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12. Coherence between geophysical excitations and celestial pole offsets

Creator:
Cyril Ron and Jan Vondrák
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, geofyzika, geophysics, geophysical excitations, celestial pole offsets, coherence, 7, and 551
Language:
English
Description:
Celestial pole offsets are the displacements between the observed position of the Earth’s spin axis in space and its position predicted by the adopted models of precession and nutation. At present, the models are IAU2006 and IAU 2000, respectively. The celestial pole offsets are regularly measured by Very Long-Baseline Interferometry (VLBI), the observations being coordinated and published by the International VLBI Service for Geodesy and Astrometry (IVS). These offsets contain a mixture of several effects: the unpredictable free term, Free Core Nutation (FCN) that is due to the presence of the outer fluid core of the Earth, forced motions excited by the motions in the atmosphere and oceans, and also imperfections of the adopted precession-nutation models. The geophysical excitations are also available, as determined by several atmospheric and oceanographic services. The aim of this paper is to compare the time series of these integrated excitations with the observed celestial pole offsets and estimate the level of coherence between them., Cyril Ron and Jan Vondrák., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

13. Determination of intermediate orbit and position of glonass satellites based on the generalized problem of two fixed centers

Creator:
Władysław Góral and Skorupa, Bogdan
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, geofyzika, geophysics, GLONASS, orbit determination, problem of two fixed centers, 7, and 551
Language:
English
Description:
The mathematical model and algorithms for calculating the position of GLONASS satellites by means of their broadcast ephemeris is presented in the paper. The algorithms are based on the generalized problem of two fixed centers. One of the advantages of the analytical solution obtained from the generalized problem of two fixed centers is the fact that it embraces perturbations of all orders, from the second and also part ly from the third zonal harmonics (Aksenov, 1969). GLONASS broadcast ephemeris - provided every 30 minutes - contain satellite position and velocities in the Earth fixed coordinate system PZ-90.02 (ICD, 2008), and acceleration due to luni-solar attraction. The GLONASS Interface Control Document recommends that a fourth order Runge-Kutta integration algorithm shall be applied. In the Department of Geomatics (AGH UST) a computer program has been established for fitting position and velocity of GLONASS satellites using their broadcast ephemeris. Intermediate GLONASS satellite orbits are calculated consider ing also the second and third zonal harmonics in the gravitational potential of the Earth. In this paper results of the analytical integration of the equation of the motion of the GLONASS satellites compared to the numerical solution are provided., Władysław Góral and Bogdan Skorupa., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

14. Determination of near-surface apparent resistivity by means of high frequency mutual impedance measurements

Creator:
Beziuk, Grzegorz and Mydlikowski, Remigiusz
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, geofyzika, geophysics, geophysical method, loop antennas, mutual impedance, apparent resistivity, 7, and 551
Language:
English
Description:
A method of determination the apparent resistyvity of the ground’s near-surface la yers from measurements of the mutual impedance of a loop antenna system operating at a high frequency is presented. An analysis of the sensitivity of mutual impedance to variation in the parameters of conducting half space at different frequencies had been carried out. Additionally influence of displacement current on measured mutual impedance values was discussed. A frequency of measuring system was selected in order to obtain a high sensitivity of the measuring system to detection inhomogeneities characterised by small dimensions and low apparent resistyvity contrast. The measuring system and the method of interpreting measurement results were described. The results of field measurements were presented., Grzegorz Beziuk and Remigiusz Mydlikowski., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

15. Determination of the horizontal deformation factor for mineral and fluidized deposits exploitation

Creator:
Sroka, Anton, Misa, Rafał, and Tajdus, Krzysztof
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
geodynamika, geomechanika, geofyzika, geologie, těžba nerostných surovin, geodynamics, geomechanics, geophysics, geology, horizontal deformation, horizontal displacement, mining operation, Avershin’s hypothesis, 7, and 551
Language:
English
Description:
In this article, the authors use the existing theoretical foundations and partial solutions to provide a general formula, which can be used to determine the value of horizontal deformation factor B for various applications of the Knothe theory. This applies to the calculation of surface deformation not only in the case of hard coal mining, but also in the case of salt mining by borehole. Convergence resulted from mining may cause deformations of caverns used to store liquid and gaseous fuels or the deformations related to the fluidized bed extraction. The calculations for the new analytical model are presented in the examples of the Etzel cavern (Germany) and the Upper Silesian Coal Basin (Poland). and Sroka Anton, Misa Rafał, Tajdus Krzysztof.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

