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Journal articles on the topic "Geoid model"
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Balodis, Janis, Katerina Morozova, Gunars Silabriedis, Maris Kalinka, Kriss Balodis, Ingus Mitrofanovs, Irina Baltmane, and Izolde Jumare. "CHANGING THE NATIONAL HEIGHT SYSTEM AND GEOID MODEL IN LATVIA." Geodesy and cartography 42, no. 1 (April 8, 2016): 20–24. http://dx.doi.org/10.3846/20296991.2016.1168009.
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According to the decision of IAG Reference Frame Sub-commission for Europe (EUREF) the EVRF2007 solution as the vertical reference has to be deployed in EU countries.The new height system LAS-2000,5 had been enacted as the European Vertical Reference System‘s EVRF2007 realization in Latvia and the new geoid model LV‘14 had been introduced by Latvian authority Latvian Geospatial Information Agency. However, the appreciation of the quality of quasi-geoid model LV‘14 is rather contradictious among the users in Latvia. The independent estimate and comparison of the two Latvian geoid models developed till now has been performed by the Institute of Geodesy and Geoinformatics. Previous geoid model LV98 which was developed for Baltic-1977 height system almost 20 years ago is outdated now. Preparatory actions described in order to fulfil the task of comparison the geoids in two different height systems. The equations and transformation parameters are presented in this article for the normal height conversion from Baltic-1977 height system to the Latvian realization named LAS-2000,5. The comparison is performed of both Latvian quasigeoid models – the new one LV‘14 and previous LV98. The quality of both models estimated by controlling the geoid heights at the properly densified GNSS/levelling network sites. The distribution of discrepancies in comparison with normal distribution N(x,μ,s) is depicted in corresponding figures. For LV‘14 quasi-geoid model the standard deviation of discrepancies is 3.2 cm, 75% of discrepancies x ≤ 3.2 cm. For LV98 quasigeoid model the standard deviation of discrepancies is 4.7 cm, 80% of discrepancies x ≤ 6 cm. Without doubt, the newly developed LV‘14 quasi-geoid model is of higher quality.
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Buczyńska, Anna. "Precision study of satellite levelling with using various models of geoid." E3S Web of Conferences 71 (2018): 00015. http://dx.doi.org/10.1051/e3sconf/20187100015.
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The main purpose of this study is comparison of orthometric heights of measuring points and the accuracy of these heights depending on selected geoid model and measurement method. In addition, for better understanding of the essence of conducted research, paper provides information about: geoid and other surfaces used in geodesy to describe the terrestrial globe, modelling methods of equipotential surfaces and data that can be used to develop them, the most important geoid models developed for the area of Poland and the world, the technique of determining the orthometric heights using various measuring methods. Heights of two measuring points, located on the premises of Wrocław University of Science and Technology, were determined to achieve thesis statement. The scope of the study is limited to determining the orthometric heights of points for three global geoid models and four geoid models developed for the area of Poland. Among the selected equipotential surfaces were: geoida niwelacyjna 2000, GUGiK 2001, GEOIDPOL 2008A/C/CN, PL-GEOID-2011, OSU91, EGM96 and EGM2008.
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Pahlevi, Arisauna M., Ibnu Sofian, Dyah Pangastuti, and Antonius B. Wijanarto. "UPDATING MODEL GEOID INDONESIA." Seminar Nasional Geomatika 3 (February 15, 2019): 761. http://dx.doi.org/10.24895/sng.2018.3-0.1063.
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Geoid merupakan referensi tinggi di Indonesia sesuai amanat Peraturan Kepala BIG (Perka BIG) nomor 15 Tahun 2013 tentang Sistem Referensi Geospasial Indonesia (SRGI). Melalui website http://srgi.big.go.id/srgi2, BIG secara bertahap memenuhi kebutuhan masyarakat terkait dengan sistem referensi geospasial termasuk di dalamnya informasi model geoid Indonesia. Model geoid Indonesia yang dihasilkan pada tahun 2013 merupakan model geoid Indonesia yang diolah berbasis pulau. pada tahun 2018, dilakukan updating model geoid Indonesia. Tujuannya untuk menghasilkan model geoid Indonesia secara keseluruhan atau terintegrasi di seluruh wilayah Indonesia. Data yang digunakan adalah; Data spherical harmonic beberapa model geoid global sebagai data gelombang panjang, data gelombang menengah menggunakan Data DTU-10, data gayaberat airborne wilayah Pulau Sulawesi, Kalimantan dan Papua. Sedangkan data gelombang pendek menggunakan Data SRTM-15 meter. Metode yang digunakan dalam pemodelan geoid adalah metode Fast Fourier Transform (FFT). Data-data tersebut diolah dengan menggunakan perangkat lunak gravsoft yang telah dimodifikasi di sesuaikan dengan kebutuhan Indonesia. Validasi model geoid dilakukan dengan membandingkan nilai geoid gravimetrik hasil pengolahan model geoid dari data gayaberat, dengan nilai geoid geometrik dari pengukuran GNSS di pilar Tanda Tinggi Geodesi (TTG). Dari pengolahan data, menghasilkan model geoid dari beberapa data komponen gelombang panjang yang berbeda. Model geoid dengan standar deviasi terkecil adalah model geoid yang diperoleh dari kombinasi komponen gelombang panjang EGM2008 - derajat 2190 dengan nilai standar deviasi 0.2283. Metode pemodelan geoid secara menyeluruh di seluruh wilayah Indonesia lebih relevan dilakukan di negara kepulauan seperti Indonesia, dikarenakan lebih memudahkan unifikasi model geoid antara darat dan laut.
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IBRAHIM YAHAYA, Salissou, El Hassan EL BRIRCHI, and Driss EL AZZAB. "IMPACT OF DATUM TRANSFORMATION ON LOCAL VARIATIONS OF GEOMETRIC GEOID IN NIGER." Geodesy and cartography 43, no. 4 (December 21, 2017): 147–57. http://dx.doi.org/10.3846/20296991.2017.1412615.
