Advances in the development of simple and cheap sensors give new possibilities with large sensor network deployments in monitoring and surveillance applications. Commonly, the sensor positions are not known, specifically, when sensors are randomly spread in a big area. Low cost sensors are constructed with as few components as possible to keep price and energy consumption down. This implies that self-positioning and communication capabilities are low. So the question: “How do you localize such sensors with good precision with a feasible approach?” is central. When no information is available a stable and robust localization algorithm is needed. In this thesis an acoustic sensor network is considered. With a movable acoustic source a well-defined and audible signal is transmitted at different spots. The sensors measure the time of arrival which corresponds to distance. A two-step sensor localization approach is applied that utilizes the estimated distances. A novel approach in the first step is presented to incorporate more measurements and gain more position information. Localization and ranging performance is evaluated with simulations and data collected at field trials. The results show that the novel approach attains higher accuracy and robustness.

Pimple mounds are circular to elliptical domes with basal diameters ranging from 3 to more than 30 m, and heights of 30 cm to more than 2 m above intermound levels. For almost two centuries, the origin of these features has been speculated upon by scientists without general consensus as to one of over 30 different mechanisms suggested for their origin. These soil microfeatures can be observed throughout portions of East Texas as well as Louisiana, Arkansas, Oklahoma, and Missouri. Pimple mounds have been extensively mapped throughout East Texas as complexes covering over 1.0 million ha in 47 soil survey areas. About 600,000 ha are on Pleistocene-age geological formations. This study focused on 5,500 ha in Leon County, Texas, mapped as Rader-Derly complex and Derly-Rader complex. Rader (Aquic Paleustalfs) is on mounds and Derly (Typic Glossaqualfs) in the low intermounds. These soils are mapped primarily on terraces of the Trinity River system within the survey area. Using elevation levels published for the various fluviatile terrace deposits of the Trinity River, six groups (five terrace level groups and an upland group) were identified for analysis of mounds within the study area. Processes and factors of soil formation during the life of these features were considered using two methods ? remotely sensed elevation data and sampling data collected in the field. Size, shape, and relief of mounds were analyzed using airborne-based, remotely sensed LiDAR (Light Detection and Ranging) elevation data. Particle size distributions and pedon descriptions of mounds formed on materials of various ages were compared across the study area with special emphasis given to spatial trends. Analyses indicate a fluvial origin with pimple mound orientation corresponding to surrounding ridge and swale features of the paleoriver. Pimple mounds within the study area formed in the presence of sandy to loamy alluvial sediments and require the presence of accretionary ridge microtopography over point bar deposits. This alluvial parent material and topography were further developed by fluctuations in climate and vegetation over time. The erosional influence of bioturbation by animals and the intense rainfall and flood events which frequent the study area provided an environment in which these soil microfeatures have developed and over time exhibit increased levels of pedogenesis.

There is an increasing need for three-dimensional description for various applications such as the development of catchment areas, forest fire control and restoration. Three-dimensional information plays an indispensable role; therefore acquisition of the digital elevation models (DEMs) is the first step in these applications. LiDAR is a recent development in remote sensing with great potential for providing high resolution and accurate three-dimensional point clouds for describing terrain surface. The acquired LiDAR data represents the surface where the laser pulse is reflected from the height of the terrain and object above ground. These objects should be removed to derive the DEMs. Many LiDAR data-filtering studies are based on surface, block, and slope algorithms. These methods have been developed to filter out most features above the terrain; however, in certain situations they have proved unsatisfactory. The different algorithm based on different point of view to describe the terrain surface. The appropriate adoption of the advantages from these algorithms will develop a more complete way to derive DEMs. Knowledge-based system is developed to solve some specific problems according to the given appropriate domain knowledge. Huang (2007) proposed a Knowledge-based classification system in urban feature classification using LiDAR data and high resolution aerial imagery with 93% classification accuracy. This research proposed a knowledge-based LiDAR filtering (KBLF) as a follow-up study of Huang¡¦s study. KBLF integrates various knowledge rules derived from experts in the area of ground feature extraction using LiDAR data to increase the capability of describing terrain and ground feature classification. The filtering capability of KBLF is enhanced as expected to get better quality of referenced ground points to recover terrain height and DEMs using Inverse Distance Weighting (IDW) and Nearest Neighbor (NN) methods.

