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1
Content available Reprocessing of GPS and repeated absolute gravity measurements realized in Tatra mountain
Mojzes M., Papko J., Mikolaj M.
Reports on Geodesy
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2012
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z. 2/93
41--47
2
Content available remote Research on absolute gravity variations in geodynamic laboratory in Książ in the period of 2007-2011
Kaczorowski M., Olszak T., Walo J., Barlik M.
Artificial Satellites : Journal of Planetary Geodesy
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2012
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Vol. 47, No. 4
169--176
EN
In 2006 a gravimetric pavilion was installed inside the Geodynamic Laboratory (LG) in Książ. The pavilion was equipped with two pillars intended to serve relative and absolute gravimetric measurements. Installation of measurement platform for absolute gravity measurements inside gravimetric pavilion of LG made it possible to perform four sessions of absolute gravity measurements: two of them in 2007 (June 10-12 and Nov. 21-22), one in 2008 (Apr. 21-22) and one in 2011 (June 19-21). In 2007 the absolute measurements were performed using two FG5 ballistic gravimeters. In April 2007 the measurements were performed by Dr Makinen from Geodetic Institute of Finnish Academy of Science with application of FG5 No. 221 absolute gravimeter. In June 2007 and in the years 2008 and 2011 such gravimetric measurements were performed by the team from Department of Geodesy and Astronomical Geodesy of Warsaw University of Technology using FG5 No. 230 absolute gravimeter. Elaboration of observation sessions from both gravimeters was performed in the Department of Higher Geodesy following the procedures used in constituting of uniform gravimetric system of geodynamic polygons reference. This constituting of gravimetric system comprised inter alia application of identical models of lithospheric tides (global model by Wenzel, 1997) and ocean tides (Schwiderski, 1980) (reduction of absolute measurements with tidal signals). Observations performed during summer of 2007, autumn of 2007, and spring of 2008 and 2011 indicated existence of small changes of absolute gravity of the order of 1 Gal. Maxima of accelerations appear in the spring period, and minima in the autumn period. This effect is connected with the influence of global hydrological factors the annual amplitude of which is ca 1,5 Gal and achieve extreme values in the spring-autumn interval. Very small value of observed amplitude of gravity changes in the period of extreme variability suggests that the observed gravity changes in LG are caused only by global phenomenon. This proves high degree of „independence” of gravimetric measurement base in LG from the local environmental factors such as ground water level variations, ground humidity, impact of snow cover, etc. At this moment the instrumental environment of absolute measurements obtains particular value, especially in the case of the tiltmeters and relative the gravimeter Lacoste&Romberg (LR-648). The relative gravity measurements as performed simultaneously with absolute gravity measurements enable us to determine the local tidal ephemeredes which makes it possible to replace the global tidal modal with ocean tidal model with the more realistic, locally determined tidal parameters (the local tidal ephemeredes).
3
Content available An automation gravity measurements with using PDA computers
Pachuta A., Dragan G., Olszak T.
Reports on Geodesy
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2011
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z. 1/90
355--360
EN
Preliminary processing of relative g measurements, including height, tidal, drift corrections and error analysis, was possible inthe field by use of GRAW22 software. Program has been developed at the Warsaw University of Technology in nineties of previous century in OPL language to PSION microcomputer (Pachuta at all, 2001). Newer field computers, enabled more computational power and modern programming languages, allowing wider programming possibilities. New software to field operations connected with relative gravity measurements has been developed on WindowsCE platform – by GRAVANALYSER. Software can be used on different palmtops and supports every steps connected with gravimeter reading, computation of corrections and strategy of processing. In this paper short description of such software is presented. Differences between selected strategies of drift and tidal corrections computation are also presented.
4
Content available Unified gravimetric reference frame for Polish IGS/EPN stations and geodynamic test fields
Walo J., Olszak T., Pachuta A., Próchniewicz D., Szpunar R.
Reports on Geodesy
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2010
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z. 1/88
105-113
5
Content available Surveing with the A10-020 absolute gravimeter for geodesy and geodynamics - First results
Kryński J., Sękowski M.
Reports on Geodesy
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2010
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z. 1/88
27-35
EN
The A10 is the first outdoor absolute gravimeter that allows to determine gravity with high precision. Absolute gravity survey with the A10 becomes highly competitive in terms of both efficiency and precision with traditional relative gravity survey. The portable A10-020 absolute gravimeter has been installed at the Borowa Gora Geodetic-Geophysical Observatory is September 2008. Since then a number of test measurements was conducted. Under laboratory conditions the series of gravity determination was obtained at two independent pillars at Borowa Gora as well as in Metsahovi and the BIPM gravimetric laboratories. Also a number outdoor gravity measurements with the use of mobile gravimetric laboratory was performed at the stations of gravity control in Poland and in Finland. The results obtained indicate higha quality of gravity determination with the A10under laboratory conditions and unprecedented quality under field conditions. They confirm the applicability of the A10 absolute gravimeter to the modernization of gravity control and high precision gravity survey required in modern gravity networks, but also usefulness in microgravimetry as well as geodynamics. Some practical problems concerning the use of the A10 and its operational procedure are discussed.
6
Content available Modelling of hydrological mass variation on the site Modra-Piesok
Mojzes M., Mikolaj M.