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In this study, we have conducted an investigation on the impact of the coordinates’ transformation on local variations of geometric geoid. The study area is limited by 1°43′12″ to 4°00′37″ East and 13°01′57″ to 14°31′20″ North in the southwest of the Niger Republic. We used 39 network GPS/levelling points established by the Japan International Cooperation Agency (JICA) and the National Geographic Institute of Niger (IGNN), including the DOPPLER point ANG302/no.65. Using other coordinates of point no. 65 provided by IGNN, we transformed the points into WGS84 and computed a new geometric geoid model. The comparison of the new model with EGM2008 geoid up to d/o 2160 gives the STD of 15 cm and the RMS of 16cm. Local variations of the geometric geoids, were compared to that of EGM2008 geoid. The comparison through basic statistics, trend lines and 3D overlaps, showed a similar trend between the geometric geoid from the transformed coordinates and that of EGM2008. On the contrary, the JICA-IGNN geometric geoid generated an opposite and exaggerated trend. The Jarque-Bera test confirms that the three samples follow a normal distribution at the significance level α = 5%. The equality of variances between EGM2008 and JICA-IGNN geoids has been rejected by the Fisher’s F-Test/two-tailed at α = 10%. However the test confirms the variances equality between EGM2008 and the transformed geometric geoid at α = 5% and α = 10%. The two-tailed Student’s T-Test at α = 5% also confirms the equality of means between EGM2008 geoid and transformed geometric geoid samples.
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Stammer, Detlef, Armin Köhl, and Carl Wunsch. "Impact of Accurate Geoid Fields on Estimates of the Ocean Circulation." Journal of Atmospheric and Oceanic Technology 24, no. 8 (August 1, 2007): 1464–78. http://dx.doi.org/10.1175/jtech2044.1.
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Abstract The impact of new geoid height models on estimates of the ocean circulation, now available from the Gravity Recovery and Climate Experiment (GRACE) spacecraft, is assessed, and the implications of far more accurate geoids, anticipated from the European Space Agency’s (ESA) Gravity and Ocean Circulation Explorer (GOCE) mission, are explored. The study is based on several circulation estimates obtained over the period 1992–2002 by combining most of the available ocean datasets with a global general circulation model on a 1° horizontal grid and by exchanging only the EGM96 geoid model with two different geoid models available from GRACE. As compared to the EGM96-based solution, the GRACE geoid leads to an estimate of the ocean circulation that is more consistent with the Levitus temperature and salinity climatology. While not a formal proof, this finding supports the inference of a substantially improved GRACE geoid skill. However, oceanographic implications of the GRACE model are only modest compared to what can be obtained from ocean observations alone. To understand the extent to which this is merely a consequence of a not-optimally converged solution or if a much more accurate geoid field could in principle play a profound role in the ocean estimation procedure, an additional experiment was performed in which the geoid error was artificially reduced relative to all other datasets. Adjustments occur then in all elements of the ocean circulation, including 10% changes in the meridional overturning circulation and the corresponding meridional heat transport in the Atlantic. For an optimal use of new geoid fields, improved error information is required. The error budget of existing time-mean dynamic topography estimates may now be dominated by residual errors in time-mean altimetric corrections. Both these and the model errors need to be better understood before improved geoid estimates can be fully exploited. As is commonly found, the Southern Ocean is of particular concern.
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Erol, Serdar, Emrah Özögel, Ramazan Alper Kuçak, and Bihter Erol. "Utilizing Airborne LiDAR and UAV Photogrammetry Techniques in Local Geoid Model Determination and Validation." ISPRS International Journal of Geo-Information 9, no. 9 (September 2, 2020): 528. http://dx.doi.org/10.3390/ijgi9090528.
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This investigation evaluates the performance of digital terrain models (DTMs) generated in different vertical datums by aerial LiDAR and unmanned aerial vehicle (UAV) photogrammetry techniques, for the determination and validation of local geoid models. Many engineering projects require the point heights referring to a physical surface, i.e., geoid, rather than an ellipsoid. When a high-accuracy local geoid model is available in the study area, the physical heights are practically obtained with the transformation of global navigation satellite system (GNSS) ellipsoidal heights of the points. Besides the commonly used geodetic methods, this study introduces a novel approach for the determination and validation of the local geoid surface models using photogrammetry. The numeric tests were carried out in the Bergama region, in the west of Turkey. Using direct georeferenced airborne LiDAR and indirect georeferenced UAV photogrammetry-derived point clouds, DTMs were generated in ellipsoidal and geoidal vertical datums, respectively. After this, the local geoid models were calculated as differences between the generated DTMs. Generated local geoid models in the grid and pointwise formats were tested and compared with the regional gravimetric geoid model (TG03) and a high-resolution global geoid model (EIGEN6C4), respectively. In conclusion, the applied approach provided sufficient performance for modeling and validating the geoid heights with centimeter-level accuracy.
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Pisetskaya, Olga, and Alexander Yarmolenko. "Problem of Determining a Geoid." Baltic Surveying 8 (October 31, 2018): 85–92. http://dx.doi.org/10.22616/j.balticsurveying.2018.011.
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The issue of the study of the problem of determining the geoid and quasi-geoid models is considered. Development of methods for constructing an exact geoid model using different dimensions. Analysis of the calculation of normal heights using satellite measurements, construction of geoid and quasi-geoid models by different methods is performed. Based on the results of the analytical review of existing methods for determining the geoid, it was proposed to use various data (geodetic heights, mixed gravity anomalies, anomalous potential) to construct this model, which allows building a model of a geoid with millimetre accuracy. The possibility of using the collocation method is considered. The task is to develop a methodology for constructing a geoid model using a network of low density gravity points and using pure and mixed gravity anomalies, which allows us to solve the problem of finding potential by solving the Laplace equation or using wavelets.
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Kim, Kwang Bae, Hong Sik Yun, and Ha Jung Choi. "Accuracy Evaluation of Geoid Heights in the National Control Points of South Korea Using High-Degree Geopotential Model." Applied Sciences 10, no. 4 (February 21, 2020): 1466. http://dx.doi.org/10.3390/app10041466.
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Precise geoid heights are not as important for understanding Earth’s gravity field, but they are important to geodesy itself, since the vertical datum is defined as geoid in a cm-level accuracy. Several high-degree geopotential models have been derived lately by using satellite tracking data such as those from Gravity Recovery and Climate Experiment (GRACE) and Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), satellite altimeter data, and terrestrial and airborne gravity data. The Korean national geoid (KNGeoid) models of the National Geographic Information Institute (NGII) were developed using the latest global geopotential models (GGMs), which are combinations of gravity data from satellites and land gravity data. In this study, geoid heights calculated from the latest high-degree GGMs were used to evaluate the accuracy of the three GGMs (European Improved Gravity model of Earth by New techniques (EIGEN)-6C4, Earth Gravitational Model 2008 (EGM2008), and GOCE-EGM2008 combined model (GECO)) by comparing them with the geoid heights derived from the Global Navigation Satellite System (GNSS)/leveling of the 1182 unified control points (UCPs) that have been installed by NGII in South Korea since 2008. In addition, the geoid heights derived from the KNGeoid models were compared with the geoid heights derived from the GNSS/leveling of the 1182 UCPs to assess the accuracy of the KNGeoid models in terms of relative geoid heights for further gravimetric geoid determination studies in South Korea. As a result, the EGM2008 model could be selected as the suitable GGM from among the three GGMs for determining a gravimetric geoid model for South Korea.
