"September 2003" / Bibliography: leaves 209-216. / xxvi, 216 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis has introduced a number of enhancements to the PMHT algorithm, motivated by the Over the Horizon Radar tracking problem. The two primary enhancements are the incorporation of classification information, and the introduction of a discrete state model for the assignment prior probability. The modified PMHT algorithms achieved through these enhancements are referred to as PMHT-c and PMHT-y respectively. / Thesis (Ph.D.)--University of Adelaide, School of Electrical and Electronic Engineering, 2003

Includes bibliographical references. Due to the rapid deployment of modern over-the-horizon radars, antenna/sensor position errors may be present and, since the antennas have a simple and cost-effective design, mutual coupling may also be present. These imperfections, which can degrade radar performance, form the basis of the investigation. Also calibrates the receiving array of the Jindalee over-the-horizon radar (located in Central Australia) using echoes from meteor trails.

<p>The main objective of this thesis is to contribute to the understanding of sea ice processes in the Northern Sea Route, mainly with use of remote sensing data from Synthetic Aperture Radar (SAR). Multivariate data analysis is the main tool used in this work. SAR signatures of different sea ice types and open water in winter were studied, and separation of water and sea ice types using different multivariate regression algorithms was done. Polynya areas along the coasts were investigated. Structure characteristics of different sea ice types and open water were investigated. The summer sea ice in the Laptev Sea was also studied. The Laptev Sea as well as other parts of the Northern Sea Route are expected to become important areas for future oil and gas exploration and exploitation.</p><p>Results from a statistical analysis of 105 SAR images and corresponding meteorological data are presented, covering parts of the Pechora and Kara Sea in the Russian Arctic. Wind, temperature and other variables for the SAR sample areas were collected, and a manual sea ice classification of the SAR samples was performed. All variables were input to different multivariate regression techniques. First, ice was separated from water. Next, young ice was separated from rough first year ice. The study indicated that the mean and standard deviation of the backscattering coefficients together with temperature values were the most important information to separate the classes. </p><p>SAR image data has been used to investigate specific polynya events in detail, addressing widths, refreezing and duration. A polynya index derived from ice concentration data from Special Sensor Microwave Imager (SSM/I) was used in the description of polynya variability during a decade (1990-1999) in response to atmospheric forcing. The observed polynya widths were compared to the results from a simple one-dimensional polynya model. The best agreement was found for the Vize and Ushakova Island and the Novaya Zemlya coast due to low variability of polynya widths. Less agreement was found at the Yamal and Taymyr due to high polynya variability not captured by the model.</p><p>Sample areas of open water, young ice and first year ice were investigated by the angle measure technique (AMT) and classified by multivariate regression. The separation of ice and water was relatively sucessfull, opposed to the separation of young ice and first year ice. The individual samples were best separated on one pixel scale, corresponding to backscattering differences between neighboring pixels. The AMT produce mean angle information that to some extent can be related to ice type.</p><p>Finally, a demonstration and validation study of the capabilities of SAR imagery to provide accurate ice information to support ice navigation was carried out. The experiment was set up in August-September 1997. RADARSAT and ERS-2 SAR images combined with SSM/I data and in situ observations from icebreakers were used. These data were used to analyze ice concentration, ice types, ice drift and other ice features present in this period. The capability of RADARSAT ScanSAR and ERS SAR images to determine these ice parameters during late summer conditions in the Laptev Sea area is discussed.</p>

Marine stratocumulus clouds cover extensive areas of the subtropical oceans and greatly influence Earth?s radiation by strongly reflecting the incoming solar radiation. The most climatologically pronounced stratus regime is located in the South-East Pacific. Drizzle is one of the several physical processes that affects the lifecycle and evolution of marine stratus by depleting the cloud liquid water and by stabilizing the marine boundary layer through evaporative cooling. In this study we use ship-borne radar observations from two innovative research cloud radars ? a Millimeter Cloud Radar (MMCR) (lambda=8 mm) and Frequency Modulated Continuous Wave (FMCW) radar (lambda=3 mm) to study the fallout of drizzle in the sub-cloud layer. Radar inter-comparison is used to perform calibration and quality control of the FMCW radar. The FMCW observations suffer no saturation and provide profiles of radar Doppler moments from the ship level to the cloud base. A lognormal drizzle drop size distribution is assumed and the parameters (N0, r0 and sigma x) are retrieved using the observed radar reflectivity and mean Doppler velocity profiles. The retrieved parameters are used to extract bulk parameters of the drizzle size distribution such as liquid water content, total number of droplets and rainfall rates at various heights within the sub-cloud layer (typically from 50-500 m). It is demonstrated that a simple evaporation model can be used to constrain the inversion from radar observables to drizzle size distribution parameters. The model output showed that the drizzle DSD is truncated at lower end due to the rapid evaporation of smaller drops and the logarithmic width of drizzle DSD is lower than the typically prescribed value of 0.35.

