the largest periodic motions. However, very little work has
been done to quantify their effects on GPS-derived solutions at the GPS sites in the
Australian region surrounded by ocean waters. The research presents the theoretical
analysis and experimental results from the ARGN network, focusing on ocean
loading and its effects on GPS derived precipitable water vapour estimates.
The fourth important effort was the development of techniques for estimating highrate
Slant Water Vapour (SWV) values for future operational meteorological
applications in Australia, including addressing such issues as slant-path delay
recovery from post-fit double-difference residuals, and overcoming site multipath
effects. The experimental results have demonstrated the efficiency of the proposed
methods.
Finally, in order to address the meteorological applications with the existing and
anticipated GPS reference stations in the Australian region, and measure the
atmospheric water vapour content in near-real-time, the technical issues to
implement NRT GPS water vapour estimation were identified and discussed,
including the data requirements for meteorological and climate applications, NRT
data processing and quality control procedures for GPS orbits. The experimental
GPS PWV results from NRT and post data processing are compared and presented.
5
Bai, Zhengdong. "Near-Real-Time GPS Sensing of Atmospheric Water Vapour." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16059/.
Повний текст джерелаАнотація:
An important goal in modern weather prediction is to improve short-term weather forecasts, especially of severe weather and precipitation. However, the ability to achieve this goal is hindered by the lack of timely and accurate observations of atmospheric water vapour, which is one of the most poorly measured and least understood constituents of the Earth's atmosphere due to its high temporal and spatial variability. This situation is being addressed by the Global Positioning System (GPS) technology. GPS radio signals are slowed and bent by changes in temperature, pressure and water vapour in the atmosphere. Traditionally, the GPS signal propagation delay is considered a nuisance parameter that is an impediment to obtaining precise coordinates using GPS. Recent development in GPS precise positioning and orbit determination has enabled the atmospheric parameters to be determined to a high degree of accuracy on a routine basis, using continuous tracking data from ground-based GPS receivers. The aim of this research is to address several critical scientific challenges in estimating the atmospheric water vapour content in near-real-time (NRT) in Australia. Contributions are made to the field of GPS meteorology in the following five areas: First of all, research efforts were made to develop a technical platform for the ground-based GPS meteorology studies and demonstration of GPS Precipitable Water Vapour (PWV) estimation using observations from Australian Regional GPS Networks (ARGN). Methods of estimation of water vapour from GPS and radiosonde data have been developed and tested. GAMIT-based GPS data processing strategies and compare analysis with radiosonde water vapour solutions from the Australia Upper Air Network (AUAN) were undertaken, providing an effective technical basis for further studies. Secondly, the research has developed techniques to allow estimation of atmospheric water vapour from GPS data and surface meteorological observations collected around the GPS sites. Ideally a dedicated meteorological sensor is installed adjacent to the GPS antenna. However, meteorological sensors are normally not installed at most Australian GPS stations. Installing a new meteorological sensor at each GPS station would involve additional cost at the level of one-third or half of the geodetic GPS receiver cost. We have experimentally developed and demonstrated interpolation methods for making use of hourly collected surface meteorological data from the Australian Automatic Weather Station (AWS) network operated by the Bureau of Meteorology (BOM) to estimate atmospheric water vapour. Thirdly, the research has studied ocean tidal loading and its effects on GPS derived precipitable water vapour estimates. The periodic motion of the Earth's surface due to ocean loading is one of the largest periodic motions. However, very little work has been done to quantify their effects on GPS-derived solutions at the GPS sites in the Australian region surrounded by ocean waters. The research presents the theoretical analysis and experimental results from the ARGN network, focusing on ocean loading and its effects on GPS derived precipitable water vapour estimates. The fourth important effort was the development of techniques for estimating highrate Slant Water Vapour (SWV) values for future operational meteorological applications in Australia, including addressing such issues as slant-path delay recovery from post-fit double-difference residuals, and overcoming site multipath effects. The experimental results have demonstrated the efficiency of the proposed methods. Finally, in order to address the meteorological applications with the existing and anticipated GPS reference stations in the Australian region, and measure the atmospheric water vapour content in near-real-time, the technical issues to implement NRT GPS water vapour estimation were identified and discussed, including the data requirements for meteorological and climate applications, NRT data processing and quality control procedures for GPS orbits. The experimental GPS PWV results from NRT and post data processing are compared and presented.
6
Torok, Simon. "The development of a high quality historical temperature data base for Australia /." Connect to thesis, 1996. http://eprints.unimelb.edu.au/archive/00000699.
Повний текст джерела
7
Goldthorpe, Ward Hilary. "Carbon capture and storage and the Australian climate policy framework. /." Connect to thesis, 2009. http://repository.unimelb.edu.au/10187/7058.
Повний текст джерела
8
Bowens-Rubin, Rachel. "Paleomagnetism conglomerate test on Archean conglomerate rock from Jack Hills, Australia." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/114374.
Повний текст джерелаАнотація:
Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-60).
A paleomagnetism study known as a conglomerate test was run on an Archean sandstone conglomerate rock to determine if the sample contained a remnant magnetization from the time of its formation. Twenty-nine clasts from a thin section of the sample were thermally demagnetized up to a temperature of 395°C. The heating revealed two components of magnetization which were unblocked at low and mid temperatures, revealing a magnetic mineralogy of Pyrrhotite.Eight matrix samples were heated to a temperature of 650°C which revealed two components of magnetization at mid and high temperatures, providing evidence for a magnetic mineralogy of Hematite.The direction of measured magnetic moment of the clasts were statistically similar, indicating that the rock failed the conglomerate test and was remagnetized after the rock formed.
by Rachel Bowens-Rubin.
S.B.
9
Simons, Frederik Jozef Maurits 1974. "Structure and evolution of the Australian continent : insights from seismic and mechanical heterogeneity and anisotropy." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8063.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002.Includes bibliographical references (p. 235-261).
