Wyniki wyszukiwania - BazTech

1

Comparison of Selected Geopotential Models in Terms of the GOCE Orbit Determination Using Simulated GPS Observations

Bobojć A.

Acta Geophysica

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2016

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Vol. 64, no. 6

2761--2780

EN

This work contains a comparative study of the performance of six geopotential models in an orbit estimation process of the satellite of the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) mission. For testing, such models as ULUX_CHAMP2013S, ITG-GRACE 2010S, EIGEN-51C, EIGEN5S, EGM2008, EGM96, were adopted. Different sets of pseudo-range simulations along reference GOCE satellite orbital arcs were obtained using real orbits of the Global Positioning System satellites. These sets were the basic observation data used in the adjustment. The centimeter-accuracy Precise Science Orbit (PSO) for the GOCE satellite provided by the European Space Agency (ESA) was adopted as the GOCE reference orbit. Comparing various variants of the orbital solutions, the relative accuracy of geopotential models in an orbital aspect is determined. Full geopotential models were used in the adjustment process. The solutions were also determined taking into account truncated geopotential models. In such case, an accuracy of the solutions was slightly enhanced. Different arc lengths were taken for the computation.

2

Geoid in the area of Poland in the author's investigations

Łyszkowicz A.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2012

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nr 15(1)

49-64

EN

The present paper describes the results of the author's work related to the geoid determination in the area of Poland. Beginning from the geoid model geoid92 worked out in 1992, various geoid models calculated from various data sets, using various methods, are presented. Additionally, the evaluation of the accuracy of the determined geoid models is given. Next, the necessity of the fitting of computed geoid models to the national vertical reference system and the evaluation of the accuracy of the functionals N, Δg, ξ, η of the gravity field calculated from the various geopotential models are presented. It results from the presented investigations, that at present the accuracy of gravimetric geoid/quasigeoid models is ± 1.4 cm and accuracy of geoid computed from geopotential model EGM08 is ± 2.4 cm. It is stated additionally that accuracy of gravity anomalies computed from the EGM08 model is ± 25 µm s-2 , while accuracy of the deflections of the vertical ξ and η is from ± 0.6'' to ± 0.7''.

PL

W pracy przedstawiono wyniki badań dotyczących przebiegu geoidy na obszarze Polski. Poczynając od modelu geoid92, opracowanego w 1992 roku, w artykule przestawiono kolejne modele geoidy liczone z różnych danych i różnymi metodami wraz z ich charakterystyką dokładnościową. Uzasadniono konieczność dopasowania wyliczonych modeli geoidy do krajowego układu wysokościowego oraz podano dokładności charakterystyk pola siły ciężkości N, Δg, ξ, η obliczanych z kolejnych modeli geopotencjału. Z wyników badań wynika, że obecnie dokładność grawimetrycznych modeli geoidy/quasi-geoidy wynosi ± 1,4 cm, a dokładność geoidy wyliczonej z modelu geopotencjału EGM08 ± 2,4 cm. Dodatkowo stwierdzono, że dokładność anomalii grawimetrycznych wyliczonych z modelu EGM08 wynosi ± 25 µm s-2, a dokładność składowych odchyleń pionu ξ i η od ± 0.6'' do ± 0.7''.

3

Time variations of the gravity ﬁeld over Europe obtained from GRACE data

Kloch-Glowka G., Krynski J., Szelachowska M.

Reports on Geodesy

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2012

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z. 1/92

175--190

EN

Time variations of the gravity field derived from time series of geopotential model developed from GRACE data can be interpreted in terms of geoid heights, and mass time variations with unprecedented temporal resolution. Following the results of authors previous research presented at 2nd General Assembly of the IGFS, 20-22 September 2010, Fairbanks, Alaska, the series of monthly solutions of geopotential models developed from GRACE data in JPL, filtered with the use of DKK1 filter, and GLDAS hydrological model were used in the analyses. Variations of hydrology as well as variations of geoid heights for the period August 2002 – June 2010 at the continental part of Europe and selected 14 subareas were estimated with spatial resolution of 0.5° x 0.5° . Variations in mass distribution obtained from geopotential models were compared with the respective results obtained from hydrological data. Models of geoid height changes (parameters of trend and seasonal variations) were determined for the area of Europe and for 14 subareas. To verify models of geoid height changes, over the period July 2010 - October 2010 values of geoid height changes calculated using GRACE data were compared with values based on the models developed.

4

Application of the global geopotential models for determination of the levelling normal correction

Marganski S., Kalinczuk-Stanałowska K., Olszak T.

Reports on Geodesy

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2010

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z. 1/88

115-120

EN

Vertical networks in Poland are processed in the normal heights system called Kronstatt'86. Levelling evaluation of high precision measurements requires a determinations of normal levelling corrections, based on gravity Faye's anomalies. The purposes of the paper is to analyze the possibility of using in this computations the anomalies generated from global geopotential models while maintaining accuracy analysis which indicate a possible accuracy of Faye's anomalies. Author have compared gravity anomalies obtained directly from measurements with gravity anomalies generated from different global geopotential models EGM96, PGM96, EGM2008. Authors have prospered an algorithm of gravity anomalies computation on geoid surface after free-air moving anomalies from geopotential models. Comparison was made on points of vertical network located in medium-hill areas (around Starachowice near Kielce) and lowland (around Gostyn and Grudziadz) and on others test fields in Poland. The ability to use the geopotential models depends on their resultation. As a result of analysis concluded that only in the plain and lowland areas is possible to use data from global geopotential models with resolution above degree 720.