Romuald Obuchovski

Lietuvos gravimetrinio tinklo charakteristikos

Santrauka Lietuvos teritorijos gravimetrini pagrinda sudaro trys absoliuciuju matavimu punktai bei pirmosios klases gravimetrinis tinklas, jungiantis 48 punktus. Detalesniems Lietuvos teritorijos geopotencialinio lauko tyrimams atlikti sudarytas 635 punktu antrosios klases gravimetrinis tinklas. Tinklas matuotas keturiais gravimet‐rais Scintrex CG‐5. Matavimu rezultatai apdoroti (GRAVSOFT programu paketo procedūros). Pateikiami gravimetrinio tinklo tikslumo ivertinimo duomenys.

An Investigation of the Automatic Relative Gravimeters

The laboratory and field investigations of the several automatic gravimeters Scintrex CG_5 with a quartz elastic system used for the determining of gravity acceleration were performed. Research on characteristics of four gravimeters includes a five-year period. The data consists of gravimetric observations at a laboratory, on the gravimetric testline and at the points of the Lithuanian gravimetric network. The evaluation of the phenomena of the spring systems of the gravimeters was made. The stress on the estimation of the zero drift at a laboratory and field investigations was done. It was detected that zero drift does not exceed 500 μGal per day with a diapason of 200 μGal. The zero drifts per hour do not exceed 25 μGal, mostly they are under 10 μGal. According to the annual calibration results the character of the changes of the linear scale coefficients of the gravimeters were analysed too. The calibration base of 270 km length in Lithuania where the difference of the gravity acceleration of the end points is 201 mGal was used for investigations. The research showed that the biggest deviation from the unit of the linear scale coefficients does not exceed 0.013. It was noted, that the values of the linear scale coefficients of the gravimeters have a tendency to decrease. Also was noted, that the values of the linear scale coefficients have a tendency to decrease in the period between field works, and to increase - in the field works period. So the calibration of the gravimeters should be carried out before and after the field works. Based on measurements carried out during development of the Lithuanian gravimetric network, which consists of 686 gravimetric points, accuracy of gravity acceleration increments was assessed. The comparison of the observations results against the results, obtained by the LaCoste and Romberg gravimeters with metal elastic system, is presented too. The total number of common points is 51. It was stated, that the differences of the gravity accelerations measured by the different types of gravimeters at gravimetric points do not differ more than 10 μGal, therefore maximum difference of 25 μGal was received. The standard deviations of the gravity accelerations of the gravimetric points do not exceed 7 μGal. Such results show the good performance of the SCINTREX CG_5 gravimeters.

Some issues regarding the calibration of the terrestrial laser scanner Leica Scanstation C10

AbstractSome issues regarding the calibration results pertaining to the ground-based laser scanner Leica Scanstation C10 are presented and analysed. The calibration was carried out at Kyviskės Calibration Baseline (Jokela et al. 2002) and the special cyclic error detection baseline at the Research Institute of Geodesy of Vilnius Gediminas Technical University. The instrument was calibrated at 20, 100, 180, 200 and 260 m distances at Kyviskės Calibration Baseline and the indoors baseline from 1 to 15 m with continuous 1 m interval. The special procedure of indirect measurements was suggested to estimate errors of scanner measurements. During this procedure, the positions of the scanstation varied from the calibration baseline pillars to the standard tripods creating triangles of different shapes. The distances obtained by scanning targets placed on the calibration baseline pillars were compared with baseline standard distances. Suggested improvements in the calibration technology could be used for verifica...

MATAVIMŲ SCINTREX CG-5 GRAVIMETRAIS ANALIZĖ

Santrauka Atlikti keturių Scintrex CG-5 gravimetrų tyrimai. Remiantis gravimetrinės bazės, įrengtos Lietuvos teritorijoje, matavimų duomenimis, nustatyta gravimetrų kalibravimo koeficientai ir jų kitimo pobūdis. Atlikti sunkio pagreicio vertikaliojo gradiento astuonių aukstų pastate tyrimai. Laboratorinėmis sąlygomis nustatytas gravimetrų paros nulio slinkties kitimo diapazonas. Atlikti gravimetrų nulio slinkties matavimų metu tyrimai.