Reports on Geodesy
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2010
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z. 1/88
21-25
7
Content available Investingation in tidal gravity results in Józefosław Observatory
Rajner M.
Reports on Geodesy
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2010
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z. 1/88
7-14
EN
In this paper we used 40 months (2007-2010) of continuous gravity measurements to study different tidal phenomena. The records are taken from the Observatory in Józefosław equipped with LaCoste&RombergEarth Tide Gravimeter. Tidal gravity parameters in diurnal and semi-diurnal bands are computed using international standard data processing techniques. Accuracy assessment, as well variation in time of those parameters are given. Long series of consistent data allow to investigate in small signals such as gravity changes due to ocean loading. Subtracting body tides from results yields a differences up 1 uGal which are in good agreement with computed indirect ocean effect using most recent models. It clearly explains main source of disagreement between results from measurements and tidal models, despite of long distance to mearest ocean. Paper deals also with barometric pressure influence on gravity measurements. Importance of reducing pressure variation in tidal analysis is discussed and admittance factor is computed.
8
Content available Calibration of spring gravimeter using absolute gravity Measurements
Rajner M., Olszak T.
Reports on Geodesy
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2010
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z. 1/88
15-20
EN
Comparison of gravimeters relative to absolute measurements is frequently used method for determination of gravimeters scale factor. This technique as completely non-invasive is especially important in periodic control of continuously recording gravimetres. We used 30 repeated parallel observation of LaCoste&Romberg spring gravimeter with FG5 ballistic gravimeter in Józefosław Observatory carried out in last 40 months. Long series of repeated measurements allow us for comprehensive study on utility of calibration with this procedure. Different computational approaches was performed. Temporary variation of LCR scale factor with accuracy assessment aer comsidered. Discussion concerning reliability of calibration dependent on measurements length was also given.
9
Content available remote Ocean tidal loading from the gravity measurements at Józefosław Observatory
Rajner M.
Artificial Satellites : Journal of Planetary Geodesy
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2010
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Vol. 45, No. 4
175--183
EN
Ocean tidal loading is important source of disturbances in precise gravity measurements. Nowadays gravimeters reached unprecedented relative accuracy and loading signal can be observed also at large distances from the oceans. In this paper theoretical calculations are compared with analysis made on the basis of observations collected in Józefosław Observatory during last three years with use of LCR-ET spring gravimeter. Long series of consisted data allowed for investigation in small subtle gravity signals. Subtracting body tides from tidal analysis results yields discrepancies of a few nm/s2 for main tidal constituents which are in good agreement with computed ocean loading using most recent ocean models.
10
Content available Jednolity system grawimetrycznego odniesienia polskich stacji permanentnych GNSS i poligonów geodynamicznych - część dolnośląska
Olszak T., Pachuta A., Próchniewicz D., Szpunar R., Trojanowicz M., Walo J.
Acta Scientiarum Polonorum. Geodesia et Descriptio Terrarum
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2008
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Vol. 7, nr 4
45-66
PL
W latach 2006–2007 założono na obszarze Polski sieć punktów bezwzględnych pomiarów grawimetrycznych stanowiącą system grawimetrycznego odniesienia polskich stacji permanentnych GNSS i poligonów geodynamicznych. Dolnośląska część tego systemu składa się z pięciu punktów położonych w miejscowościach: Wrocław, Kłodzko, Janowice Wielkie, Lubiąż i Świebodzice. W niniejszej pracy szczegółowo omówiono położenie punktów Wrocław, Kłodzko, Janowice i Lubiąż, sposób ich stabilizacji oraz wyniki pierwszych pomiarów zrealizowanych na tych punktach.
EN
In years 2006–2007, at the area of Poland there were established a network of the absolute gravity measurements points for definition gravity reference system of the Polish Permanent GNSS network and geodynamic networks. Lower Silesian part of the system consist of five points situated in places: Wroc"aw, K"odzko, Janowice Wielkie, Lubi#$ i &wiebodzice. The paper contain detailed description of location of the points Wroc"aw, K"odzko, Janowice and Lubi#$, methods of monumentation and first results of measurements made at the points.
11
Content available remote New measurements for the determination of local vertical gradients
Csapó G., Völgyesi L.
Reports on Geodesy
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2004
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nr 2/69
303--308
EN
Measured vertical gravity gradients usually quite differ from the normal value of 0.3086 mGal/m (1mGal = 10-5/s2). Generally the changing of vertical gradient is rather big, up to a few 10 cm height above the ground and can be taken into consideration as a second order function. Over 40 m height the changing is linear and over 500 m height the changing is very small, the measured value of vertical gradient is about 0.3073 mGal/m. At present the datum level (mGal level) of modern gravity networks are mostly determined by absolute gravity values measured by absolute gravimeters, which values are referred to the reference heights of absolute gravimeters. So the datum level (mGal level) of the network of absolute points differs from the datum level of the network of relative measurements. The vertical gradients can be used for the conversion of measured gravity from the reference height of an instrument to a bench mark. So the vertical gradients are playing a key role for joining the two types of network. The height correction is necessary to determine by an accuracy of several fiGal, not to decrease the reliability of the transformed value of gravity. So the vertical gradients should be determined as high accuracy as it possible and using the normal value of vertical gradient (0.3086 mGal/m) is not sufficient for this purpose.
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