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Jürgenson, Harli, Kristina Türk, and Jüri Randjärv. "DETERMINATION AND EVALUATION OF THE ESTONIAN FITTED GEOID MODEL EST-GEOID 2003 / ESTIJOS GEOIDO MODELIO EST-GEOID 2003 SUDARYMAS IR VERTINIMAS / СОЗДАНИЕ И ОЦЕНКА МОДЕЛИ ГЕОИДА ЭСТОНИИ EST-GEOID2003." Geodesy and Cartography 37, no. 1 (April 15, 2011): 15–21. http://dx.doi.org/10.3846/13921541.2011.558339.
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This paper focuses on issues related to the calculation of a high-precision fitted geoid model on Estonian territory. Model Est-Geoid2003 have been used in Estonia several years in geodesy and other applications. New data from precise levelling, new global models and terrestrial gravity data give plenty of possibilities for updates and accuracy evaluation. The model is based on a gravimetric geoid. From the gravimetric data gathered, a gravimetric geoid for Estonia was calculated as an approximately 3-km net using the FFT method. After including the new gravimetric data gathered, the gravimetric geoid no longer had any significant tilt relative to the height anomalies derived from GPS-levelling points. The standard deviation between the points was 2.7 cm. The surface of the calculated gravimetric geoid was fitted by high-precision GPS-levelling points. As a result, a height transformation model was determined to reflect the differences between the normal heights of BK77 and the ellipsoidal heights of EUREF-EST97 on Estonian territory. The model was originally called Est-Geoid2003 and is part of the official national geodetic system in Estonia. The model is updated and evaluated here using precise GPS-levelling points obtained from different measurement campaigns. In 2008–2010 the preliminary results from the latest precise levelling sessions became available, leading to a significant increase in the number of precise GPS-levelling points. Both networks are part of the Estonian integrated geodetic network. Using very precise levelling connections from new levelling lines, normal heights of several RGP points were calculated additionally. Misclosure of 300 km polygons are less than 2–3 mm normally. Ealier all precisely levelled RGP points were included into fitting points. Now many new points are available for fitting and independent evaluation. However, the use of several benchmarks for the same RGP point sometimes results in a 1–2 cm difference in normal height. This reveals problems with the stability of older wall benchmarks, which are widely used in Estonia. Even we recognized, that 0.5 cm fitted geoid model is not achievable using wall benchmarks. New evaluation of the model Est-Geoid2003 is introduced in the light of preliminary data from new precise levelling. Model accuracy is recognised about 1.2 cm as rms. Santrauka Akcentuojami klausimai, susiję su tiksliausio Estijos geoido modelio skaičiavimu. Šis modelis Estijoje geodezijoje ir kitose mokslo bei technikos šakose taikomas nuo 2003 metų. Nauji precizinės niveliacijos duomenys, nauji globalieji geopotencialo modeliai ir žemyno gravimetriniai duomenys – prielaidos geoido modeliui atnaujinti ir jo tikslumui įvertinti. Modelio pagrindas – gravimetrinis geoidas. Pagal surinktus gravimetrinius duomenis Estijos geoidas buvo apskaičiuotas greitųjų Furjė tranformacijų (FFT) metodu, sukuriant apie 3 km akių tinklą. Įtraukus naujuosius gravimetrinius duomenis, gravimetrinis geoidas daugiau nebeturi aukščių anomalijų. Vidutinė kvadratinė paklaida – 2,7 cm. Apskaičiuoto gravimetrinio geoido paviršius susietas su aukščių sistema pagal GPS niveliacijos taškus. 2008–2010 m. gavus precizinės niveliacijos duomenis, žymiai padidėjo GPS niveliacijos taškų skaičius bei jų tikslumas, nes precizinės niveliacijos poligonų iki 300 km nesąryšiai gauti mažesni nei 2–3 mm. Įvertinus naujo Estijos geoido modelio tikslumą nustatyta 1,2 cm vidutinė kvadratinė paklaida. Резюме Акцентируются вопросы, касающиеся вычисления точной модели геоида Эстонии. Эта модель применяется в Эстонии с 2003 г. в геодезии и других отраслях науки и техники. Новые данные высокоточной нивеляции, новые глобальные модели геопотенциала, а также гравиметрические данные создают предпосылки для обновления модели геоида и оценки его точности. Модель основана на гравиметрическом геоиде. Модель геоида Эстонии была вычислена быстрым методом Фурье с использованием всех гравиметрических данных и созданием сети 3×3 км. После использования новых гравиметрических данных в геоиде не оказалось значительного превышения высот по сравнению с точками, измеренными методом GPS. Среднеквадратическая погрешность составила 2,7 см. Вычисленная модель геоида была соединена с системой высот по точкам GPSнивелирования. Благодаря новым данным по высокоточной нивеляции, полученным в 2008–2010 гг., значительно увеличилось количество точек GPSнивелирования и тем самым увеличилась точность геоида, так как невязки полигонов нивелирования составляют всего 2–3 мм. Оценив точность нового геоида Эстонии, выявлено среднеквадратическое отклонение в 1,2 см.
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Pa’suya, M. F., A. H. M. Din, J. C. McCubbine, A. H. Omar, Z. M. Amin, and N. A. Z. Yahaya. "GRAVIMETRIC GEOID MODELLING OVER PENINSULAR MALAYSIA USING TWO DIFFERENT GRIDDING APPROACHES FOR COMBINING FREE AIR ANOMALY." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W16 (October 1, 2019): 515–22. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w16-515-2019.
