On the adjustment of combined GPS/levelling/geoid networks

Kotsakis, C.; Sideris, M. G.

doi:10.1007/s001900050261

Cited by 131 publications

(26 citation statements)

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“…In the same way, GPS and leveling data have been used, in combination with gravity data, to derive highresolution gravimetric geoids (Kotsakis and Sideris, 1999;Duquenne, 1999;Denker et al, 2000;Duquenne et al, 2005;Nahavandchi and Soltanpour, 2006). Using clocks is, however, different from performing GPS and leveling measurements.…”

Section: Discussionmentioning

confidence: 99%

Determination of a high spatial resolution geopotential model using atomic clock comparisons

Lion

Panet

Wolf

et al. 2017

J Geod

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Recent technological advances in optical atomic clocks are opening new perspectives for the direct determination of geopotential differences between any two points at a centimeter-level accuracy in geoid height. However, so far detailed quantitative estimates of the possible improvement in geoid determination when adding such clock measurements to existing data are lacking. We present a first step in that direction with the aim and hope of triggering further work and efforts in this emerging field of chronometric geodesy and geophysics. We specifically focus on evaluating the contribution of this new kind of direct measurements in determining the geopotential at high spatial resolution (≈10 km). We studied two test areas, both located in France and corresponding to a middle (Massif Central) and high (Alps) mountainous terrain. These regions are interesting because the gravitational field strength varies greatly from place to place at high spatial resolution due to the complex topography. Our method consists in first generating a synthetic high-resolution geopotential map, then drawing synthetic measurement data (gravimetry and clock data) from it, and finally reconstructing the geopotential map from that data using least squares collocation. structed map is then assessed by comparing it to the original one used to generate the data. We show that adding only a few clock data points (less than 1% of the gravimetry data) reduces the bias significantly and improves the standard deviation by a factor 3. The effect of the data coverage and data quality on the results is investigated, and the tradeoff between the measurement noise level and the number of data points is discussed.

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Section: Discussionmentioning

confidence: 99%

Determination of a high spatial resolution geopotential model using atomic clock comparisons

Lion

Panet

Wolf

et al. 2017

J Geod

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“…A critical review of different types of VCE can be found in Fotopoulos (2003) and van Loon (2008). Contemporary applications include GPS positioning time series, network analysis (Amiri-Simkooei 2009), regional GPS/levelling/geoid datum unification (Kotsakis and Sideris 1999) and satellite gravimetry data analysis (van Loon 2008). The application of VCE should warrant continuous application, given multiple data sources from different satellites, airborne and ground-based measurements, along with better computational resources.…”

Section: Vce Techniquementioning

confidence: 99%

Data fusion of multisatellite altimetry for ocean tides modelling: a spatio-temporal approach with potential oceanographic applications

Fok

2015

International Journal of Image and Data Fusion

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To cite this article: Hok Sum Fok (2015) Data fusion of multisatellite altimetry for ocean tides modelling: a spatio-temporal approach with potential oceanographic applications, International Journal of Image and Data Fusion, 6:3, 232-248, Nowadays, data combination/fusion is a common practice to integrate multiple data sources into a spatially and/or temporally regular data set for facilitating analysis and interpretation. Given the advancement in active remote sensing for monitoring our changing environment (no matter ocean, land or ice), the data acquisition from various spaceborne platforms with different spatio-temporal resolutions is enormous; calling for a need of multisatellite data combination. Instead of equally or spatially weighted solution, this article illustrates a spatio-temporal combination approach that weights data both in space and in time simultaneously for ocean tide modelling using multisatellite altimetry data sets under different spatial and temporal resolutions. The tide models generated from this approach show substantial improvement near coastal regions when compared to other contemporary ocean tide models by using independent pelagic and coastal tide gauges serving as ground truth. The discrepancy of the best model is~23%, three times larger than that of the deep ocean. Further improvement lies in more and better spatio-temporal observations in the near future. We anticipate this approach can be applied to other spatio-temporal data in a similar settings for spatio-temporal dependent unknown parameters, including geodetic, geophysical, oceanographic data and imagery under different spatial and temporal resolutions.

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“…From the last decade of the twentieth century different aspects of fitting a continuous surface to discrete GPS/leveling data have been studied, and different techniques have been used for many case studies. Among them, the reader may at least be referred to the inverse distance weighting (Erol and Çelik 2005; Zhan-ji and Yong-qi 1999), multivariable polynomial regression equations (MPREs) (Georgopoulos and Telioni 2015;Zhong 1997), geostatistical kriging (Erol and Çelik 2005), least-square collocation (Brown et al 2011;Featherstone and Sproule 2006;Featherstone et al 2011;Kotsakis and Sideris 1999;Tscherning et al 2001), artificial neural networks (ANNs) (Erol and Erol 2013;Kavzoglu and Saka 2005), and the adaptive neuro fuzzy inference system (ANFIS) (Erol and Erol 2013).…”

Section: Introductionmentioning

confidence: 99%

Combination of GPS and Leveling Observations and Geoid Models Using Least-Squares Variance Component Estimation

et al. 2017

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In the last few years, satellite-based positioning techniques, such as the Global Positioning System (GPS), proved their abilities in various geodetic fields. Height determination, as one of such applications, requires a more likely correct geoid model to provide reliable geoid heights for transformation of the ellipsoidal heights to orthometric heights. An important step is then to establish such a model by optimal combination of the available geoid models. This can be achieved via variance component estimation (VCE) methods, which provide appropriate weights to GPS and leveling observations as well as the geoid models. The authors demonstrate the efficacy of the least-squares VCE (LS-VCE) to this problem. The algorithm is applied to real data sets in Shahin-Shahr, Isfahan, Iran, to evaluate the EGM2008 and GGMplus Earth geopotential models and a regional geoid model (named IRGeoid10) in terms of agreement to the GPS/leveling observations and introduce the more likely correct model over the case-study area. The results indicate that the EGM2008 model shows a good agreement (2-mm precision on the fitted surface) with the results of the GPS/leveling observations in this very small area. It is notable, however, that the present contribution is mainly of interest from an algorithmic point of view because concrete conclusions cannot be made when comparing the results due to the small case-study area used. By optimal combination of these data sets, the weights of which are estimated by LS-VCE, a geometric surface is presented to approximate the local vertical datum in the case-study region. This surface can convert the ellipsoidal heights, which can be obtained from GPS, to the orthometric heights with high precision. individual papers. This paper is part of the Journal of Surveying Engineering, © ASCE, ISSN 0733-9453. © ASCE 04016023-1 J. Surv. Eng. J. Surv. Eng., 04016023 Downloaded from ascelibrary.org by Vahab Nafisi on 07/31/16. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04016023-9 J. Surv. Eng. J. Surv. Eng., 04016023 Downloaded from ascelibrary.org by Vahab Nafisi on 07/31/16. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04016023-11 J. Surv. Eng. J. Surv. Eng., 04016023 Downloaded from ascelibrary.org by Vahab Nafisi on 07/31/16.

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On the adjustment of combined GPS/levelling/geoid networks

Cited by 131 publications

References 0 publications

Determination of a high spatial resolution geopotential model using atomic clock comparisons

Determination of a high spatial resolution geopotential model using atomic clock comparisons

Data fusion of multisatellite altimetry for ocean tides modelling: a spatio-temporal approach with potential oceanographic applications

Combination of GPS and Leveling Observations and Geoid Models Using Least-Squares Variance Component Estimation

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