Light Detection and Ranging (Lidar) is a remote sensing technique that provides high resolution range measurements between the laser scanner and Earth’s topography. These range measurements are mapped as 3D point cloud with high accuracy (< 0.1 meters). Depending on the geometry of the illuminated surfaces on earth one or more backscattered echoes are recorded for every pulse emitted by the laser scanner. Lidar has the advantage of being able to create elevation surfaces in 3D, while also having information about the intensity of the returned pulse at each point, thus it can be treated as a spatial and as a spectral data system. The 3D elevation attributes of Lidar data are used in this study to identify possible water surface points quickly and efficiently. The approach incorporates the use of Laplacian curvature computed via wavelets where the wavelets are the first and second order derivatives of a Gaussian kernel. In computer science, a kd-tree is a space-partitioning data structure used for organizing points in a k dimensional space. The 3D point cloud is segmented by using a kd-tree and following this segmentation the neighborhood of each point is identified and Laplacian curvature is computed at each point record. A combination of positive curvature values and elevation measures is used to determine the threshold for identifying possible water surface points in the point cloud. The efficiency and accurate localization of the extracted water surface points are demonstrated by using the Lidar data for Williamson County in Texas. Six different test sites are identified and the results are compared against high resolution imagery. The resulting point features mapped accurately on streams and other water surfaces in the test sites. The combination of curvature and elevation filtering allowed the procedure to omit roads and bridges in the test sites and only identify points that belonged to streams, small ponds and floodplains. This procedure shows the capability of Lidar data for water surface mapping thus providing valuable datasets for a number of applications in geomorphology, hydrology and hydraulics. / text

The research problem that this thesis seeks to examine is a method of predicting conventional fire hazards using data drawn from specific regions, namely the Sooke and Goldstream watershed regions in coastal British Columbia. This thesis investigates whether LiDAR data can be used to describe conventional forest stand fire hazard classes. Three objectives guided this thesis: to discuss the variables associated with fire hazard, specifically the distribution and makeup of fuel; to examine the relationship between derived LiDAR biometrics and forest attributes related to hazard assessment factors defined by the Capitol Regional District (CRD); and to assess the viability of the LiDAR biometric decision tree in the CRD based on current frameworks for use. The research method uses quantitative datasets to assess the optimal generalization of these types of fire hazard data through discriminant analysis. Findings illustrate significant LiDAR-derived data limitations, and reflect the literature in that flawed field application of data modelling techniques has led to a disconnect between the ways in which fire hazard models have been intended to be used by scholars and the ways in which they are used by those tasked with prevention of forest fires. It can be concluded that a significant tradeoff exists between computational requirements for wildfire simulation models and the algorithms commonly used by field teams to apply these models with remote sensing data, and that CRD forest management practices would need to change to incorporate a decision tree model in order to decrease risk. / Graduate / 0799 / 0478 / christos@koulas.ca

This study aims to present and evaluate a new method for measuring the distribution of snow within built-up environments by differencing elevations collected by an Airborne Laser Scanner (ALS) before, and during peak snow accumulation. Few efforts have been made to study the distribution of snow within built-up environments due to the false assumption that high-intensity rainfall is the main contributor to peak yearly runoff rates. Traditional techniques for measuring snow are often difficult to replicate in built-up environments due to incompatibility of methods and barriers such as buildings, roads and private property. Light Detection and Ranging (LiDAR) technology, specifically ALSs, have previously been used to characterize the distribution of snow under forest canopy, and in remote mountain environments. This study investigates and assesses the utility of high resolution, non-intrusive ALS data for estimating the depth and distribution of snow within the town of Uxbridge, Ontario. ALS flights for this study were completed before the onset of snow accumulation, as well as near peak snow accumulation for the winters of 2010 and 2011. Pre and post snow accumulation ALS measured elevations were differenced to estimate the depth of the snowpack across the entire study area at a resolution of 0.5 m. Ground measurements of snow depth were also completed within 24 hours of each of the winter flights. The LiDAR-estimated and ground-measured snow depths were compared using Spearman's rank correlation coefficient as well as Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE). Results from this thesis show that: 1) Snow depths estimated by differencing elevations from two ALS flights show a MAE of 3 cm and an RMSE of 10 cm when compared to ground-measured snow depths. (2) There is a strong, statistically significant relationship (ρ = 0:82, p < 0:001) between LiDAR-estimated and ground-measured snow depths. (3) An average bias of -3 cm was found for the entire dataset showing an underestimation in the LiDAR-estimated snow depths most likely caused by the effects of low lying vegetation on the fall ALS measurements. The results presented in this study demonstrate that ALSs are capable of providing high spatial resolution snow depth estimates within built-up environments. Furthermore, snow depth measurements made using an ALS can be used to increase the current body of knowledge on the distribution and re-distribution of snow within built-up environments. Snow distributions measured by an ALS could also be used for future development and verification of urban hydrological models.