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Abstract. We investigate the use of the KTH Method to compute gravimetric geoid models of Malaysian Peninsular and the effect of two differing strategies to combine and interpolate terrestrial, marine DTU17 free air gravity anomaly data at regular grid nodes. Gravimetric geoid models were produced for both free air anomaly grids using the GOCE-only geopotential model GGM GO_CONS_GCF_2_SPW_R4 as the long wavelength reference signal and high-resolution TanDEM-X global digital terrain model. The geoid models were analyzed to assess how the different gridding strategies impact the gravimetric geoid over Malaysian Peninsular by comparing themto 172 GNSS-levelling derived geoid undulations. The RMSE of the two sets of gravimetric geoid model / GNSS-levelling residuals differed by approx. 26.2 mm. When a 4-parameter fit is used, the difference between the RMSE of the residuals reduced to 8 mm. The geoid models shown here do not include the latest airborne gravity data used in the computation of the official gravimetric geoid for the Malaysian Peninsular, for this reason they are not as precise.
Dissertations / Theses on the topic "Geoid model"
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Guimarães, Gabriel do Nascimento. "A geoid model in the state of São Paulo: an attempt for the evaluation of different methodologies." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3138/tde-30072013-234021/.
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The purpose of this thesis is to compute and to evaluate the geoid model in the State of São Paulo from two methodologies (Stokes integral through the Fast Fourier Transform - FFT and Least Squares Collocation LSC). Another objective of this study is to verify the potentiality of GOCE-based. Therefore, a brief study about mathematical foundations and fundamentals of Physical Geodesy is carried out. Some features of the Global Geopotential Models (GGMs) are discussed, as well as an overview of the new gravimetric missions. A special attention is given to GOCE mission. The theory related to Stokes integral and Least Squares Collocation is also discussed in this work. The spectral decomposition was employed in the geoid models computation and the long wavelength component was represented by EGM2008 up to degree and order 150 and 360 and GOCE-based models up to 150. The models were compared in terms of geoid height residual and absolute and relative comparisons from GPS/leveling and the results show consistency between them. Also, a comparison in the mountain regions was carried out to verify the methodologies behavior in this area; the results showed that LSC is less consistent than FFT. Regarding GOCE-based models, 13 were tested, besides EGM2008. The evaluation was performed in terms of geoid height comparison obtained by GGMs over GPS/leveling and in terms of gravity disturbance. The evaluation shows that DIR _R3 and TIM_R3 presented more compatible results. The reason for the choice of São Paulo state is that there are a lot of geodetic activities and important engineering works that require the use of a height system. Furthermore, there are a lot of gravity and GPS/leveling data all around the state.Esta tese tem como propósito o cálculo e a avaliação do modelo geoidal no Estado de São Paulo a partir da aplicação de duas metodologias (integral de Stokes por meio da Transformada Rápida de Fourier FFT e a colocação por mínimos quadrados Least Squares Collocation LSC). Outro objetivo deste trabalho é verificar a potencialidade dos mais recentes Modelos Globais do Geopotential (MGGs) baseados nos dados do satélite GOCE. Para tanto, um breve estudo é realizado sobre os fundamentos matemáticos e os da Geodésia Física. Algumas características dos MGGs são discutidas, bem como uma visão global das novas missões gravimétricas. Uma atenção especial é dada a missão do satélite GOCE. A teoria referente à integral de Stokes e a colocação por mínimos quadrados são outros temas discutidos no trabalho. A decomposição espectral foi empregada no cálculo dos modelos geoidais e a componente de longo comprimento de onda foi representada pelo modelo EGM2008 até grau e ordem 150 e 360 e aqueles baseados na missão GOCE até 150. Os modelos foram comparados entre si em termos do resíduo da altura geoidal e na forma absoluta e relativa por meio das estações GPS/RN. Os resultados apontaram consistência entre os modelos em termos de diferença média quadrática. Também foi realizado um estudo na região montanhosa a fim de verificar o comportamento das metodologias; os resultados mostraram que a LSC é menos consistente do que a FFT. No que diz respeito aos modelos baseados na missão GOCE, 13 foram testados, além do EGM2008. A avaliação foi realizada em termos da comparação da altura geoidal obtidas pelos MGGs com as estações GPS/nivelamento e em termos do distúrbio de gravidade. A avaliação mostra que os modelos DIR_R3 e TIM_R3 apresentaram os resultados mais compatíveis. A escolha do estado de São Paulo está relacionada à grande quantidade de trabalhos geodésicos e atividades na área da engenharia e que necessitam da utilização de um sistema altimétrico. Além disso, a grande quantidade de dados gravimétricos e de estações GPS/RN é mais uma justificativa para a realização do trabalho.
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Danila, Uliana. "Mold2012 : a new gravimetric quasigeoid model over Moldova." Licentiate thesis, KTH, Geodesi och geoinformatik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105755.
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In order to be able to use the operational Moldavian GNSS Positioning System MOLDPOS efficiently for the determination of normal heights in surveying engineering, e.g. during the construction of a road, an accurate quasigeoid model is needed. The main goal of this thesis is to present a new gravimetric quasigeoid model for Moldova (Mold2012), which has been determined by applying the Least Squares Modification of Stokes’ formula with Additive corrections (LSMSA), also called the KTH method. Due to limited coverage of gravity data, the integration area is often limited to a small spherical cap around the computation point, which leads to a truncation error for geoid height. Molodensky et al. (1962) showed that the truncation error can be reduced by the modification of Stokes’ formula, where the measured gravity data are combined with the low-frequency component of the geoid from a Global Gravitational Model (GGM). The LSMSA technique combines the GGM and the terrestrial data in an optimum way. In order to find the most suitable modification approach or cap size it is necessary to compare the gravimetric height anomalies with the GPS/levelling derived height anomalies, and for this purpose we use a GPS/levelling dataset that consists of 1042 points with geodetic coordinates in the MOLDREF99 reference system and normal heights at the same points given in the height system Baltic 77. The magnitude of the additive corrections varies within an interval from -0.6 cm to -4.3 cm over the area of Moldova. The quasigeoid model which results from combining the ITG-Grace02s solution (with n = M = 170, ψ0 = 3° and σΔg = 10 mGal) and the solution obtained from the modified Stokes’ formula together with the additive correction gives the best fit for the GPS/levelling data with a standard deviation (STD) of ±7.8 cm. The evaluation of the computed gravimetric quasigeoid is performed by comparing the gravimetric height anomalies with the GPS/levelling derived height anomalies for 1042 points. However, the above heterogeneous data include outliers, and in order to find and eliminate these, a corrector surface model is used. This surface provides a connection to the local vertical when the GNSS technique is used. After the elimination of the suspicious outliers (170 points) according to a 2-RMS test, a new corrective surface was computed based on the remaining 872 GPS/levelling points, and the STD of residuals became ±4.9 cm. The STD value for the residuals according to the order of the levelling network for the Mold2012 fitted to the local vertical datum is 3.8 cm for the I-order, 4.3 cm for the II-order, 4.5 cm for the III-order and 5.0 cm for the IV-order levelling network. But the STD of the residuals for the 18 control points indicates a better result where the STD is 3.6 cm and RMS is 3.9 cm and the min and max value of residuals is -5.3 cm and 9.0 cm, respectively. As the STD of the differences in height anomaly are not just the standard error of the height anomalies (quasigeoid model), but it contains also the standard errors of GPS heights and of normal heights. Assuming that the latter STDs are 3 cm and 3.5 cm, respectively, the STD of Mold2012 is estimated to 1.7 cm.QC 20121127
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Inerbayeva, (Shoganbekova) Daniya. "Determination of a gravimetric geoid model of Kazakhstan using the KTH-method." Thesis, KTH, Geoinformatik och Geodesi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-52284.