16. Elektrická vodivost zemské kůry

Creator:
Pek, Josef
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
geofyzika, zemská kůra, elektrická vodivost, geophysics, earth crust, electric conductivity, 6, and 53
Language:
Czech
Description:
Elektrická vodivost v zemské kůře závisí jen málo na konkrétním horninovém složení geologických útvarů, často však velmi citlivě indikuje zóny s anomálními geochemickými a termodynamickými podmínkami či zóny mechanického porušení horninového prostředí. Elektromagnetická pole indukovaná přirozenými variacemi zemského magnetického pole extraterestrického původu a měřená na povrchu Země umožňují vymezit tyto anomální zóny v měřítku celé zemské kůry, a rovněž hlouběji v zemském plášti. Magnetotelurický a magnetovariační výzkum, který z těchto poznatků vychází, se tak stává cenným zdrojem geofyzikální informace o vnitrozemském prostředí. Elektrický model zemské kůry na přechodu mezi Českým masivem a Západními Karpatami zřetelně ukazuje, jak povrchová geologická stavba pokračuje v hlubinných změnách v rozložení elektrické vodivosti v rámci jednotlivých regionálních geologických jednotek., Josef Pek., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

17. Elektromagnetická indukce v Zemi: pohled z oběžné dráhy

Creator:
Velímský, Jakub, Martinec, Zdeněk, and Everett, Mark E.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
geofyzika, elektromagnetismus, umělé družice, geophysics, electromagnetism, artificial satellites, 6, and 53
Language:
Czech
Description:
Příspěvek se zabývá modelováním elektromagnetické indukce v nehomogenní Zemi za použití observatorních a satelitních dat. Současný nárůst výkonu výpočetní techniky a dostupnost geomagnetických měření ze satelitů na nízkých oběžných drahách otevírají této tradiční geofyzikální metodě zkoumání zemského nitra nové možnosti. V první části článku je studován vliv vodivostních nehomogenit v litosféře na pozorování satelitů Ǿrsted a CHAMP během klidných dní v letech 2001-2002. Ukazuje se, že trojrozměrný model, který zahrnuje vysoký vodivostní kontrast mezi oceány a kontinenty, vystihuje satelitní data o 10-15 % lépe než nejlepší sféricky symetrický model. Ve druhé části článku modelujeme EM indukci excitovanou geomagnetickými bouřemi v komplikovaném trojrozměrném modelu pláště, odvozeném z laboratorních měření vodivosti a ze seismické tomografie. Provedené simulace poukazují na význam laterálně nehomogenní vodivosti ve středním plášti. Anomálie ve výškách typických pro nízko letící satelity predikujeme ve velikosti jednotek nT. Tyto hodnoty jsou v souladu s výsledky nedávné analýzy dat ze satelitu Magsat., Jakub Velímský, Zdeněk Martinec, Mark E. Everett., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

18. Estimates of seasonal signals in GNSS time series and environmental loading models with iterative least-squares estimation (ILSE) approach