In this thesis, I explore the geophysical structure and evolution of the Australian continental lithosphere. I combine insights from isotropic and anisotropic seismic surface-wave tomography with an analysis of the anisotropy in the mechanical properties of the lithosphere, inferred from the coherence between gravity anomalies and topography. With a new high-resolution waveform tomographic model of Australia, I demonstrate that the depth of continental high wave speed anomalies does not universally increase with age, but is dependent on the scale and the tectonic history of the region under consideration. I construct an azimuthally anisotropic three-dimensional model of the Australian upper mantle from Rayleigh-wave waveforms. I compare Bayesian inverse methods with discretely parameterized regularization methods, and explore the use of regular, tectonic and resolution-dependent tomographic grids. I advocate the use of multitaper spectral estimation techniques for coherence analysis of gravity and topography, applied to Australian isostasy. I investigate the importance of internal loading, the directional anisotropy of the gravitational response to loading, and the estimation bias affecting the long wavelengths of the coherence function. I develop a method for non-stationary coherence analysis which enables a complete characterization of continental strength by the dependency of gravity-topography coherence on wavelength, direction and geologic age. Combining high-resolution, depth-dependent anisotropy measurements from surface-wave tomography with the mechanical anisotropy from gravity/topography coherence, I assess the validity of two competing theories regarding the cause of continental anisotropy (vertically coherent deformation or simple asthenospheric flow) quantitatively for the very first time.
by Frederik Jozef Maurits Simons.
Ph.D.
10
Shams, Md Shamim. "Improving streamflow forecasting lead-time for Australian rivers using oceanic-atmospheric oscillations and hydroclimatic variables." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/88140.
Повний текст джерелаАнотація:
It is essential to develop a long-lead streamflow forecast system for providing the prior signal for possible floods. Climatic variabilities such as oceanic-atmospheric global oscillations may possess tele-connectivity with Australian rainfall-runoff. This study identifies an ocean-atmospheric region connected with Australian rivers streamflow. By utilizing its persistence capacity, statistical and machine learning-based forecast models are developed, predicting inter-annual streamflow forecast of Australian river flows. This outcome will be beneficial for future water planning and mitigating flood risk.
11
Agustan. "Strategies for estimating atmospheric water vapour using ground-based GPS receivers in Australia." Thesis, Curtin University, 2004. http://hdl.handle.net/20.500.11937/1728.
Повний текст джерелаАнотація:
The Global Positioning System (GPS) of navigation satellites was first developed for global navigation and position determination purposes. Signals from satellites are delayed by the Earths neutral atmosphere on propagating to ground-based receivers, termed the tropospheric delay. Although an unwanted term for precise positioning, the tropospheric delay may be converted to atmospheric water vapour, which is a vital parameter for weather forecasting.This research investigates the optimum GPS processing strategy to estimate atmospheric water vapour derived from ground-based GPS receivers particularly in the Australian region. For this purpose, GPS data observations from GPS permanent stations across Australia, mainly from the Australian Regional GPS Network, will be processed using scientific GPS software in post-processed mode and near real-time mode.This research shows that by applying high accuracy GPS data processing, the tropospheric delay could be estimated precisely. The quality of GPS data processing is indicated by the station coordinates repeatability since the coordinates can gauge at least a coarse assessment of the ability of the processing method to estimate the tropospheric delay.The precipitable water can be estimated from the wet component after separating the tropospheric delay into dry and wet components. High accuracy GPS data processing is dependent on the best choice of processing strategies, and the correct application of error-correction models and a priori constraints. This research finds that the GPS- PW estimation agrees with Radiosonde-PW estimation with an average of standard deviation at 2.5mm level for post-processed strategy and 2.8mm for near real-time strategy. The standard deviation of tropospheric parameter estimates is 1.1mm for post-processed strategy and 1.5mm for near real-time strategy.
12
Agustan. "Strategies for estimating atmospheric water vapour using ground-based GPS receivers in Australia." Curtin University of Technology, Department of Spatial Sciences, 2004. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=15319.
Повний текст джерелаАнотація:
The Global Positioning System (GPS) of navigation satellites was first developed for global navigation and position determination purposes. Signals from satellites are delayed by the Earths neutral atmosphere on propagating to ground-based receivers, termed the tropospheric delay. Although an unwanted term for precise positioning, the tropospheric delay may be converted to atmospheric water vapour, which is a vital parameter for weather forecasting.This research investigates the optimum GPS processing strategy to estimate atmospheric water vapour derived from ground-based GPS receivers particularly in the Australian region. For this purpose, GPS data observations from GPS permanent stations across Australia, mainly from the Australian Regional GPS Network, will be processed using scientific GPS software in post-processed mode and near real-time mode.This research shows that by applying high accuracy GPS data processing, the tropospheric delay could be estimated precisely. The quality of GPS data processing is indicated by the station coordinates repeatability since the coordinates can gauge at least a coarse assessment of the ability of the processing method to estimate the tropospheric delay.The precipitable water can be estimated from the wet component after separating the tropospheric delay into dry and wet components. High accuracy GPS data processing is dependent on the best choice of processing strategies, and the correct application of error-correction models and a priori constraints. This research finds that the GPS- PW estimation agrees with Radiosonde-PW estimation with an average of standard deviation at 2.5mm level for post-processed strategy and 2.8mm for near real-time strategy. The standard deviation of tropospheric parameter estimates is 1.1mm for post-processed strategy and 1.5mm for near real-time strategy.
13
Syarif, Laode Muhamad. "The implementation of international responsibilities for atmospheric pollution : comparison between Indonesia and Australia." Thesis, Queensland University of Technology, 1999.
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14
Myers, Elise McKenna. "Complex lipids in microbial mats and stromatolites of Hamelin Pool, Shark Bay, Australia." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/114126.
Повний текст джерелаАнотація:
Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 44-50).
Stromatolites, columnar rock-like structures, are potentially some of the oldest, microbially mediated fossils visible in the rock record; if biogenesis is able to be confirmed for these ancient stromatolites, some being greater than 3 billion years old, these ancient stromatolites could be used to demonstrate the microbial community assemblages throughout ancient time. Hamelin Pool, Shark Bay, Australia is an ideal field site for this task, as stromtolites and modern microbial mats coexist and the microbial mats have been shown to contribute to the formation of the stromatolites. Comprehensive lipid biomarker profiles were determined in this study for non-lithified smooth, pustular, and colloform microbial mats, as well as for smooth and colloform stromatolites. Intact polar lipids, glycerol dialkyl glycerol tetraethers, and bacteriohopanepolyols were analyzed via liquid chromatography-mass spectrometry (LC-MS) coupled to a Quadropole Time-of-Flight (QTOF) mass spectrometer, while the previously studied fatty acids (Allen et al., 2010) were analyzed using gas chromatography-mass spectrometry (GC-MS) to prove consistent signatures. From the lipid profiles, sulfate-reducing bacteria and anoxygenic phototrophic bacteria and archaea could be inferred. The presence of the rare 3-methylhopanoids was discovered in a significant portion of the samples, which could add to the characterization of this molecule, which has only been concretely linked to oxygenic conditions for formation. In accordance with Allen et al. in 2010, 2-methyhopanoids were detected, as well as limited signals from higher (vascular) plants. While the lipid profiles for all sediment types were similar, there were some differences that are likely attributable to morphological differences. However, the overall similarities suggest microbial communities can be similar between non-lithified microbial mats and stromatolites.
by Elise McKenna Myers.
