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1

Expanding seismic surface waves measurements towards low periods with gravity measurements

Wilde-Piórko M., Dykowski P., Polkowski M., Olszak T., Grad M., Kryński J., Sękowski M., Krankowski A., Rajner M.

Geoinformation Issues

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2017

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Vol. 9, no. 1(9)

5--13

EN

Seismic events in gravity measurements are considered as disturbances and are usually removed from the records. However, the physical properties of tidal gravimetric instruments allow researchers to record seismic surface waves of very long periods. In the case of a superconducting gravimeter, periods of even up to 400 s can be determined. Simultaneous seismic and gravity records at the same locations allow the study of a wider response for incoming seismic waves by using two quite different instruments. For test purposes 4 seismometer-gravimeter pairs were temporarily deployed in Poland at three locations: Borowa Gora Geodetic-Geophysical Observatory (BG), Jozefoslaw Astro-Geodetic Observatory (JO), and Lamkowko Satellite Observatory (LA). During the test period from December 2016 to May 2017 several large teleseismic events were observed with well-formed surface waves. Group velocity dispersion curves for long surface waves, as well as periods of free oscillations are presented for selected events. The correlation of a broadband seismometer signal with different types of gravimetric sensors signals gives the opportunity to analyse gravimeter noise components, in the instrumental and micro-seismic domains.

PL

Zjawiska sejsmiczne w pomiarach grawimetrycznych są traktowane jako zakłócenia i zwykle ich efekty są usuwane z zapisów grawimetrycznych. Jednakże, grawimetry dzięki swojej konstrukcji umożliwiają rejestrację sejsmicznych fal powierzchniowych o bardzo długich okresach. W przypadku grawimetru nadprzewodnikowego, możliwe jest zaobserwowanie fal powierzchniowych, generowanych przez trzęsienia ziemi, o okresach nawet do 400 s. Przeprowadzenie równoczesnych rejestracji sejsmicznych i grawimetrycznych instrumentami zlokalizowanymi w tym samym miejscu, powinno umożliwić przeanalizowanie szerszego zakresu częstości sygnału sejsmicznego niż w przypadku użycia tylko jednego typu instrumentu. W celu sprawdzenia prawdziwości powyższego stwierdzenia, 4 pary instrumentów: sejsmometrów i grawimetrów zostały zainstalowane w Polsce w trzech lokalizacjach, w Obserwatorium Geodezyjno-Geofizycznym Borowa Góra (BG), Obserwatorium Astronomiczno-Geodezyjnym Józefosław (JO) oraz Obserwatorium Satelitarnym Lamkówko (LA). W czasie projektu pilotażowego, trwającego od grudnia 2016 do maja 2017 roku, zarejestrowano kilka dużych trzęsień ziemi z dobrze wykształconymi falami powierzchniowymi. W pracy zaprezentowano krzywe dyspersji grupowych prędkości fal powierzchniowych, jak również okresy oscylacji swobodnych dla wybranych zjawisk. Korelacja szerokopasmowego sygnału sejsmicznego z sygnałem zarejestrowanym przez różnego typu grawimetry umożliwi analizę szumu grawimetrycznego w zakresie częstości pływowych instrumentów, jak i w zakresie mikrosejsmicznym.

2

Sibsonian and non-Sibsonian natural neighbour interpolation of the total electron content value

Kotulak K., Froń A., Krankowski A., Pulido G. O., Henrandez-Pajares M.

Acta Geophysica

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2017

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Vol. 65, no. 1

13--28

EN

In radioastronomy the interferometric measurement between radiotelescopes located relatively close to each other helps removing ionospheric effects. Unfortunately, in case of networks such as LOw Frequency ARray (LOFAR), due to long baselines (currently up to 1500 km), interferometric methods fail to provide sufficiently accurate ionosphere delay corrections. Practically it means that systems such as LOFAR need external ionosphere information, coming from Global or Regional Ionospheric Maps (GIMs or RIMs, respectively). Thanks to the technology based on Global Navigation Satellite Systems (GNSS), the scientific community is provided with ionosphere sounding virtually worldwide. In this paper we compare several interpolation methods for RIMs computation based on scattered Vertical Total Electron Content measurements located on one thin ionospheric layer (Ionospheric Pierce Points—IPPs). The results of this work show that methods that take into account the topology of the data distribution (e.g., natural neighbour interpolation) perform better than those based on geometric computation only (e.g., distance-weighted methods).

3

Prospects for Solar and Space Weather Research with Polish Part of the LOFAR Telescope

Dąbrowski B. P., Krankowski A., Błaszkiewicz L., Rothkaehl H.

Acta Geophysica

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2016

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Vol. 64, no. 3

825--840

EN

The LOw-Frequency ARray (LOFAR) is a new radio interferometer that consists of an array of stations. Each of them is a phase array of dipole antennas. LOFAR stations are distributed mostly in the Netherlands, but also throughout Europe. In the article we discuss the possibility of using this instrument for solar and space weather studies, as well as ionosphere investigations. We are expecting that in the near future the LOFAR telescope will bring some interesting observations and discoveries in these fields. It will also help to observe solar active events that have a direct influence on the near-Earth space weather.