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This study work deals with the determination of the gravimetric geoid model for Kazakhstan by using the KTH-method. A number of data sets were collected for this work, such as the gravity anomalies, high-resolution Digital Elevation Model (DEM), Global Geopotential Models (GGMs) and GPS/Levelling data. These data has been optimally combined through the KTH approach, developed at the Royal Institute of Technology (KTH) in Stockholm. According to this stochastic method, Stokes’ formula is being used with the original surface gravity anomaly, which combine with a GGM yields approximate geoid heights. The corrected geoid heights are then obtained by adding the topographic, downward continuation, atmospheric and ellipsoidal corrections to the approximate geoid heights. To compute the geoid model for Kazakhstan as accurately as possible with available data set different numerical tests have been performed: Choice of the best fit geopotential model in the computation area Investigations for the best choice of the initial condition for determination of the least-squares parameters Selection of the best parametric model for reducing the effect of the systematic error and data inconsistencies between computed geoid heights and GPS/Levelling heights. Finally, 5'x5' Kazakh gravimetric geoid (KazGM2010) has been modelled.
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Abdalla, Ahmed. "Determination of a gravimetric geoid model of Sudan using the KTH method." Thesis, KTH, Geodesi och satellitpositionering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199670.
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The main objective of this study is to compute a new gravimetric geoid model of Sudan using the KTH method based on modification of Stokes’ formula for geoid determination. The modified Stokes’ formula combines regional terrestrial gravity with long-wavelength gravity information provided by the global gravitational model (GGM). The collected datasets for this study contained the terrestrial gravity measurements, digital elevation model (DEM), GPS/levelling data and four global gravitational Models (GGMs), (EGM96, EIGEN-GRACE02S, EIGEN-GL04C and GGM03S). The gravity data underwent cross validation technique for outliers detection, three gridding algorithms (Kriging, Inverse Distance Weighting and Nearest Neighbor) have been tested, thereafter the best interpolation approach has been chosen for gridding the refined gravity data. The GGMs contributions were evaluated with GPS/levelling data to choose the best one to be used in the combined formula. In this study three stochastic modification methods of Stokes’ formula (Optimum, Unbiased and Biased) were performed, hence an approximate geoid height was computed. Thereafter, some additive corrections (Topographic, Downward Continuation, Atmospheric and Ellipsoidal) were added to the approximated geoid height to get corrected geoid height. The new gravimetric geoid model (KTH-SDG08) has been determined over the whole country of Sudan at 5′ x 5′ grid for area ( 4 ). The optimum method provides the best agreement with GPS/levelling estimated to 29 cm while the agreement for the relative geoid heights to 0.493 ppm. A comparison has also been made between the new geoid model and a previous model, determined in 1991 and shows better accuracy. ≤φ ≤ 23 , 22 ≤ λ ≤ 38 Keywords: geoid model, KTH method, stochastic modification methods, modified Stokes’ formula, additive corrections.
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Daras, IIias. "Determination of a gravimetric geoid model of Greece using the method of KTH." Thesis, KTH, Geodesi och satellitpositionering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199682.
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The main purpose of this study is to compute a gravimetric geoid model of Greeceusing the least squares modification method developed at KTH. In regional gravimetricgeoid determination, the modified Stokes’s formula that combines local terrestrial datawith a global geopotential model is often used nowadays.In this study, the optimum modification of Stokes’s formula, introduced by ProfessorSjöberg, is employed so that the expected mean square error (MSE) of all possiblesolutions of the general geoid model is minimized. According to this stochasticmethod, the Stokes’s formula is being used with the original surface gravity anomalywhich combined with a GGM yields an approximate geoid height. The corrected geoidheight is then obtained by adding the topographic, downward continuation,atmospheric and ellipsoidal corrections to the approximate geoid height.The dataset used for the computations, consisted of terrestrial gravimetricmeasurements, a DEM model and GPS/Levelling data for the Greek region. Threeglobal geopotential models (EGM96, EIGEN-GRACE02S, EIGEN-GL04C) weretested for choosing the best GGM to be combined into the final solution. Regarding theevaluation and refinement of the terrestrial gravity measurements, the cross-validationtechnique has been used for detection of outliers.The new Greek gravimetric geoid model was evaluated with 18 GPS/Levelling pointsof the Greek geodetic network. The absolute agreement between the gravimetric andthe GPS/Levelling geoid height was estimated at 27 cm while the relative agreement at0.9 ppm. In a case of study the absolute accuracy of the model was estimated at 14 cm.The geoid model computed in this study was also compared with some previous Greekgeoid models, yielding better external accuracy than them.
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Berntsson, Jenny. "A study on the quality of the NKG2015 geoid model over the Nordic countries." Thesis, Högskolan Väst, Avdelningen för Matematik, Data- och Lantmäteriteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-13960.