S.B.
15
Webb, Leanne Beryl. "The impact of projected greenhouse gas-induced climate change on the Australian wine industry /." Connect to thesis, 2006. http://eprints.unimelb.edu.au/archive/00003030.
Повний текст джерела
16
Malinga, Sandile Bethuel. "A comparative study of atmospheric dynamics in the mesosphere and lower thermosphere (MLT) near Grahamstown (South Africa) and Adelaide (Australia)." Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1007307.
Повний текст джерелаАнотація:
The observations made near Grahamstown (33 .3°S, 26.5°E), South Africa and Adelaide (34.5°S, 138.5°E), Australia over the years 1987 to 1994 are used to study the dynamics of the mesosphere and lower thermosphere (ML T) region with a focus on ∼ 90 km altitude. In particular this thesis deals with on the atmospheric mean flow and the solar diurnal and semi diurnal oscillations with a view to (i) deducing their patterns at the two sites, (ii) comparing the dynamic structures observed at the two sites with special emphases on longitudinal variations, and (iii) putting these observations in a global context by comparing with other ground-based observations, satellite observations and numerical simulations. The main findings are summarised below. The mean flow and the tides at Grahamstown and Adelaide are characteristically variable at planetary time scales. Wavelet spectral and multiresolution analyses reveal that the dominant planetary oscillation is the quasi-16-day oscillation. However, no apparent correlation in the 16-day waves of the mean flow, the diurnal tide and the semidiurnal tide was found. The short-term fluctuations were also investigated using complex demodulation and bispectral techniques and it was found that some of the observed variations in tides could be due to non-linear wave-wave interactions. The long-term trends of the mean flow and tides show patterns that are in broad agreement with theory, results from elsewhere (ground-based and satellite) and the results of the Global-Scale Wave Model and various models by Portnyagin and others. In general the mean flow, the amplitudes and phases of both tides were found to exhibit seasonal and interannual variations which are thought to be related to various factors including (i) changes in the atmospheric mean environment, (ii) thermotidal forcing (iii) gravity wave effects, (iv) planetary scale influence, (v) long-term (e.g. quasi-biennial oscillation) modulation, and (vi) solar activity. There are significant longitudinal differences in the dynamic structure between Grahamstown and Adelaide. More especially, Grahamstown tends to have stronger mean flow and tidal activity than Adelaide. For tides, these differences are thought to be partly due to nonmigrating tidal modes but, in general, migrating modes were found to be dominant.
17
Friedmann, S. Julio (Samuel Julio). "Stratigraphy, sedimentology, and tectonic evolution of the 1.86 Ga El Sherana and Edith River Groups, Northern Territory, Australia." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/60422.
Повний текст джерелаАнотація:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.Accompanied by one map on folded leaf in pocket.
Includes bibliographical references (p. 56-61).
by S. Julio Friedmann.
M.S.
18
Doering, Che. "Measurements of the distribution and behaviour of Beryllium-7 in the natural environment." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16513/1/Che_Doering_Thesis.pdf.
Повний текст джерелаАнотація:
Beryllium-7 is a cosmogenic radionuclide produced in the atmosphere through the spallation of nitrogen and oxygen nuclei by cosmic-ray-produced neutrons and protons. It is carried in the atmosphere attached to aerosols and is deposited on land and ocean surfaces by wet and dry deposition processes. Beryllium-7 decays by electron capture to lithium-7 and has a half-life of approximately 53 days. It is a potentially useful radionuclide for studying different natural processes.
This thesis presents a collection of scientific papers on the occurrence of beryllium-7 in the natural environment, particularly in the Southeast Queensland region of Australia. It shows the results of experimental measurements and discusses their implications. Overall, this thesis contributes to advancing our understanding of the distribution and behaviour of beryllium-7 in the natural environment and provides a foundation for the development of nuclear techniques for the evaluation of environmental problems.
19
Doering, Che. "Measurements of the distribution and behaviour of Beryllium-7 in the natural environment." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16513/.
Повний текст джерелаАнотація:
Beryllium-7 is a cosmogenic radionuclide produced in the atmosphere through the spallation of nitrogen and oxygen nuclei by cosmic-ray-produced neutrons and protons. It is carried in the atmosphere attached to aerosols and is deposited on land and ocean surfaces by wet and dry deposition processes. Beryllium-7 decays by electron capture to lithium-7 and has a half-life of approximately 53 days. It is a potentially useful radionuclide for studying different natural processes. This thesis presents a collection of scientific papers on the occurrence of beryllium-7 in the natural environment, particularly in the Southeast Queensland region of Australia. It shows the results of experimental measurements and discusses their implications. Overall, this thesis contributes to advancing our understanding of the distribution and behaviour of beryllium-7 in the natural environment and provides a foundation for the development of nuclear techniques for the evaluation of environmental problems.
20
Kurup, Premnadh M. "Secondary students beliefs about, understandings of, and intentions to act regarding the greenhouse effect." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2003. https://ro.ecu.edu.au/theses/1324.
Повний текст джерелаАнотація:
The greenhouse effect (GHE) is a concern to everyone on this planet. To understand the GHE, students and citizens need an understanding of the chemical processes underlying this environmental phenomenon. Citizens need to be scientifically literate in relation to this phenomenon in order to participate in democratic decision-making and to take appropriate actions in their daily lives. As the GHE is a global issue it will require collective and individual actions to prepare for the likely climatic changes and to reduce the further impact of the GHE. This study focused on high school students' beliefs about, understandings of the GHE and their intentions to act in ways that would reduce greenhouse gas emissions. Aspects of the GHE that are taught in high school science were also investigated. The study was conducted in five schools each in Western Australia (Australia) and Kerala (India) and data were collected from 438 Year 10 and 12 students representing compulsory and post-compulsory stages of education in both states. Two hundred and thirteen students from Western Australia and 225 students from Kerala completed a questionnaire and a sample of students and heads of science were interviewed. A Propositional Knowledge Statement (PKS) was developed, which is a set of propositions that outline science concepts necessary for an understanding of the GHE in terms of its causes, effects, mechanism and actions that can be taken to reduce greenhouse gas emission. In this study the PKS is considered to be the essential knowledge necessary to interpret the GHE, to take appropriate environmental action, and to make informed decisions as a scientifically literate member of society. The questionnaire and interviews were based on the PKS. The study revealed that high school students strongly believe that the GHE is real and affecting the climate at present and will also affect it in the future. They consider that the GHE is a relatively important social issue and they believe that governments should conduct programmes to raise community awareness and enact strict laws to reduce the release of greenhouse gases. Students' understanding of the GHE is inadequate to make informed decisions and take appropriate environmental actions as a scientifically literate member of society. The majority of students and their families are already taking or are considering taking 10 accepted actions to reduce greenhouse gas emissions by household activities. The majority of students are not prepared to sacrifice their personal comforts or conveniences to reduce greenhouse gas emissions and they have strong reasons for that, however, they believe that governments should enact strict laws to reduce greenhouse gas emissions and should sign the Kyoto protocol. The GHE is not adequately represented in Western Australian and Kerala science and chemistry curricula. The heads of school science departments in Western Australia and Kerala consider that school science should do more to teach the GHE, as it is an important aspect of scientific literacy. An ideal scenario for students’ beliefs about, understanding of the GHE and commitments to take action that would enable individuals and communities to reduce greenhouse gas emission was developed based on the PKS and reports such as lPCC (2001), UNEP (2001), AGO (1999; 2000) and UN (1992). The actual scenario was based on the data from this study. The differences between ideal and actual scenarios were discussed and implications for improving education about the OHE were developed. Information about the curriculum and students' sources of information about the GHE, students' beliefs, understandings and intentions to act were mapped against the theory of reasoned action (Ajzen & Fishbein, 1980).