Title from second page of PDF document. Includes bibliographical references (p. 145-173).

Various ecological and human-induced disturbances play an important role in defining the health of an animal. To cope up with such threats or challenges to its homeostasis, an animal responds by secreting stress hormones (glucocorticoids) to mobilize the energy. In general, glucocorticoids help animals to cope up with the ‘stressors’. Prolonged exposure to any ‘stressors’ may lead to an elevation in the levels of glucocorticoids, thereby leading to reproductive inhibition, immune system suppression, neuronal death and impaired cognitive function and hence, threatening the survival and fitness of an animal. However, the long-term effects of environmental or anthropogenic disturbances on the fitness and survival are difficult to analyze in a slow reproducing, long-lived species such as elephants. Spread over 3% of India’s geographical area, India shelters around 28,000 to 30,000 Asian elephants (Elephas maximus; Bist, 2002; Santiapillai and Sukumar, 2006). Protected areas in India are estimated to form 22% of elephant habitat; while the rest of the elephant habitats extend outside the protected areas (Lenin and Sukumar, 2011) making them vulnerable to human-induced threats. Consequently, there are increased incidences of human-elephant conflicts leading to crop and property depredation and human-elephant mortality. Most of the studies, in context of such conflicts, highlight the temporal, spatial scales of conflicts majorly focusing on mitigation measures. None of the studies so far have elucidated how escalating human-elephant conflicts would influence the physiological health of Asian elephants. This study, hence, focused on addressing the proximate causation of the stress-response in free-ranging Asian elephants of the Bandipur National Park, the Nagarahole National Park and Hassan district of Karnataka, using a non-invasive technique for measuring faecal glucocorticoid metabolites (fGCM). There are several factors which could act as possible stressors to the physiological state of an elephant, but depending upon the feasibility and time limitations of conducting the study, we selected those factors which we thought are essential to address the proximate causation of stress-response in Asian elephants. Being the first detailed study to explore the stress-response in free-ranging Asian elephants, this study attempted to understand the influence of some of the fundamental ecological (seasonality, group size, and body condition) and human-induced stressors. The main body of the dissertation is divided into six chapters. The first and the last chapters discuss the general introduction and conclusion while the rest four chapters highlight the main four objectives of the study. The main objectives of the thesis were: 1. The first objective of this thesis was to validate and standardize some of the crucial parts of protocols to avoid any technique-based bias while interpreting the levels of faecal glucocorticoid metabolites. Under the first objective, the influences of some of the fundamental intrinsic and extrinsic factors on the fGCM levels were also assessed. 2. The second objective was to assess the association between body condition, seasonality and stress response. 3. Having assessed the relationship between body condition and stress-status, the third objective focused on the influence of socio-ecological correlates such as group size, lactational status and the presence of adult females in a herd on the stress status of female adult elephants. 4. With above three objectives majorly highlighting the influence of ecological factors, the fourth objective was to assess the influence of anthropogenic factors on stress-response of free-ranging elephants under which we compared the stress-response between crop-raiding in human-dominated and nonraiding elephants in forested habitats. The study was conducted during dry season (February to May) and wet season (August to December) of 2013 and 2015. The dissertation is organized in the following way: Chapter 1: General Introduction The first chapter provides a general introduction about stress response and its physiological pathway. It also discusses the importance of non-invasive technique used in our study. It highlights the significance of this study based on the available literature on both African and Asian elephants. Chapter 2: General validation and standardization of field techniques and assays; influence of intrinsic and extrinsic factors on faecal glucocorticoid metabolites This chapter is divided into two parts. The first part deals with general validation and standardization of field techniques and the second part assesses the influence of fundamental intrinsic and extrinsic factors. Being the first study on stress-response of free-ranging Asian elephants, influence of various field-based techniques and variations were studied to facilitate the reliable interpretation of fGCM levels. We first conducted the experiments to standardize the field protocol and the laboratory protocol. Under the field protocol, we found that there was no within sample variation (as observed in many other species) in fGCM levels from thoroughly mixed faecal samples and samples from the center of the same dung bolus. The time of collection of