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Geoidmodellen NKG2015 (Nordiska kommissionen för geodesi) är den senaste geoidmodellen över Norden. Det har inte publicerats någon forskning om kvaliteten på den här nya modellen, därför kan den här studien bidra till forskningen inom ämnet. Det är viktigt att vara medveten om begränsningarna och kvaliteten på den geoidmodell som används vid mätning av höjder. Om kvaliteten på geoidmodellen inte är känd så kommer kvaliteten på höjdmätningarna inte heller att vara känd. Detta kan skapa problem när mätningarna används i projekt där precision är viktigt. För att undersöka kvaliteten på geoidmodellen NKG2015 har geoidhöjderna beräknade från modellen jämförts med geoidhöjder som fås från mätning med metoden GNSS (Global Navigation Satellite Systems) /avvägning vid samma punkter. Slutningsfelet mellan geoidhöjderna från geoidmodellen och geoidhöjderna från mätningarna har analyserats med statistiska metoder. Slutningsfelens normalitet testas och analysen utförs på ofiltrerad data samt data som filtrerats med två olika konfidensintervall, 95% och 99,7%. Detta för att filtrera bort eventuella avvikande värden. Eventuella trender i datan jämnas ut med en metod baserad på minsta kvadratmetoden. Studiens resultat visar att filtrering av slutningsfelen generellt gör datan mer normalfördelad, men så är inte fallet för alla länder. I de flesta fall förbättras normaliteten även genom att jämna ut trender i datan. I processen med att jämna ut trender används en korrigerande yta med ett specificerat antal parametrar. Topografin i varje land spelar en stor roll när beslut ska fattas om hur många parametrar som behövs i den korrigerande ytan. Länder med höga berg och stora höjdskillnader så som Norge har en större osäkerhet i datan och kräver fler parametrar i den korrigerande ytan. Danmark är ett land med relativ platt topografi och behöver inte lika många parametrar i den korrigerande ytan som Norge för att effektivt jämna ut trender. Det finns givna värden på felen för datan som är uppmätt med GNSS/avvägning, dessa fel stämmer generellt inte överens med slutningsfelen. För Finland är det givna felet för GNSS/avvägning större än det borde vara medan felen för GNSS/avvägning i de andra länderna är något mindre än vad slutningsfelen antyder. De givna, uppskattade felen för geoidmodellen NKG2015 är 10 mm för Sverige och Danmark, 22 mm för Norge och 12 mm för Finland. Dessa fel är rimliga men stämmer inte helt överens med de givna felen för GNSS/avvägning i relation till slutningsfelen. Under antagandet att de givna felen för GNSS/avvägning är korrekta kan följande konfidensintervall uppskattas för geoidfelen; 06,5mm för Sverige, 1,8-5,2mm för Danmark, 14,8-17,7mm för Norge och 0-0mm för Finland.The NKG2015 (Nordic Geodetic Commission) geoid model is the most recent official geoid model over the Nordic countries. There has been no previous research published on the quality of this model, therefore, this study may be a valuable contribution to the research in this area. It is important to be aware of the limitations and quality of the geoid model used when measuring heights. If the quality of the geoid is not known, the quality of the measured heights will also be uncertain. This might cause problems when the measured heights are used in projects where great precision is vital. Measured GNSS (Global Navigation Satellite Systems)/levelling data has been compared to the computed geoid heights from the NKG2015 geoid model at the corresponding points to investigate the quality of this model. The misclosures between the geoid height, obtained from the GNSS/levelling data and the geoid heights from the NKG2015 geoid model have been analysed by statistical methods. The normality of the misclosures is tested, and the analysis is performed on unfiltered and filtered misclosures with confidence intervals (CIs) of 95% and 99.7% to remove probable outliers. Trends in the misclosures are removed with a least-squares detrending method. The result of the study shows that filtering the misclosures generally makes them more normally distributed, but this is not the case for all countries. Detrending the misclosures improves the normality in most cases. In this process, a corrective surface with a specified number of parameters is fitted to the misclosures to remove trends. The topography of each country is very important when deciding which corrective surface that should be used in the detrending process. Countries with rough topography such as Norway has greater uncertainty in its heights and needs a corrective surface with more parameters than flatter countries such as Denmark. There are some estimates for the errors for the GNSS/levelling data which are not all in agreement with the misclosures. The GNSS/levelling error in Finland is greater than it should be. The given, estimated errors of the NKG2015 geoid model are 10 mm for Sweden and Denmark, 22 mm for Norway and 12 mm for Finland. These errors are reasonable, but not in perfect agreement with the given errors of the GNSS/levelling measurements in relation to the misclosures. Based on the assumption that the GNSS/levelling errors are correct, confidence intervals of the geoid error can be estimated. These estimated intervals are 0-6.5mm for Sweden, 1.8-5.2mm for Denmark, 14.8-17.7mm for Norway and 0-0mm for Finland. The confidence interval for Finland is not realistic because it is based on the assumption that the GNSS/levelling error is correct.
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Nunes, Vagner Conceição. "Testes sobre a eficiência do modelo do geopotencial EGM2008 na cidade de Porto Alegre." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26992.
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Este estudo apresenta o teste da eficiência do Earth Global Model 2008 (EGM2008) na geração de um modelo geoidal local, através da compatiblização com a ondulação obtida por posicionamento GPS (Global Positioning System) em 63 Referências de Nível (RN’s) localizadas no município de Porto Alegre, Rio Grande do Sul. O objetivo geral da dissertação foi analisar a exatidão do modelo geoidal gerado a partir dos coeficientes do modelo geopotencial EGM2008 para nivelamento por GPS no município de Porto Alegre e os objetivos específicos foram: a avaliação do modelo na região de Porto Alegre, a comparação das ondulações geoidais do EGM2008 (NEGM2008) com as ondulações geoidais em 63 RN’s (NGPS), o ajustamento da componente sistemática do geoide que é a diferença entre NEGM2008 e NGPS e a geração do modelo geoidal local compatibilizado para Porto Alegre. O método adotado apresenta as seguintes etapas: cálculo das ondulações geoidais nas RN’s; eliminação de erros grosseiros; geração do modelo geoidal através dos dados do EGM2008 com resolução de 7” de arco; cálculo da componente sistemática do geoide; ajustamento da componente sistemática através de transformação por polinômio de 2° grau com seis parâmetros pelo Método dos Mínimos Quadrados (MMQ). Os resultados obtidos foram: os parâmetros que compatibilizam o modelo geoidal global com o local e modelo geoidal local compatibilizado no formato raster, contendo as ondulações geoidais para todo o município. O novo modelo apresentou erro médio de 1,9 cm e desvio padrão de 7,2 cm. Os resultados da dissertação confirmam que é possível reduzir o erro associado ao modelo global através dos procedimentos adotados. Dessa maneira, conclui que o método utilizado reduziu o valor médio da componente sistemática de 15,4 cm para 1,9 cm após o ajustamento.This study presents the Earth Global Model 2008’s (EGM2008) efficiency test on the conception of a local geoid model. The results were acquired through the undulation compatibility obtained by GPS (Global Positioning System) in 63 Bench Mark (BM) located in Porto Alegre, Rio Grande do Sul state, Brazil. The aim of this research was to analyze the accuracy of the geoid model generated from the geopotential model EGM2008’s coefficients to GPS leveling in Porto Alegre. The specific goals were the evaluation of the model in Porto Alegre region’s, the comparison between the EGM2008 (NEGM2008) geoid undulations and the geoid undulations in 63 BM (NGPS), and the adjustment of geoid’s systematic component, that is the difference between NEGM2008 and NGPS and the local geoid model’s conception to Porto Alegre. The method used presents the following steps: geoid undulation on RN’s’s computation; elimination of gross errors; geoid model’s conception through EGM2008’s data with resolution of 7” of arch; geoid’s systematic component computation; adjustment of the systematic component through transformation of 2nd degree polynomial with six parameters by the method of Least Squares. The results were: the parameters that make the models global and local compatible, and local geoid model compatible in raster format, containing the geoid undulations for the entire municipality. The new model showed 1.9 of mean error and 7.2 cm of standard deviation. Through the procedures adopted, the dissertation results’ confirm that it is possible to reduce the error associated of the the global model. Therefore, the conclusion is that the method used reduced the mean error of the systematic component from 15,4 cm to 1.9 cm, after the adjustment.