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Heflin, Kelsey L. "Stabilizing California's Water Supply: A Strategy to Alleviate the Impacts of Drought with Desalination." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/cmc_theses/1262.
Повний текст джерелаАнотація:
California is headed into its fifth consecutive year of drought, and climate change is expected to bring more frequent and severe droughts to the state. The state’s water supply is susceptible to drought as seen from the effects of the current dry period. Besides the clear impacts of drought, there are less obvious environmental, economic, and social costs, such as land subsidence from groundwater overdraft, and the consequences of urban tree and green space loss. As a uniquely climate-independent source, desalinated water can stabilize California’s water supply and lessen some of these drought-related impacts. Although seawater desalination is touted as the most costly and energy-intensive method for augmenting water supply, if implemented in a feasible manner, the technology provides a range of positive benefits for drought-prone California in the long term.
This thesis analyzes the economic and environmental costs of using desalination to mitigate the effects of drought in California. The thesis explores both Australian and Californian desalination facilities as case studies for evaluating the benefits and impacts of using different methods of desalination, in an effort to determine which method would be the most beneficial for securing California’s water supply. It concludes that lower-capacity, flexible desalination facilities would be useful along California’s coast, under some conditions. By generating a supply of desalinated water for coastal communities, more water from the state and federal water projects could be redirected to agricultural regions and inland communities that suffer the most from dry spells, and thereby lessen a number of drought-related environmental, economic, and social consequences.
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Martin, Paul Craig. "Radiological impact assessment of uranium mining and milling." Thesis, Queensland University of Technology, 2000.
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Holgate, Chiara. "Land-atmosphere interactions and their effect on Australian precipitation." Phd thesis, 2021. http://hdl.handle.net/1885/230386.
Повний текст джерелаАнотація:
The aim of the research presented in this thesis is to determine the influence of land-atmosphere interactions on Australian precipitation, both under average conditions and during drought. This aim is addressed using a combination of statistical and numerical atmospheric water accounting techniques.
The first part of the research examines soil moisture, a key variable that underpins the analysis of land-atmosphere interactions. Due to the range of estimation techniques and variety of applications utilising soil moisture information, numerous data sets are available. This thesis evaluates soil moisture from ground, satellite and model estimates across Australia and identifies data sets suitable to the study of land-atmosphere interactions and other applications.
Soil moisture information was then combined with observations of precipitation to identify where land-atmosphere interactions have a detectable influence on Australian precipitation. Analysing the statistical relationship between soil moisture and subsequent precipitation, the results showed detectable relationships in north and southeast Australia and the importance of scale in interpreting physical relationships with a statistical metric.
With regions of land-atmosphere interaction identified, the next stage of the research quantified the interaction with the precipitation recycling ratio - a measure of how much of a region's precipitation is derived from evaporation in that same region. Precipitation recycling was quantified using a "back-trajectory" model that identified the evaporative moisture sources of Australia's precipitation. Strongest land-atmosphere interactions and recycling were found in the north and southeast of the continent in spring and summer, along with long term trends in regional moisture sources.
The importance of land-atmosphere interaction during drought was the subject of the final stage of the research. Focusing on the Murray-Darling Basin in southeast Australia, the research analysed the sources of moisture supplying precipitation and the degree to which the land surface amplified precipitation anomalies during drought onset, persistence and termination. The results indicate that major droughts were driven by reduced moisture supply from the ocean, as moisture was circulated away from the region, combined with an absence of precipitation-generating mechanisms over land. Droughts terminated when moist easterly flows from the Tasman and Coral Seas strengthened, promoting high precipitation. Terrestrial moisture sources played a secondary role, amplifying precipitation anomalies by less than 6%.
In summary, the research presented in this thesis has determined the influence of land-atmosphere interactions on Australian precipitation, both under average conditions and during drought. The analysis demonstrates that Australian precipitation is predominantly driven by large scale processes transporting marine moisture to the continent for precipitation, with terrestrial moisture sources forming an important contribution to precipitation in the north and southeast of the continent. In the southeast, drought is driven by atmospheric circulation anomalies redirecting ocean moisture away from the region, with land-atmosphere interactions playing a secondary role.
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Peace, Marika. "Coupled fire-atmosphere simulations of three Australian fires where unusual fire behaviour occurred." Thesis, 2014. http://hdl.handle.net/2440/90794.