samples had a significant influence, suggesting that the concentration of fGCM remains stable until 6-9 hours. Influence of storage of lyophilized samples suggested that the concentrations of fGCM levels decline if exposed to moisture. Under the laboratory protocol, A group specific 11-oxoetiocholanolone EIA, used for analyzing fGCM levels (μg/g), was modified to enhance the repeatability, accuracy and precision. EIA was analytically validated in every hormonal analysis by calculating the inter- and intra-assay coefficients of variation, specificity and parallelism. In the second part, we assessed the influence of age, sex and season on fGCM levels and found there was no age-wise variation and sex-wise variation. Season-wise variation was significant only in female elephants. We discuss the potential physiological reasons behind such variation. These findings suggest that aspects such as time of collection, proper storage of samples and the influence of extrinsic stresses (seasonality) should be considered for reliable and unbiased interpretation of fGCM levels. Chapter 3: Assessment of season-dependent body condition scores in relation to faecal glucocorticoid metabolites in free-ranging Asian elephants. (Published in Conservation Physiology; Pokharel et al., 2017; doi:10.1093/conphys/cox039) We studied seasonal and annual changes in visual body condition scores (BCS), and assessed how these scores were related to levels of fGCM levels in free-ranging Asian elephants in the seasonally dry tropical forests of the Mysore and Nilgiri Elephant Reserves in southern India. We assessed the animals’ BCS visually on a scale of 1 to 5; where 1 represents a very thin and 5 represents a very fat elephant. To understand the influence of seasonality on BCS, we sampled the population during dry and wet seasons of 2013 and 2015 while, for annual changes in BCS, we sampled nine free-ranging adult females from different family groups that had been repeatedly sighted over seven years. To evaluate the influence of body condition on fGCM, we measured the fGCM levels from fresh fecal samples collected from the body-condition scored animals. Effect of age and season on BCS in relation to fGCM was also studied. We found that the BCS was related with season, i.e. individuals with low BCS were more frequent during the dry season as compared to the wet season and fGCM levels were negatively associated with BCS. To be precise, concentrations of fGCM were highest in individuals with the lowest BCS (BCS-1) and then significantly declined till BCS-3. fGCM levels were almost comparable for BCS 3, 4 and 5. This pattern was more conspicuous in female than in male elephants. We discussed the possible reasons behind such relationship between fGCM and BCS. The findings from this chapter suggest that season-dependent BCS, hence, reflect the stress status as measured by fGCM, especially in female Asian elephants and could be used as an important non-invasive approach to monitor the physiological health of free-ranging elephant populations. This is the first study to compare the body condition scores and stress-response in free-ranging elephants. Chapter 4: Influence of ecological and physiological correlates on stress physiology of free-ranging female Asian elephants. We investigated the influence of herd size (HS), lactational status and number of adult females present in a herd on adrenocortical function in free-ranging adult female Asian elephants by measuring their fecal glucocorticoid metabolites (fGCM) levels. We found that there was a negative association between herd size and fGCM levels when only HS and fGCM were compared. Lactating females showed higher fGCM than that observed in non-lactating females, which might reflect the nutritional stress on mother and anti-predatory challenges against the calves. Herds with only one adult female had higher fGCM levels than herds with more than one adult female which could be because of social challenges. The poor association between herd size and fGCM when all predictor variables were combined elucidate that group size may not necessarily influence the adreno-cortical function. However, the numbers of adult females present in a herd and their lactational status has a significant role in defining the stress-response in free-ranging adult female Asian elephants. This study is the first study to document the influence of lactational status with the stress-response in free-ranging elephants. Chapter 5: How physiologically costlier it is to be a crop-raider in a human-dominated landscape? Diet quality as a possible ‘pacifier’ against stress. We studied the stress-response in crop-raiding elephants in a human-dominated landscape and non-raiding elephants in the protected forested areas. While raiding agricultural crops, elephants face various associated threats such as retaliation by humans, human-induced disturbances and stress of raiding which could enhance the energetic costs, ultimately elevating their stress levels. We hypothesized that crop-raiders (in human-dominated landscape; Hassan district of Karnataka, India) will exhibit higher faecal glucocorticoid metabolite (a proxy of stress-response; fGCM) levels as compared to the nonraiders (in forested areas; Bandipur and Nagarahole National Parks). Contrary to our hypothesis, fGCM levels were found