Creator:
Kaczmarek, Adrian and Kontny, Bernard
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
geodynamika, geomechanika, geofyzika, geologie, geodynamics, geomechanics, geophysics, geology, wavelet analysis, seasonal signal, coordinates time series, loading models, phase shift, cross-correlation, correlation coefficient, 7, and 551
Language:
English
Description:
The GNSS (Global Navigation Satellite System) coordinates time series are still used as a source for determining the velocities of GNSS permanent stations. These coordinates, apart from the geodynamical signals, also contain an interference signal. This paper shows the results of the comparative analysis of the GNSS coordinates time series with a deformation of the Earth's crust obtained from loading models. In the analysis, coordinates time series are used (CODE Repro2013) without loading models (Atmospheric Pressure Loading, Hydrology, Non-Tidal Ocean Loading) at the stage of the reprocessing of GNSS archival data. The analyses showed that in the case of the Up component there is a high correlation between the GNSS coordinates changes and deformations of the Earth's crust from the loading models (coefficient 0.5-0.8). Additionally, we noticed that for horizontal components (North, East) changes occur in the phase shift between coordinates, and the Earth’s crust deformations signals are accelerated or delayed each other (-150 to 200 days). This article shows new methods of iLSE (iteration Least Square Estimation) to determine periodic signals in the time series. Additionally, we compared the values of estimated amplitudes for GNSS and deformation time series. and Kaczmarek Adrian, Kontny Bernard.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

19. Evaluation of long-term BeiDou/GPS observation quality based on G-Nut/Anubis and initial results

Creator:
Zhao, Lewen, Jan Douša, Václavovič, Pavel, Ye, Shirong, and Xia, Fengyu
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
geodynamika, geomechanika, geofyzika, geologie, otevřený software, jakost, geodynamics, geomechanics, geophysics, geology, open source software, pozorování, G-Nut/Anubis, pre-processing, BeiDou, observation quality, open source, 7, and 551
Language:
English
Description:
Reliable observations are the prerequisite for high-precision GNSS data processing. Data quality evaluation at the pre-processing procedure can help the user to identify the weakness of the observations. The open source software package G-Nut/Anubis developed at Geodetic Observatory Pecny (GOP) is introduced and used for the evaluation of long-term BeiDou/GPS signal. Several key indicators are selected to evaluate the BeiDou/GPS observations. Quantitative analysis shows that more than 100 stations can achieve 6-hour standalone BeiDou positioning at least. The completeness of the BeiDou phase and code observations at three frequencies is higher than that of the GPS observations in the selected station which is mainly attributed to the high elevation observations from GEO and IGSO satellites. Qualitative analysis shows that the multipath effects for pseudorange observations are correlated with signal, receiver types and firmware versions besides the station environment. Users attempting to improve the pseudorange observations by multipath filter should pay attention also to the receiver-specific settings. Cycle slip counts are used to indicate the quality of carrier-phase observations. Results show that BeiDou C05 satellite is more affected by the cycle slips, in particular the third frequency observables. For GPS, the third frequency is more robust compared to the legacy frequencies. Comprehensive single point positioning results show that positioning accuracy for BeiDou is worse than that of GPS, which is mainly caused by less active satellites, worse geometry and the larger errors in the broadcast ephemeris. The BeiDou positioning accuracy was further degraded by the C13/C15 satellite and dominated by large clock errors. Broadcast evaluation shows that the BeiDou orbit errors are related to the constellations. Overall, the orbit precision for both GPS and BeiDou has been gradually improved. Outliers were observed for navigation records assigned with the healthy status, especially for BeiDou broadcast orbits. and Zhao Lewen, Dousa Jan, Vaclavovic Pavel, Ye Shirong, Xia Fengyu.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

20. Extreme solar activity of early February 1986 and its geophysical consequences

Creator:
Marková, E., Pastorek, L., Zloch, F., Laštovička, J., Perglerová, P., and Pýcha, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
geophysics, flares, and extreme solar activity
Language:
Czech
Description:
During the solar cycle minimum period, a period of a suddenly enhanced solar activity occurred in early February 198d. Two proton flares were observed during this period after a long period of a totally quiet solar activity (R = 0 on most days in the second half of December and in January). Other flares, various phenomena accompanying proton flares, like type II and type IV radio bursts and a large Forbush deerease of cosmic ray intensity were observed as well as an extremely severe geomagnotic storm (Kp = 9) and strong disturbances in the Earth´s ionosphere (SIDs and ionospheric storm), Czechoslovak solar and geophysical observations for this period are presented and interpreted with the use of other observations. Special attention is given to the flares of February 4 (start 0732 and 1025 UT) and February 5 (start 0934 UT) because spectrohelioscopic observations from the Hurbanovo observatory are available for these events.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public