Повний текст джерелаАнотація:
Predicting where and how a fire will burn is critical information for mitigating the impacts of bushfires and minimising risk at fuel reduction burns. Firefighter entrapments and fatalities occur mostly at fires that display rapid changes or fluctuations in fire activity. In this thesis, I explore several of the factors that lead to rapid changes in fire behaviour. Understanding these factors is necessary in order to produce accurate fire predictions, which are critical for fire-fighter safety and effective operations. Weather is a primary driver of fire activity; consequently, meteorological information is a key input for anticipating fire behaviour. At present, weather forecasts focus on near-surface conditions; but fires and the atmosphere are three dimensional, and dynamical interactions occur that can have a dramatic influence on fire behaviour. However, these fire-atmosphere interactions are poorly understood due to their complex nature and the difficulty of collecting observational data from a bushfire. In order to further understanding of dynamical interactions between a fire and the surrounding atmosphere, we have simulated three Australian fires where unexpected fire activity occurred, using the coupled fire-atmosphere model WRF and SFIRE. The coupled simulations have been run in feedback on and feedback off mode in order to assess the impact that the fires have on their surrounding atmosphere. The results show significant changes to the mesoscale atmospheric structure as result of the energy released by the fire. Computational fire behaviour models are being used by fire managers in real time and this use will grow in the future. The question is, given we know that fires affect the surrounding atmospheric flow; what weather inputs should the fire models of the future use? The Australian fire science community is currently presented with the opportunity and the challenge to design, develop, and implement fire behaviour simulation models that contain appropriate and comprehensive meteorological inputs. The results presented in this thesis are thought provoking for the current approach to fire weather forecasts and for the use and development of computational fire simulations in the future.Thesis (Ph.D.) -- University of Adelaide, School of Mathematical Sciences, 2014
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Sudholz, Tristan William. "Quantifying Australian atmospheric properties for a gamma-ray observatory to operate at energies greater than 10 TeV." Thesis, 2014. http://hdl.handle.net/2440/84759.
Повний текст джерелаАнотація:
Newly proposed ≥ 10 TeV (1 TeV = 10¹² eV) imaging atmospheric Cherenkov technique (IACT) γ-ray experiments will need optimal sites for their construction and operation at energies above 10 TeV. Quantifying the optical properties of Australian atmospheres will be part of a site survey to determine the viability of possible IACT Australian sites. Atmospheric optical properties need to be quantified as a TeV IACT γ-ray array detects Cherenkov radiation that has propagated through the atmosphere within the visible spectrum. For the optimum collection of Cherenkov radiation, sites with the highest optical atmospheric transmission are ideal. Another optical property of concern is the night sky background (NSB) level. NSB photons are a form of background noise that can cause accidental triggering, therefore sites with the lowest levels of NSB are desired. Further information on IACT and the NSB is presented in Chapter 2. The optical properties of the Australian atmosphere which I quantified for the site surveys were the optical transmission and the NSB. The optical transmission was measured through the star extinction coefficient. The star extinction coefficient and the NSB were found through the method of photometry using a Pentax K10D digital single lens reflex (DSLR) camera. Because a Pentax K10D DSLR camera has not previously been used for this purpose, I initially conducted viability tests on its ability to measure the NSB and star extinction coefficients. I will present these results in Chapter 5. Data collected from multiple trips to Fowlers Gap in New South Wales, Australia, were used for this purpose. I will present the results of star extinction coefficient and NSB level measurements in Chapter 6. To further help understand the effects of atmospheric conditions, I have investigated the effects of differing levels of aerosols and the effects of cirrus clouds on the performance of a simulated ≥ 10 TeV IACT γ-ray array. I give more information about simulated IACT γ-ray array's in Chapter 3 and present the results in Chapter 4. The effects of cirrus clouds were investigated as these clouds occur at a similar height to the maximum emission of Cherenkov photons for γ-ray shower energies around 10 TeV.Thesis (M.Sc.) -- University of Adelaide, School of Chemistry and Physics, 2014
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Gunawan, Dodo. "Atmospheric Variability in Sulawesi, Indonesia." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-B0F3-4.
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O'Brien, Christian. "A clockwork climate? an atmospheric history of Northern Australia." Phd thesis, 2011. http://hdl.handle.net/1885/114573.
Повний текст джерелаАнотація:
Weather and climate are truly arresting in Australia's far north. They set the 'Top End' - the northernmost parts of the Northern Territory - apart; not only from 'temperate' Australia, but also from other tropical locales. Weather and climate are integral to the experience of the place. Authoritative histories of the Northern Territory, with justification, routinely discuss its weather and climate. They indicate the ineluctable physical parameters that bound human activity in this region and which also set the stage for the dramas of human history played out there.
In this study weather and climate are the drama. They are the characters, and they are the plot. Elements of the great aerial ocean in which the 'Top End' is immersed - rain, wind and heat - are studied on a variety of time scales. Events are examined: their intensity, duration, chronology and patterns in time. Just as nature and culture are inextricably entwined, so these elements cannot intelligibly be amputated from human experience. To paraphrase US environmental historian William Cronen, this is a study of stories about stories about weather and climate. The third dimension of this history is its interrogation of the cultural biases and philosophical assumptions both underlying and revealed by these stories about weather and climate.
However, this work focuses on one constellation of encounters and responses: those of the colonial invaders. The ideas and (mis)understandings of this group have determined how weather and climate have been seen since colonial times. Now, in the Anthropocene, as the effects of anthropogenic climate change unfold, this understanding is pivotal in dealing with this looming problem. This study is a history of a plausible, coherent misunderstanding.
It is also a history of the northernmost region of the Northern Territory, a history refracted through a different prism to those of its worthy predecessors. Here the subject is the colonial encounter with tropical skies, science in colonial and northern Australia and experience-based efforts to grasp something so foreign to people from temperate environs. It reveals how western ideas of time have distorted understandings of weather and climate. It demonstrates the poor fit of received ideas of seasonality and climate to historical experience. Reflecting on important contingencies of this place between 1800 and 1942, this history situates human experience in the Northern Territory firmly in the global currents of both environmental history and intellectual history.
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Uthairatanakij, Apiradee, University of Western Sydney, of Science Technology and Environment College, and of Science Food and Horticulture School. "Responses of nectarines to atmospheres containing high carbon dioxide concentrations." 2003. http://handle.uws.edu.au:8081/1959.7/28106.
Повний текст джерелаАнотація:
Nectarines suffer low temperature disorders (LTD)when stored for more than 2 - 3 weeks at temperatures below 8 degrees C. LTD take the form of flesh bleeding and browning, loss of juiciness, development of mealiness and failure to ripen normally.It has been shown previously that adding about 15% CO2 to the storage atmosphere at 0 degrees C can delay the development of LTD in some cvv. of peaches and nectarines. The initial aim of this research was to explore the genetic basis of the differences among cultivars in the responses to high CO2.After much investigation, it was shown that both genetic and seasonal factors are involved in the development of LTD in nectarines. The development of LTD is a form of chilling injury since they only occur at temperatures below 8 degrees C. but there was no evidence of of a direct role for ethylene in either causing or delaying LTD. It was proposed that storage at low temperatures causes a metabolic imbalance resulting from changes in the amounts or activities of proteins associated with normal ripening. Proposals were presented to further examine protein expression using storage conditions that affect the rate of development of LTD.Doctor of Philosophy (PhD)
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Luo, Qunying. "Assessment of the possible impacts of future atmospheric change on South Australian wheat production / Qunying Luo." 2003. http://hdl.handle.net/2440/21978.