Mesoscale convective vortices (MCVs), which typically form within the stratiform rain of some mesoscale convective systems (MCSs), may persist for days, often regenerating convection daily. Long-lived MCVs can produce as much precipitation as a landfalling hurricane and lead to catastrophic flooding. The number of studies using multi-Doppler radar observations for validation of the kinematics, or three-dimensional (3-D) wind structure, of MCV genesis is limited. For this study, the Oklahoma City (KTLX) and Tulsa, Oklahoma (KINX) Weather Surveillance Radar – 1988 Doppler (WSR-88D) were used to examine the genesis of a long-lived MCV from 0000 to 0300 UTC on 11 June 2003. Traditional dual-Doppler techniques were used to determine the 3-D wind field. To relate MCV genesis within the associated larger MCS, time series of convective and stratiform precipitation, divergence, vertical vorticity, and vertical velocity were created for multiple levels within the MCS. The role of vertical vorticity generated in the convective region in MCV development was determined using vertical profiles of the terms in the vorticity tendency equation at 15 minute temporal resolution during the three hour period of investigation. The results of this study provide a detailed three hour examination for the initiation and early evolution of a long-lived MCV and can provide model validation of MCV generation.

<p>Detta självständiga arbete i militärteknik behandlar två simuleringsprogram för radarvågutbredning i syfte att undersöka konsekvenserna av dess nyttjande för den taktiske chefen till sjöss. Simuleringsprogrammens användbarhet mäts kvalitativt genom att respektive simuleringsprograms egenskaper ställs mot den taktiske chefens krav. Simulerings-programmen beskrivs utifrån teoretiska egenskaper i respektive program och utvärderas genom simuleringar av en typradar i tre olika vädertypfall. Den taktiske chefens krav grundas på personliga erfarenheter som fartygschef på korvett. Resultatet presenteras i form av positiva och negativa konsekvenser för den taktiske chefen vid nyttjande av respektive program.</p><p> </p> / <p>This is a bachelor thesis in Military Technology which deals with two radar wave propagation simulation programs. The purpose is to examine the consequences of their use for the tactical commander at sea. The simulation programs usability is estimated qualitative by the programs quality and attribute versus the tactical commander demands. The simulation programs are described from their theoretical quality and attribute respectively and evaluated by three simulations of the study’s specific radar in three different weather cases. The tactical commander demands are based on personal experiences as commanding officer of a corvette. The result is presented as positive and negative consequences for the tactical commander when using the simulation programs respectively.</p>

The main objective of this thesis is to contribute to the understanding of sea ice processes in the Northern Sea Route, mainly with use of remote sensing data from Synthetic Aperture Radar (SAR). Multivariate data analysis is the main tool used in this work. SAR signatures of different sea ice types and open water in winter were studied, and separation of water and sea ice types using different multivariate regression algorithms was done. Polynya areas along the coasts were investigated. Structure characteristics of different sea ice types and open water were investigated. The summer sea ice in the Laptev Sea was also studied. The Laptev Sea as well as other parts of the Northern Sea Route are expected to become important areas for future oil and gas exploration and exploitation. Results from a statistical analysis of 105 SAR images and corresponding meteorological data are presented, covering parts of the Pechora and Kara Sea in the Russian Arctic. Wind, temperature and other variables for the SAR sample areas were collected, and a manual sea ice classification of the SAR samples was performed. All variables were input to different multivariate regression techniques. First, ice was separated from water. Next, young ice was separated from rough first year ice. The study indicated that the mean and standard deviation of the backscattering coefficients together with temperature values were the most important information to separate the classes. SAR image data has been used to investigate specific polynya events in detail, addressing widths, refreezing and duration. A polynya index derived from ice concentration data from Special Sensor Microwave Imager (SSM/I) was used in the description of polynya variability during a decade (1990-1999) in response to atmospheric forcing. The observed polynya widths were compared to the results from a simple one-dimensional polynya model. The best agreement was found for the Vize and Ushakova Island and the Novaya Zemlya coast due to low variability of polynya widths. Less agreement was found at the Yamal and Taymyr due to high polynya variability not captured by the model. Sample areas of open water, young ice and first year ice were investigated by the angle measure technique (AMT) and classified by multivariate regression. The separation of ice and water was relatively sucessfull, opposed to the separation of young ice and first year ice. The individual samples were best separated on one pixel scale, corresponding to backscattering differences between neighboring pixels. The AMT produce mean angle information that to some extent can be related to ice type. Finally, a demonstration and validation study of the capabilities of SAR imagery to provide accurate ice information to support ice navigation was carried out. The experiment was set up in August-September 1997. RADARSAT and ERS-2 SAR images combined with SSM/I data and in situ observations from icebreakers were used. These data were used to analyze ice concentration, ice types, ice drift and other ice features present in this period. The capability of RADARSAT ScanSAR and ERS SAR images to determine these ice parameters during late summer conditions in the Laptev Sea area is discussed.