Measurement Techniques of a European Sea Level Service Site in KLAIPEDA

The technical equipment including hardware and software of European Sea Level Service (ESEAS) station KLAIPEDA (KLPD) is presented in the paper. The tide gauge Klaipeda (previous name – Memel) was established in 1811 in the east part of the Baltic Sea, at the estuaries of Curonian Lagoon. KLAIPEDA ID number at the Permanent Service of Mean Sea Level (PSMSL) is 080161. Upgrading of the station is done according to the ESEAS-RI project (Contract No EVR1-CT-2002-40025). KLPD site was equipped with a digital float tide gauge, sea-water conductivity sensor, air temperature, pressure and humidity sensors, wind speed and direction sensor and GPS receiver with antenna. The four characters ID KLPD and IERS DOMES number 10802M001 was assigned to the permanent GPS station KLAIPEDA. Tide gauge KLAIPEDA was certified as ESEAS Operational Site in 2003. It provides near real time (hourly) data to corresponding data servers. The data warehouse system is built on Gentoo Linux, with Apache2, MySQL 4.0.22 and PHP 4.3.9. The communication structure and software applications are also presented in the paper.

WMM‐00 Geomagnetinio lauko modelio lietuvos teritorijoje tikslumo tyrimas

Santrauka Matavimu technikos lygis teikia galimybe detaliau istirti Žemes pavirsiuje vykstancius fizikinius procesus. Atliekant geomagnetinio lauko palydovinius stebejimus, tikslius ir nuolatinius matavimus magnetinese observatorijose, geomagnetinius lauko matavimus amžiu variaciju punktuose, aeromagnetinius ir jūru matavimus sukaupta nemažai informacijos apie geomagnetinio lauko issidestyma erdveje ir jo kitima laike. Tokios informacijos gausybe suteikia galimybe matematiskai modeliuoti geomagnetini lauka. Geomagnetinio lauko modeliai placiai taikomi oro navigacijos, karybos bei civiliniams tikslams. Straipsnyje ivertintas WMM‐00 (World Magnetic Model) geomagnetinio lauko modelio tikslumas Lietuvos teritorijoje. Pagal si modeli nustatomos topografiniu 1:50 000 mastelio žemelapiu magnetines deklinacijos reiksmes. Sio modelio duomenys taip pat naudojami aviacijoje skaiciuojant aerouosto irenginiu magnetinio azimuto ir magnetines deklinacijos reiksmes.

Gravimetriniu tinklu išlyginimas, taikant skirtingus išlyginimo modelius

Santrauka Analizuojama gravimetriniu tinklu islyginimas, taikant papildomus parametrus ir salygines lygtis, kolokacijos metoda, bei islyginant laisvo tinklo pavidalu. Taikant papildomus parametrus ir salygines lygtis gravimetriniu tinklu islyginimo procedūrose galima analizuoti matavimu sistemingasias klaidas, pavyzdžiui, gravimetru nulio slinkti. Kadangi tokiai analizei atlikti naudojama tam tikra matavimu informacijos dalis, del sios operacijos sumažeja islygintu pagrindiniu parametru tikslumas. Gautos formules isreiskia gravimetrinio tinklo islygintuju pagrindiniu parametru kovariaciju matricu pokycius tais atvejais, kai netaikomi ir kai taikomi papildomi parametrai. Is kovariaciju matricos diagonaliuju elementu didumo matyti, kaip pakinta islygintuju pagrindiniu parametru dispersijos, islyginimo procedūrose taikant papildomus parametrus. Tokia islyginimo procedūra tikslinga atliekant issamesne gravimetriniu tinklu analize, vertinant galimu klaidu saltinius.

Analysis of earth's magnetic field changes by correlation of its parameters

Abstract Changes of Earth magnetic field parameters: field intensity and its components along axes of rectangular coordinates are analyzed in space and time. Data from magnetic observatories Belsk and Hel in Poland were used. Correlation analysis of magnetic field components was applied. Influence of respective field components on changes of geomagnetic field intensity was determined. Shift of space and time factors was used to assess the influence of covariations of geomagnetic field components on changes of covariations of field intensity.

Research on magnetic declination in Lithuanian territory

Abstract Magnetic declination is the angle between the planes of the astronomic and magnetic meridians. Magnetic declination is used in navigation, geophysics, geodesy, cartography, geology, and other fields. Magnetic declination is often computed from the World Magnetic Model (WMM). It is therefore important to be aware of the accuracy of the computed declination and to investigate its changes. For this purpose, magnetic declination was measured and the methodology of its measurement analyzed. Research was performed at six established points in 1999, 2001 and 2004. Magnetic declination was measured at Vilnius, Kaunas and Klaipeda airports in 2006.