to be higher in both nonraiding female and male elephants than female and male crop-raiders. To assess the influence of benefits obtained from crop-raiding as one of the possible factors for the lower fGCM in crop-raiders, the difference in vegetation between human-dominated landscape and forested areas were further analyzed by using a remotely sensed NDVI (Normalized Differential Vegetation Index) and was ground-truthed by measuring the quality of diet (C:N ratio through fecal samples). Interestingly, the NDVI values were higher at the human-dominated and the C:N ratio was lower (higher Nitrogen content) in faecal samples of crop-raiding elephants (both in females and in males) than the nonraiders in the forested areas. Positive correlation was observed between C:N ratio and fGCM levels. These findings suggest that crop-raiding comes with the benefits of easy access to good quality of diet which may help in reducing the stress-response in elephants while being in the human-dominated landscapes, provided there is a low intensity of human disturbance. This is the first study to document and compare the stress-status of crop-raiding Asian elephants with elephants in their natural habitats using NDVI and C:N ratio. Chapter 6: Conclusion In conclusion, the work presented in this dissertation provides an overview of how ecological and anthropogenic factors could influence the physiological health of free-ranging Asian elephants. This dissertation focused on providing detailed insights about the stress-response in free-ranging Asian elephants. The objectives have been achieved by assessing the relationship between ecological stressors such as seasonality, body condition, herd size, lactational status, a presence of individuals in a herd and anthropogenic stressors such as human-induced threats or crop-raiding using well-validated and standardized laboratory and field protocols. This study provides valuable insights into the physiological health or stress-response being synergistically influenced by various ecological, social and anthropogenic factors in free-ranging Asian elephants. Findings obtained from this study could help in addressing the issues related to the management of free-ranging elephant populations.

Submitted by Fernanda Rodrigues de Lima (fernanda.rlima@ufpe.br) on 2018-09-26T21:08:19Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Rafael Lopes Mendonça.pdf: 5746497 bytes, checksum: 6427f5355ad301a77ff31c0401d54da5 (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-10-01T15:23:00Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Rafael Lopes Mendonça.pdf: 5746497 bytes, checksum: 6427f5355ad301a77ff31c0401d54da5 (MD5) / Made available in DSpace on 2018-10-01T15:23:00Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Rafael Lopes Mendonça.pdf: 5746497 bytes, checksum: 6427f5355ad301a77ff31c0401d54da5 (MD5) Previous issue date: 2017-08-31 / CNPq / Com o crescente uso do escaneamento a LASER aerotransportado para aquisição de Modelo Digital, tem-se observado um maior interesse em desenvolver técnicas de filtragens capazes de gerar um Modelo Digital do Terreno (MDT) de forma automática. Os métodos existentes na literatura consideram regiões mais uniformes, com características diferentes das encontradas nas cidades brasileiras, principalmente em áreas onde há uma maior variação do relevo e diversidade de elementos, tanto naturais quanto artificiais, sobre o solo exposto. Diante disto, o presente trabalho tem como objetivo analisar algumas técnicas existentes, e propor uma abordagem para a filtragem de dados Light Detection And Ranging (LIDAR) para geração de MDT. A área de estudo corresponde a uma região do bairro do Vasco da Gama, na cidade de Recife, capital Pernambucana. Esta região apresenta um relevo acidentado com grande concentração de imóveis, além da presença de vegetação arbórea e rasteira. Através de alguns métodos de filtragens foram analisados os resultados obtidos para essa área de estudo. A combinação dos métodos de identificação de bordas e da classificação supervisionada apresentou resultado mais satisfatório, em comparação aos outros utilizados nesta dissertação. / With the increasing use of the airborne LASER scanning to acquire Digital Model, it has been observed a greater interest in developing filtering techniques capable of generating a Digital Terrain Model (DTM) automatically. The existing methods in the literature consider more uniform regions, with characteristics different from those found in Brazilian cities, especially in areas where there is a greater variation of the relief and diversity of elements, both natural and artificial, above the ground. Therefore, the present work aims to analyze some existing techniques, and to propose an approach to Light Detection and Ranging (LIDAR) data filtering for MDT generation. The study area corresponds to a region of the neighborhood of Vasco da Gama, in the city of Recife, capital of Pernambuco. This region presents a rough relief with great urban agglomeration, besides the presence of arboreal and low vegetation. Through some filtration methods the results obtained for this area of study were analyzed. The combination of the methods of edge identification and supervised classification presented a more satisfactory result, compared to the others used in this dissertation.