The Super Dual Auroral Radar Network (SuperDARN) of HF coherent radars has been originally designed to monitor echoes, and thus study physical processes, from within the auroral oval, the area with the most frequent occurrence of discrete auroras. Monitoring of higher latitudes, the so-called polar cap (including the magnetic Poles areas), was anticipated because of over-the-horizon nature of the radars, but this capability was considered to be a value-added feature. Recently (2006 and 2008), two new radars at Rankin Inlet and Inuvik (Canada) were installed by the University of Saskatchewan radar group to be able to monitor HF echoes from within the polar cap directly. In this Thesis, two aspects of the Rankin Inlet (RKN) radar observations are investigated. First, occurrence of ionospheric echoes is studied. Assessment of the echo occurrence rate is performed and the rate is compared with observations of concurrently operating Saskatoon and Halley (Southern hemisphere) SuperDARN radars. It is shown that the RKN overall occurrence rates (within the optimal area of detection) are ~20% which is well above the rates for the Saskatoon (~6%) and Halley (~1%) radars. The rates are somewhat smaller in the early morning (02-05 MLT) and postnoon (15-20 MLT) hours of magnetic local time. Seasonally, the rates are smaller for summer with significant drop near the magnetic noon. Secondly, an event of the RKN radar monitoring of a polar cap arc, progressing through the radar field of view, is presented. F region echoes are shown to be stronger in the arcs wake, and they are broader on both its sides. Arc-related sheared plasma flows were demonstrated by considering the radar velocity measurements. Occasional occurrence of strong shears away from the arc was noticed, and it was related to the onset of a second, sub-visual arc, emerging from the auroral oval and intruding the polar cap. The data presented demonstrate the usefulness of the RKN observations of the high-latitude arcs whose mechanism of formation is presently unclear. An attempt has been made to discern magnetic signatures of the polar cap arc. Magnetic perturbations were found to be very weak and not easily interpreted.