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Ulotu, Prosper E. "Geoid model of Tanzania from sparse and varying gravity data density by the KTH method /." Stockholm : Skolan för Arkitektur och samhällsbyggnad, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10270.
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Ulotu, Prosper. "Geoid Model of Tanzania from Sparse and Varying Gravity Data Density by the KTH method." Doctoral thesis, KTH, Geodesi (stängd 20110301), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10270.
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Developed countries are striving to achieve a cm geoid model. Most developing countries/regions think that the situation in their areas does not allow even a few decimetre geoid model. GNSS, which provides us with position, is one of the greatest achievements of the present time. Conversion of ellipsoidal height to orthometric height, which is more useful, requires an accurate geoid model. In spite of the sparse terrestrial gravity data of variable density, distribution and quality (a typical situation in developing countries), this study set out to develop as accurately as possibly achievable, a high quality geoid model of Tanzania. Literature review of three more preferred geoid methods came to a conclusion, that the Royal Institute of Technology of Sweden (KTH) method of least squares modification of Stokes formula (LSMS) with additive corrections (AC) is the most suitable for this research. However, even with a good method, the accuracy and the quality of a geoid model depend much on the quality of the data. In this study, a procedure to create a gravity database (GDB) out of sparse data with varying density, distribution and quality has been developed. This GDB is of high density and full coverage, which ensures presence of high and low gravity frequencies, with medium frequencies ranging between fair and excellent. Also an alternative local/regional Global Gravitational Model (GGM) validation method based on quality terrestrial point surface gravity anomaly has been developed. Validation of a GGM using the new approach of terrestrial point gravity and GPS/Levelling, gave the same results. Once satisfactorily proved, the method has extra advantages. The limits of Tanzania GDB (TGDB) are latitudes 15 ° S to 4 ° N and longitudes 26 ° E to 44 ° E . Cleaning and quality control of the TGDB was based on the cross validation (XV) by the Kriging method and Gaussian distribution of the XV residuals. The data used in the LSMS with AC to develop a new Tanzania gravimetric geoid model 2008, TZG08, are 1′ ×1′ clean and statistically tested surface gravity anomalies. 39,677 point gravity in land and 57,723 in the ocean were utilised. Pure satellite ITGGRACE03S GGM to degree 120 was used to determine modification parameters and long-wavelength component of the geoid model. 3′′ Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM), ITG-GRACE03S to degree 120 and EIGENCG03C to degree 360 combined GGM qualified to patch the data voids in accordance to the method of this research. TZG08 is referred to Geodetic Reference System 1980 (GRS80), and its extents are latitudes 12 ° S to 1 ° N and longitudes 29 ° E to 41 ° E . 19 GPS/levelling points qualified to assess the overall accuracy of TZG08 as 29.7 cm, and upon approximate removal of GPS and orthometric systematic effects, the accuracy of TZG08 is 27.8 cm. A corrector surface (CS) for conversion of GPS height to orthometric height referred to Tanzania National Height Datum (TNHD) has been created for a part of TZG08. Using the CS and TZG08, orthometric height of Mt. Kilimanjaro is re-established as it was in 1952 to be 5,895 m above the TNHD, which is still the official height of the mountain.QC 20100813
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Ssengendo, Ronald. "A height datum for Uganda based on a gravimetric quasigeoid model and GNSS/levelling." Doctoral thesis, KTH, Geodesi och satellitpositionering, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-172547.
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This study is devoted to the determination of a high resolution gravimetric geoid model for Uganda based on the optimal combination of terrestrial and satellite gravity anomalies using the method of Least Squares Modification of Stokes’ formula with additive corrections. Specifically the study investigates the current status of the existing Uganda Vertical Network relative to the requirements of a modern height datum and includes a detailed evaluation and validation of terrestrial gravity data, several digital elevation models and some recent global geopotential models. Finally a new height datum based on a gravimetric quasigeoid model and Global Navigation Satellite Systems (GNSS)/levelling is proposed. In this thesis, the Uganda Gravimetric Geoid Model 2014 (UGG2014) is computed from several datasets which, include 7839 terrestrial gravity data points from the International Gravimetric Bureau, the 3 arc second Shuttle Radar Topography Mission digital elevation model and a recent Gravity field and steady-state Ocean Circulation Explorer-only global geopotential model. To compensate for the missing gravity data in the target area, the surface gravity anomalies extracted from the World Gravity Map 2012 were used. Outliers in the terrestrial gravity data were detected using the cross-validation technique which, also estimated the accuracy of the remaining terrestrial gravity data as 9 mGal. Based on 12 GNSS/levelling data points distributed over Uganda, the root mean square fit of UGG2014 before and after the 4-parameter fit is 16 cm and 9 cm, respectively. The study has revealed that the heights of the Uganda Vertical Network are normal-orthometric heights for which the quasigeoid is the closest approximation to the zero reference surface. Consequently, the Uganda Gravimetric Quasigeoid Model 2014 (UGQ2014) was derived from the UGG2014 with the quasigeoid-geoid separation computed from the Earth Gravitational Model 2008 complete to degree/order 2160 of spherical harmonics. The root mean square fit of UGQ2014 versus GNSS/levelling is 15 cm and 8 cm before and after the 4-parameter fit, respectively, which shows that the quasigeoid model fits GNSS/levelling better than the geoid model. Thus a new height datum based on UGQ2014 and GNSS/levelling was determined as a practical solution to the determination of heights directly from GNSS. Evaluated with 4 independent GNSS/levelling points, the root mean square fit of the new height datum is 5 cm better than using the quasigeoid model alone. With an average parts-per-million of 29 in the relative test, the new height datum satisfies the precision and accuracy requirements of third order precise levelling. Overall, the results show that UGG2014 and UGQ2014 agree considerably better with GNSS/levelling than any other recent regional/global gravimetric geoid models. Therefore, both gravimetric solutions are a significant step forward in the modelling of a “1-cm geoid” over Uganda given the poor quality and quantity of the terrestrial gravity data used for computation.QC 20150831
Book chapters on the topic "Geoid model"
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Kahar, J., A. Kasenda, and K. Prijatna. "The Indonesian Geoid Model 1996." In International Association of Geodesy Symposia, 613–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-03482-8_81.