Повний текст джерелаАнотація:
"March 2003"Bibliography: leaves 195-209.
Systems requirements: IBM PC or compatible; CD-ROM drive.
x, 209, A4 leaves : ill. (some col.) ; 30 cm. + 1 CD-ROM (4 3/4 in.)
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Geographical and Environmental Studies, 2003
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Keywood, Melita. "Origins and sources of atmospheric precipitation from australia: chlorine-36 and major-element chemistry." Phd thesis, 1995. http://hdl.handle.net/1885/9262.
Повний текст джерелаАнотація:
Temporal and spatial variations of major-element and 36Cl chemistry in rainfall
across Australia have been assessed. Bulk precipitation samples were collected from
two arrays over two years at three-monthly intervals: the WE array (10 sites)
extended in a west to east direction from the coast of Western Australia south of
Geraldton, inland to Warburton in Central Australia, and the SN array (8 sites),
extended in a south to north direction from Port Lincoln in South Australia to
Kakadu in the Northern Territory.
The major-element chemistry shows that the main influence en the composition of
precipitation in remote areas of Australia is mixing between seawater and continental
sources. At most sites along the two arrays it is difficult to distinguish between the
separate end-members of this source, except at coastal localities where seawater
dominates the chemistry of precipitation. However, the influence of seawater is also
evident at non-coastal sites in association with favourable synoptic conditions, such
as cold frontal activity in south and western Australia during winter, and monsoonal
activity in northern Australia during summer. The continentally-derived end-member
is most likely composed of resuspended soil/dust material, including salt-lake
and calcareous dune components. In the south of the SN array where
agriculture is intense this continental source variably includes a fertiliser component.
The chemistry of precipitation across Australia is also affected by an acid-base
balance factor, the components of which are derived from natural sources such as
biogenic emissions, biomass burning and lightning flash production. The nature of
the collection program (i.e. samples are exposed to the atmosphere from the time of
deposition to the time of sample retrieval) means biodegradation is also evident in
the collected sample chemistry.
Chlorine-36 is a cosmogenic isotope with a half-life of 301,000 years. This time
frame, combined with the hydrophilic nature of Cl, makes 36Cl useful as a
hydrological tracer. The use of 36Cl as a hydrological tracer however, relies on
predicted models of 36Cl and stable Cl fallout to calculate 36CJ/CJ ratios for recharge
to hydrological systems. The results from this investigation agree with the general
shape of the latitude-dependent theoretical 36Cl fallout curve of Lal and Peters
(1967), but suggests that the curve underestimates the rate of fallout. A revised mean
fallout for the southern hemisphere of 15.4 36CI atomsfm2/s is suggested, and long-term
average predictions of 36CJ fallout rates used to predict the input ratios of
iv
36CIJC1 in hydrological investigations should be increased by a factor of 1.4 for the
southern hemisphere. Further, while stable Cl concentrations in precipitation display
a general exponential decrease with distance from the coast, the nature of this
relationship is geographically variable, and Cl concentrations in precipitation should
be investigated for each study by local direct measurements, a process that is simple
and inexpensive.
The mean 36Cl fallout for the southern hemisphere, calculated from this work is
three times lower than has been measured for precipitation in the northern
hemisphere. The lower southern hemisphere fallout rates reflect the lower rates of
transfer of stratospheric air to the troposphere in the southern hemisphere, which
results from the less dynamic nature of the lower stratosphere in the southern
hemisphere. The mean global 36Cl fallout that incorporates measurements from the
northern hemisphere with the results of this work is calculated to be 25-35
atomsfm2fs, 2-3 times greater than predicted by Lal and Peters (1967). This suggests
that the cross-section for the cosmic-ray production of 36Cl may be underestimated
in their paper.
This work supports the use of 36Cl as a tracer of atmospheric processes. Is
production primarily in the stratosphere suggests that it may trace stratospheric-tropospheric
exchange. Seasonal variations in 36Cl fallouts and 36ClJCl show high
ratios and fallouts during spring, and at some localities, during summer (i.e. the north
of the SN array). The increased spring 36Cl fallouts are attributed to increased
transfer of stratospheric 36Cl to the troposphere that occurs as the tropopause height
increases during the warmer months. High fallouts during summer in the north of
the SN array may be attributed to the direct entrainment of stratospheric air into
cumulus clouds during the monsoonal convection.
Chlorine-36 exists in the stratosphere predominantly as HCl gas (Wahlen et al 1991).
The correlation between 36CJ and N03 and the lack of any relationship between
36Cl, stable Cl and Na concentrations (the latter being entrained as aerosols), suggest
that 36Cl is scavenged from the atmosphere as a gas rather than an aerosol phase.
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Muller, Kerri Louise. "A comparison of methane dynamics between wetlands constructed for wastewater treatment and a natural sedgeland in South Australia." 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phm9585.pdf.
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Muller, Kerri Louise. "A comparison of methane dynamics between wetlands constructed for wastewater treatment and a natural sedgeland in South Australia / Kerri Louise Muller." Thesis, 2001. http://hdl.handle.net/2440/21684.
Повний текст джерелаАнотація:
"Figures, tables and the appendices appear in the volume II".Bibliography: leaves 130-152.
2 v. (152 leaves, [5] leaves of plates; [75] leaves) : ill. (some col.), col. maps ; 30 cm.
Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 2001
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Berry, Sandra. "A study of the relationships between climate, carbon dioxide and the vegetation over the Australian continent at the present and the last glacial maximum." Phd thesis, 2002. http://hdl.handle.net/1885/151234.
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Massey, Rachel Helen. "Landscapes of Participation and Tradition: The Australian Folk Festival as Process and Public Event." Thesis, 2021. https://hdl.handle.net/2440/135373.