One of the applications of the Satellite Laser Ranging (SLR) technique is the derivation of gravity field models; these models have various geophysical and geodynamical applications. Gravity field modelling has reached a new era where the latest satellite missions (CHAMP, GRACE and GOCE) are thought to provide significant improvement of global gravity field information in terms of quality and spatial resolution. In particular, the recent satellite missions carry on-board Global Navigation Satellite System (GNSS) receivers, accelerometers, K/Kaband microwave system (e.g. in GRACE) and gradiometers (e.g. in GOCE) allowing measurements of gravity field with unprecedented accuracy in contrast to the unsteady and fragmented orbit tracking by unevenly distributed SLR ground stations. Numerous gravity field models have been derived based on the newly available data sets by various research groups globally. Due to the availability of high quality SLR and satellite data, some of the older gravity field models are being updated as new models with higher degree and order are developed. Notwithstanding the significant progress in gravity field modelling, research focusing on assessing the accuracy and precision of the existing gravity field models has largely remained insufficient. The difference between the observed and computed satellite orbit (which is often expressed as the O-C range residuals) is used as a parameter for Precise Orbit Determination (POD) of satellites. Furthermore, O-C range residuals computed during SLR analysis are used as proxy parameters for evaluating the accuracy of gravity field models. The work presented in this thesis firstly reviewed and evaluated the accuracy of gravity field models released between 1990 and 2008. The accuracy of the gravity field models was examined by analysing the O-C residuals computed from LAGEOS 1 and 2 data analysis based on a set of twelve gravity field models. The results demonstrated that in general, there has been an improvement in the accuracy of gravity field models released between 1990 and 2008 by a factor of 2 based on improvements in the O-C residuals. Additionally, the influence of SLR tide parameterization (the IERS 2010 solid Earth and pole tide models) on the O-C residuals across five gravity field models has been assessed and results illustrate that the solid Earth and pole tides parameterization influence on the O-C residuals is dependent on the type of gravity field model. In order to ascertain the significance of mean differences in the Standard Deviations (SD) of O-C residuals based on the tide parameterization options, the student’s t-test was used. Results suggest that in general the O-C residuals derived from SLR LAGEOS 1 data have insignificant mean SD differences across the tide parameterizations. On the other hand analysis of SLR observations of LAGEOS 2 resulted in statistically significant mean SD differences in the O-C based on EIGEN-CG03C, EGM2008 and AIUB-GRACE01S gravity field models. The J2 coefficient forms part of the SLR Data Analysis Software (SDAS) package output products and was investigated in this thesis due to its role in understanding mass-redistribution within the Earth system (i.e. the equatorial bulge due to centrifugal force and rotation). In particular, the J 2 coefficient computed from SLR analysis of LAGEOS 1 and 2 data sets and based on the four selected gravity field models were compared with a priori J2 coefficients from the four models and those published in the literature. The results indicated that the J2 coefficients computed from the SDAS package were in agreement with the published coefficients. For geophysical applications, the relationship between the J2 parameter and LOD and AAM was investigated by use of data adaptive analysis methodology (the empirical mode decomposition). The results demonstrated that some degree of synchronization exists between the signal components of J2 and LOD and J2 and AAM. / Thesis (PhD)--University of Pretoria, 2013. / Geography, Geoinformatics and Meteorology / Unrestricted