In this thesis, several aspects of HF coherent backscatter from the high-latitude E and F regions are studied with the focus on the relationship between the echo characteristics and the parameters of the ionosphere. The Hankasalmi CUTLASS/SuperDARN radar is the primary instrument for the undertaken studies. <p> The starting point in the research is that coherent echo characteristics are affected by two factors: the plasma physics of magnetic field-aligned irregularity formation and the propagation conditions in that the HF radio waves need to be close to the normal of the Earths magnetic field to detect the irregularities. Since the mechanisms of irregularity production are believed to be different at various heights, observations in the E and F regions are considered separately. <p>For the F-region backscatter, we first investigate the ionospheric conditions necessary for backscatter to be detected at specific latitudes and in specific time sectors. To achieve this goal, two approaches are employed. First, a long-term statistical study of diurnal, seasonal and solar cycle effects on echo occurrence is done to assess the relative importance of changes in plasma instability conditions and radio wave propagation. Next, echo occurrence is studied for an area in which ionospheric parameters are measured by EISCAT and other instruments. Both approaches indicate that F-region echoes occur if the electric field is enhanced (above 5-10 mV/m). We show that, once the electric field is above the threshold, the echo power is only slightly dependent on it. We demonstrate that the strongest echoes are received when the F-region electron density is optimal for the selected range and altitude. This optimal value is found to be about 2x1011 m-3 for the Hankasalmi radar. The role of the conducting E region on irregularity excitation and HF radio wave absorption are discussed. <p>The next problem considered with respect to the F-region echoes is the relationship between the velocity of the F-region echoes and plasma convection. We give additional evidence that the observed HF line-of-sight velocity is the projection of the convection velocity on the radar beam and that the Map Potential technique (currently in use for building the global-scale convection maps) compares well with the local EISCAT convection measurements. <p> With respect to the E-region backscatter, two major features are studied. First, a more detailed (as compared to the standard SuperDARN approach) analysis of the spectra is performed. By employing the Burg spectrum analysis method, we show that the E-region echoes are double-peaked in ~35% of observations. Variations of the peak separation with the range and azimuth of observations are investigated. The occurrence of double-peak echoes is associated with scatter from two different heights within the E region. HF ray tracing indicates that for typical ionospheric conditions, scatter from the top and the bottom of the E region is possible at certain slant ranges. In the upper layer the plasma waves move with the velocity close to the ExB convection component. For the lower layer, the plasma wave velocity is reduced due to enhanced ion and electron collision frequencies. A second issue is how do the velocities of HF and VHF E-region echoes compare for observations along the same direction. We concluded that the velocity of E-region echoes at HF can be comparable to or below the VHF velocity and well below the ExB convection component, implying that the scatter can often come from the bottom of the electrojet layer. Other aspects of VHF velocities are also discussed.

In this thesis, several aspects of HF coherent backscatter from the high-latitude E and F regions are studied with the focus on the relationship between the echo characteristics and the parameters of the ionosphere. The Hankasalmi CUTLASS/SuperDARN radar is the primary instrument for the undertaken studies. <p> The starting point in the research is that coherent echo characteristics are affected by two factors: the plasma physics of magnetic field-aligned irregularity formation and the propagation conditions in that the HF radio waves need to be close to the normal of the Earths magnetic field to detect the irregularities. Since the mechanisms of irregularity production are believed to be different at various heights, observations in the E and F regions are considered separately. <p>For the F-region backscatter, we first investigate the ionospheric conditions necessary for backscatter to be detected at specific latitudes and in specific time sectors. To achieve this goal, two approaches are employed. First, a long-term statistical study of diurnal, seasonal and solar cycle effects on echo occurrence is done to assess the relative importance of changes in plasma instability conditions and radio wave propagation. Next, echo occurrence is studied for an area in which ionospheric parameters are measured by EISCAT and other instruments. Both approaches indicate that F-region echoes occur if the electric field is enhanced (above 5-10 mV/m). We show that, once the electric field is above the threshold, the echo power is only slightly dependent on it. We demonstrate that the strongest echoes are received when the F-region electron density is optimal for the selected range and altitude. This optimal value is found to be about 2x1011 m-3 for the Hankasalmi radar. The role of the conducting E region on irregularity excitation and HF radio wave absorption are discussed. <p>The next problem considered with respect to the F-region echoes is the relationship between the velocity of the F-region echoes and plasma convection. We give additional evidence that the observed HF line-of-sight velocity is the projection of the convection velocity on the radar beam and that the Map Potential technique (currently in use for building the global-scale convection maps) compares well with the local EISCAT convection measurements. <p> With respect to the E-region backscatter, two major features are studied. First, a more detailed (as compared to the standard SuperDARN approach) analysis of the spectra is performed. By employing the Burg spectrum analysis method, we show that the E-region echoes are double-peaked in ~35% of observations. Variations of the peak separation with the range and azimuth of observations are investigated. The occurrence of double-peak echoes is associated with scatter from two different heights within the E region. HF ray tracing indicates that for typical ionospheric conditions, scatter from the top and the bottom of the E region is possible at certain slant ranges. In the upper layer the plasma waves move with the velocity close to the ExB convection component. For the lower layer, the plasma wave velocity is reduced due to enhanced ion and electron collision frequencies. A second issue is how do the velocities of HF and VHF E-region echoes compare for observations along the same direction. We concluded that the velocity of E-region echoes at HF can be comparable to or below the VHF velocity and well below the ExB convection component, implying that the scatter can often come from the bottom of the electrojet layer. Other aspects of VHF velocities are also discussed.