Повний текст джерелаАнотація:
Every year, more than eighty self-designated ‘folk festival’ events are staged throughout Australia. Mainly held in regional and rural towns, these are leisure events characterised by the presentation of formal folk music concerts, the staging of folk dance events as well as oral performances, street performance, and both formal and informal opportunities for music-making and folk engagement with a significant emphasis on attendee participation. Australian folk festivals are modern ‘public events’ – grounded phenomena in their own right, with internal structures of intentionality. This thesis draws upon multi-sited fieldwork conducted at fourteen Australian folk festivals spanning three years and five Australian states and territories, including deep involvement on the organising committee of one local festival. Examining and comparing the internal technologies of these events and how these structures create eventmental landscapes and generate folk atmospheres that affect participants’ sensory experience of folk, offers a unique anthropological theoretical insight into festivals as process. Theorising folk festivals as public events and interrogating their logics of design provides an innovative analysis of how folk festival structures operate on individual and community experience of folk practice in Australia and perform folk as a process. Folk process has long been utilised as a method of defining ‘folk’. Folk process refers to the oral transmission of music (and other folk performance) providing continuity between past and present, and in which community selection and variation or evolution by individuals or the community are key aspects. I argue that as an intentional eventmental landscape, the folk festival acts as the primary site of folk process in Australia, and that this process is facilitated and shaped by participant movement within this landscape. I also argue that the concept of oral transmission should be expanded to include bodily transmission, the body-to-body sharing of folk.Thesis (Ph.D.) -- University of Adelaide, School of Social Sciences, 2021
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Ayub, Gohar. "Response of plant respiration to past and future climates." Phd thesis, 2011. http://hdl.handle.net/1885/151524.
Повний текст джерелаАнотація:
Since the industrial revolution, atmospheric CO{u2082} concentrations have increased from below 300 {u00B5}L L{u207B}{u00B9} to the current 387 {u00B5}L L{u207B}{u00B9} , and are likely to rise to 700 {u00B5}L L{u207B}{u00B9} in the coming decades. Associated with the rise in atmospheric [CO{u2082}] have been an increase in global temperatures and the frequency of severe droughts. To predict the impact of climate change on the biosphere, one must understand the effects of a range of abiotic (particularly increasing atmospheric [CO{u2082}], growth temperatures and drought) and biotic (e.g. symbioses with fungi) factors on plant respiration (R) rates. While much is known about effect of climate variables on rates of photosynthesis and plant productivity, little is known about the climate responses of leaf and root R. In this thesis, I sought to understand how a wide environmental envelope that encompasses past and future climate scenarios affects rates of plant R, with particular focus being given to the effects of subambient to elevated atmospheric CO{u2082} concentrations. Additional studies were conducted to assess the main and interactive effects of atmospheric [CO{u2082}] with water availability, differences in growth temperature, and colonization of roots by mycorrhizal fungi. In seeking to understand how past and future climates, particularly atmospheric CO{u2082} concentrations impact on the carbon economy of plants, I conducted two experiments using contrasting plant species: soybean (Glycine max L.) and Sydney Blue Gum Eucalyptus saligna Sm. For soybean, plants were grown in pots and developed in growth cabinets differing in CO{u2082} concentrations. In this study, I combined a functional growth analysis with measurements of photosynthetic and respiratory processes. Crucially, I quantified the impacts of growth under 290, 400 and 700 {u00B5}L L{u207B}{u00B9} atmospheric [CO{u2082}] on root and leaf R (both in light (Rlight; determined using the Kok method) and dark (Rdark), with short-term changes in measurement [CO{u2082}] and [O{u2082}] being used to further explore the relationship between light inhibition of leaf R and photorespiratory flux. My data showed that elevated [CO{u2082}] resulted in higher relative growth rates (RGR). Moreover, in contrast to the inhibitory effect of low [CO{u2082}] on light-saturated photosynthesis, growth [CO{u2082}] had no significant effect on rates of R in both roots and leaves. To further explore the impact of atmospheric [CO{u2082}] on leaf and root R of soybean, I conducted an additional experiment using mycorrhizal and nonmycorrhizal plants under two growth CO{u2082} concentrations [ambient (400 {u00B5}L L{u207B}{u00B9}) and elevated (700 {u00B5}L L{u207B}{u00B9} ) ] . Here, I tested the hypothesis that plants whose roots are colonized by arbuscular mycorrhiza (AM) fungi would exhibit higher rates of photosynthesis and root R than plants whose roots are not colonized by AM fungi.. Surprisingly, there was no significant difference in the relative growth rate (RGR), rate of photosynthesis, leaf or roots R rates, across the four treatment combinations. To establish the effect of past and future climates on leaf R rates on Eucalyptus, I conducted an experiment under glasshouse conditions, which was CO{u2082} and temperature controlled. Plants were raised in pots. Well-watered and drought-treated plants were grown under conditions differing in growth [CO{u2082}] (280,400 and 640 {u00B5}L L{u207B}{u00B9}) and temperature (26 and 30{u00B0}C). Rates of leaf R in both darkness (Rdark) and in the light (Rlight) were measured. Growth [CO{u2082}] and temperature had little impact on area-based rates of Rdark or Rlighb with the latter indicating little thermal acclimation to the 4{u00B0}C difference in growth temperature (it was short term temperature subjection). However, sustained drought resulted in reduced rates of Rdark, Rlight and light-saturated photosynthesis (Asat) , with the inhibitory effect of drought on Asat and Rlight being greater than on Rdark. Finally, my study from both species provided strong evidence that rates of leaf Rlight were lower than those of Rdark, (with light inhibiting leaf R by 17-47%) and that variations in Rlight can be predicted with a high degree of accuracy from knowledge of the underlying rates of Rdark and associated rates of photosynthetic capacity. Collectively, my research findings highlight the main and interactive effects of several important abiotic factors on plant R, with the results providing a novel framework via which rates of Rlight can be predicted using readily available gas exchange parameters.
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Scarr, Mark J. "The use of stomatal frequency from three Australian evergreen tree species as a proxy indicator of atmospheric carbon dioxide concentration." Thesis, 2011. https://vuir.vu.edu.au/16044/.
Повний текст джерелаАнотація:
Increasing atmospheric carbon dioxide concentration ([CO2]) is the main contributing factor to anthropogenically derived global climate change. The impact of climate change upon terrestrial ecosystems is still uncertain. If information can be obtained on how past fluctuations in [CO2] and temperature has affected terrestrial communities this knowledge can increase our understanding as to how future climate change may impact upon modern-day ecosystems.
Foliar stomatal frequency analysis is a proxy-CO2 measure that may provide estimates of atmospheric [CO2] from subfossil or fossil leaf material. Currently, the majority of the research in this field has been conducted on deciduous Northern Hemisphere species including extant and fossil material. Southern Hemisphere fossil species are
currently under-represented in the fossil proxy-CO2 database. The rate of climate change in the Southern Hemisphere is less than that experienced in the Northern
Hemisphere, so using Northern Hemisphere derived training sets to provide Southern Hemisphere CO2 estimates may introduce confounding errors. Therefore, the use of
Southern Hemisphere training sets on Southern Hemisphere fossil material will provide more accurate atmospheric CO2 estimations. This thesis will contribute to the field of knowledge by determining the applicability of three Southern Hemisphere evergreen tree species to be used as potential proxy-CO2 indicator species.