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Font, Graciela, María Cristina Pacino, Denizar Blitzkow, and Claudia Tocho. "A Preliminary Geoid Model for Argentina." In Geodesy on the Move, 255–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-72245-5_37.
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Véronneau, Marc. "The GSD95 Geoid Model for Canada." In International Association of Geodesy Symposia, 573–80. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-03482-8_76.
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Berry, P. A. M., R. G. Smith, and J. Benveniste. "ACE2: The New Global Digital Elevation Model." In Gravity, Geoid and Earth Observation, 231–37. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10634-7_30.
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Kuroishi, Y. "A New Geoid Model for Japan, JGEOID2000." In Gravity, Geoid and Geodynamics 2000, 329–33. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-662-04827-6_55.
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Bašić, Tomislav, and Olga Bjelotomić. "HRG2009: New High Resolution Geoid Model for Croatia." In Gravity, Geoid and Height Systems, 187–91. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-10837-7_24.
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Font, G., and C. Tocho. "Preliminary Geoid Model for Tierra del Fuego." In International Association of Geodesy Symposia, 194–96. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04683-8_37.
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Piñón, D. A., K. Zhang, S. Wu, and S. R. Cimbaro. "A New Argentinean Gravimetric Geoid Model: GEOIDEAR." In International Symposium on Earth and Environmental Sciences for Future Generations, 53–62. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/1345_2017_267.
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Ellmann, A. "Validation of the New Earth Gravitational Model EGM08 Over the Baltic Countries." In Gravity, Geoid and Earth Observation, 489–96. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10634-7_65.
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Daras, I., H. Fan, K. Papazissi, and J. D. Fairhead. "Determination of a Gravimetric Geoid Model of Greece Using the Method of KTH." In Gravity, Geoid and Earth Observation, 407–13. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10634-7_54.
Full textConference papers on the topic "Geoid model"
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Sulaiman, S. A. H., K. H. Talib, M. A. M. Wazir, and O. M. Yusof. "Evaluation of geoid height derived by geopotential model and existing regional geoid model." In 2013 IEEE 9th International Colloquium on Signal Processing & its Applications (CSPA). IEEE, 2013. http://dx.doi.org/10.1109/cspa.2013.6530024.
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Shoganbekova, Daniya. "GRAVIMETRIC GEOID MODEL OVER KAZAKHSTAN." In 15th International Multidisciplinary Scientific GeoConference SGEM2015. Stef92 Technology, 2011. http://dx.doi.org/10.5593/sgem2015/b22/s9.035.
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Janpaule, Inese. "Application of KTH method for determination of latvian geoid model." In Proceedings of the International Conference „Innovative Materials, Structures and Technologies”. Riga: Riga Technical University, 2014. http://dx.doi.org/10.7250/iscconstrs.2014.11.
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Yada, Tatsuya, Tatsuo Nobe, and Masanari Ukai. "Application of KTH method for determination of latvian geoid model." In Advanced HVAC and Natural Gas Technologies. Riga: Riga Technical University, 2015. http://dx.doi.org/10.7250/rehvaconf.2015.011.
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Milbert, Dennis G. "GEOID90: High‐resolution geoid height model for the conterminous United States." In SEG Technical Program Expanded Abstracts 1992. Society of Exploration Geophysicists, 1992. http://dx.doi.org/10.1190/1.1822155.
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"High Resolution Technology of Shuttle Radar Topography Mission for Geoid Model." In March 2017 Singapore International Conferences. EAP, 2017. http://dx.doi.org/10.17758/eap.eap317418.
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Birylo, Monika, and Katarzyna Pajak. "Statistical Approach to the Computation of an Influence of the Yangtze Dam on Gravity Fluctuations." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.165.
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Due to the realization of the Three Gorges Dam on the Yangtze River and its content of 40 billion tons of water many geodynamical consequences can still be observed. It is obvious that global geodynamical changes are noticeable at whole basin of the Yangtze river. Such changes can be observed by the GRACE (Gravity Recovery and Climate Experiment) gravimetric satellites (Ilk et al. 2005). The GRACE gravity field model data are available in the form of spherical harmonic expansion; by defining a specific filter, one can compute geoid variations at specific locations. As a reference, EGM2008 model was used, on its basis geoid variations were determined. According to the results, geoid variations at the Yangtze river become more stable after filling the Dam. In the article a statistical methods were used for the purpose of the evaluation of a differences EGM08-GRACE time series in the area of the Three Gorges Dam. In the article the authors want to present trend analysis and short-term forecasting with ARIMA model usage.
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"Development of Geoid Model for Chhattisgarh State using Geophysical Methods and GPS Technology." In 4th International Conference on Advances in Engineering Sciences and Applied Mathematics. International Institute of Engineers, 2015. http://dx.doi.org/10.15242/iie.e1215013.
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Erina Ariff, Nur Sofia, Adolfientje Kasenda Olesen, Norehan Md Yaacob, and Saiful Aman Hj Sulaiman. "Evaluation of Gravity Anomaly and Geoid Height Derived from Various Global Geopotential Model." In 2021 IEEE 12th Control and System Graduate Research Colloquium (ICSGRC). IEEE, 2021. http://dx.doi.org/10.1109/icsgrc53186.2021.9515205.
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Pereira Dos Santos, Newton, Iris Pereira Escobar, and Carlos Andrés Bonilla Quintero. "The Egm08 Model And Srtm Data For The Gravimetric Geoid Using Voronoi/Delaunay Discretisation." In 11th International Congress of the Brazilian Geophysical Society. European Association of Geoscientists & Engineers, 2009. http://dx.doi.org/10.3997/2214-4609-pdb.195.1837_evt_6year_2009.
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