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Pilotto, Louis Stanley John. "Indoor nitrogen dioxide exposure and respiratory illness in children." Phd thesis, 1994. http://hdl.handle.net/1885/142473.
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Hill, Leanne Jodie. "Geochemical and biogeochemical dispersion and residence in landscapes of western New South Wales." Phd thesis, 2004. http://hdl.handle.net/1885/148590.
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Bliss, Sue 1944, University of Western Sydney, College of Arts, and School of Education. "Implementing global and geographical education." 2006. http://handle.uws.edu.au:8081/1959.7/25316.
Повний текст джерелаАнотація:
This portfolio documents the development and application of a new conceptual framework for the effective implementation of Global Education knowledge, perspectives, values and citizenship in the New South Wales Geography curricula for Years 7-8 (Stage 4), Years 9-10 (Stage 5), and Years 11-12 (Stage 6) (Board of Studies, 1998; 1999; 2003), related teaching and learning resources, and pre-service and in-service courses for teachers. The New South Wales Secondary Global Education Project, funded by the Australian Agency for International Development (AusAID), is managed by the researcher for the Geography Teachers’ Association of New South Wales. The researcher, as manager, was required to publish refereed papers and teaching and learning resources. As such, this portfolio represents a synergistic bringing together of scholarly academic work and professional practice.Doctor of Education (Ed. D.)
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Twomey, Callum. "Historical variability of east coast lows (ECLs) and their impact on Eastern Australia’s hydroclimate." Thesis, 2017. http://hdl.handle.net/1959.13/1356112.
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Research Doctorate - Doctor of Philosophy (PhD)The hydroclimate of eastern Australia is highly variable, with a multitude of large-scale climate processes bearing considerable influence on spatial and temporal rainfall characteristics. One phenomenon known for its contribution to rainfall and which operates on daily timescales, are East Coast Lows (ECLs). These intense low-pressure systems which take place over the subtropical east coasts of southern and northern hemisphere continents are typically associated with gale force winds, large seas, storm surges, heavy rainfall and flooding. While ECL impacts are usually seen as negative (e.g. flooding, storm damage etc.), the rainfall associated with ECLs is also very important for urban water security within the heavily populated eastern seaboard of Australia (ESA). This region of Australia contains a high number of city centres which are forecast to undergo disproportionate rates of growth compared to other areas in Australia. As a result, considerable pressure will be placed on water infrastructure and its resilience to climate variability. This thesis investigates the historical variability of ECLs, and their impact on eastern Australia’s hydroclimate, with particular emphasis placed on the ESA. Within the last decade, several comprehensive ECL databases have been developed. Despite this, inconsistencies remain as to what constitutes an ECL. This has hindered our ability to understand these systems and their impacts. In this thesis, we demonstrate that the definition of an ECL should include classification of the various ECL sub-types based on the synoptic-scale environments from which they form. ECL sub-types have different spatial distributions, seasonal cycles, and rainfall characteristics. Consequently, regions of eastern Australia and in particular the ESA, are influenced differently by different ECL sub-types. An investigation of rainfall across Australia and within the ESA suggests that the ESA is different to the rest of Australia and also not homogenous itself. For winter three separate divisions are identified: (i) the most northerly division from Moreton in Queensland (QLD) to the Manning region of New South Wales (NSW); (ii) the Hunter region south to the metropolitan Sydney area; and (iii) from Illawarra (NSW) to Eastern-central Victoria. For summer, autumn, and spring rainfall, two clear divisions are present: (i) the two most northerly divisions identified in winter combined and (ii) and the equivalent of the third and most southerly outlined for winter. The results suggest that the observed spatial inhomogeneity in rainfall across the ESA is at least in part due to ECLs and their sub-types. Though ECLs may only last a few days, they do have the capacity to provide considerable contributions to water storage reservoirs. Approximately one-third of ECL related rainfall occurs in the 48-hours prior to the system entering the Tasman Sea. Furthermore, given the trajectory of sub-types such as Inland Troughs (IT), Continental Lows (CL) and Southern Secondary Lows(SSL), much of this rainfall provides relief to western flowing headwaters, inland of the Great Dividing Range (GDR). An examination of seasonal rainfall contributions reveals that rainfall associated with Easterly Trough Low (ETL) is statistically significant along the central and northern latitudes of the ESA within winter. SSLs are also found to be significant for the southern extent of the ESA and extends its influence into spring, while CLs establish significance across Victoria. On daily time-scales ITs and ex-tropical cyclones are found to have significantly higher rainfall totals than non-ECL sources (and a number of other ECL sub-types) for their regions of preference. However, due to their infrequent nature, this did not translate into significant seasonal contributions, signifying an important difference in what sub-types present a risk to flooding and those, or rather their absence, that present a risk to water security. ECL sub-types and how their variability impact eastern Australia’s hydroclimate is also shown to be affected by large-scale climate processes. Changes in the spatial distribution of ECLs is found to reflect changes in the proportion of ECL sub-types. When in the La Niña phase, the El Niño Southern Oscillation (ENSO) (and its variant ENSO Modoki) tend to shift the spatial distribution of ECLs north. In winter, this also corresponds to an increase in overall ECL activity. This results in more than a 50% increase in ECL related winter rainfall, while similar magnitude of decrease was observed during the El Niño phase. Other mechanisms such as the Indian Ocean Dipole (IOD) were also found to have a considerable influence on the spatial distribution of ECLs and their associated rainfall. During negative IOD conditions, increases in rainfall west of the GDR corresponded to an increase in the proportion of westerly ECLs. Conversely, during positive IOD, ECL rainfall increases within the ESA owing to a change in the proportion of ECL sub-types. This thesis also provides insights into the importance of ECLs and their sub-types to a key streamflow monitoring station within the Hunter region of NSW. As an indicator for inflowpotential to the Grahamstown Dam, ECLs are responsible for 74% of all streamflow ≥ 99th percentile within the Williams River catchment. Likewise, the absence of ECLs is also shown to be associated with times where the Williams River is experiencing its lowest flow rates. The findings of this thesis are significant and demonstrate the influence ECL sub-types have on hydroclimatic variability in eastern Australia. It also reveals that existing climate related risks are different across the ESA and suggests that how those risks change into the future is also likely to be inconsistent across the ESA – and will likely depend heavily on what eventuates in terms of changes to ECL, and the various ECL sub-types and behaviour (e.g. frequency, timing, location, duration, magnitude and sequencing). This reinforces the need for locally relevant and practically useful climate science information and adaptation strategies - as opposed to State- or Countrywide information and adaptation approaches that are commonly used.