4

Prospects for Scrutiny of Pulsars with Polish Part of LOFAR

Błaszkiewicz L., Lewandowski W., Krankowski A., Kijak J., Koralewska O., Dąbrowski B. P.

Acta Geophysica

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2016

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Vol. 64, no. 1

293--315

EN

LOFAR (LOw Frequency ARray) is a new generation digitally controlled radio telescope consisting of phased array antenna stations with sensitivity, bandwidth, range of frequency, and digital processing power that makes it an excellent tool for observations of pulsars. This interferometric instrument is able to work in a single-station mode as well as in group-of-selected-stations mode. This article discusses the great opportunity for conducting unique and independent research of pulsar sources with the three LOFAR stations located in Poland and maintained by the POLFAR consortium.

5

Results of the application of tropospheric corrections from different troposphere models for precise GPS rapid static positioning

Wielgosz P., Paziewski J., Krankowski A., Kroszczyński K., Figurski M.

Acta Geophysica

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2012

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Vol. 60, no. 4

1236-1257

EN

In many surveying applications, determination of accurate heights is of significant interest. The delay caused by the neutral atmosphere is one of the main factors limiting the accuracy of GPS positioning and affecting mainly the height coordinate component rather than horizontal ones. Estimation of the zenith total delay is a commonly used technique for accounting for the tropospheric delay in static positioning. However, in the rapid static positioning mode the estimation of the zenith total delay may fail, since for its reliable estimation longer observing sessions are required. In this paper, several troposphere modeling techniques were applied and tested with three processing scenarios: a single baseline solution with various height differences and a multi-baseline solution. In specific, we introduced external zenith total delays obtained from Modified Hopfield troposphere model with standard atmosphere parameters, UNB3m model, COAMPS numerical weather prediction model and zenith total delays interpolated from a reference network solution. The best results were obtained when tropospheric delays derived from the reference network were applied.

6

"ASG+": Project for improving Polish Multifunctional Precise Satellite Positioning System

Figurski M., Bogusz J., Bosy J., Kontny B., Krankowski A., Wielgosz P.

Reports on Geodesy

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2011

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z. 2/91

51-57

7

Application of predictive regional ionosphere model to medium range RTK positioning

Wielgosz P., Krankowski A., Sieradzki R., Grejner-Brzezińska D.

Acta Geophysica

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2008

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Vol. 56, no. 4

1147-1161

EN

Real Time Kinematic (RTK) GPS positioning over longer distances requires a support of atmospheric (ionospheric and tropospheric) corrections, since the atmospheric errors decorrelate with the growing distances and cannot be completely eliminated by double differencing of the satellite observations. Currently, the most commonly used approach is to derive the atmospheric corrections at the reference station network and provide them in real time to the roving receiver. Another solution, proposed here, is to use predictive atmospheric models in order to derive the atmospheric corrections. This paper presents the test results of the performance assessment of the predictive ionosphere model (UWM-IPM) application to medium-range RTK positioning. The rover data collected within 25 to 67 km from the closest reference station were processed in the kinematic mode with the support of the ionospheric corrections derived from the UWM-IPM model. The RTK solution was derived in both single-and multi-baseline modes, and compared to the two reference solutions obtained without the ionospheric corrections. All numerical tests were carried out using the MPGPS software developed in cooperation with The Ohio State University; a recent extension to the software, developed at the University of Warmia and Mazury in Olsztyn, introduces the predictive ionosphere model to the RTK solution. The test results are very promising, and indicate that predicted ionosphere corrections can effectively support medium-range RTK positioning, and allow for fast ambiguity resolution over distances of several tens of kilometers under moderate ionospheric conditions.

8

The structure of the mid- and high-latitude ionosphere during the November 2004 storm event obtained from GPS observations

Krankowski A., Shagimuratov I.I., Baran L.W., Yakimova G.

Acta Geophysica

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2007

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Vol. 55, no. 4

490-508

EN

GPS data from the International GNSS Service (IGS) network were used to study the development of the severe geomagnetic storm of November 7-12, 2004, in the total electron content (TEC) on a global scale. The TEC maps were produced for analyzing the storm. For producing the maps over European and North American sectors, GPS measurements from more than 100 stations were used. The dense network of GPS stations provided TEC measurements with a high temporal and spatial resolution. To present the temporal and spatial variation of TEC during the storm, differential TEC maps relative to a quiet day (November 6, 2004) were created. The features of geomagnetic storm attributed to the complex development of ionospheric storm depend on latitude, longitude and local time. The positive, as well as negative effects were detected in TEC variations as a consequence of the evolution of the geomagnetic storm. The maximal effect was registered in the subauroral/auroral ionosphere during substorm activity in the evening and night period. The latitudinal profiles obtained from TEC maps for Europe gave rise to the storm-time dynamic of the ionospheric trough, which was detected on November 7 and 9 at latitudes below 50N. In the report, features of the response of TEC to the storm for European and North American sectors are analyzed.

9

Features of the ionosphere behavior before the Kythira 2006 earthquake

Zakharenkova I.E., Shagimuratov I.I., Krankowski A.

Acta Geophysica

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2007

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Vol. 55, no. 4

524-534

EN

In this paper we present specific features of TEC (total electron content of the ionosphere) behavior as possible precursors of Kythira (Southern Greece) earthquake of January 8, 2006 (M6.8). For this purpose, we used both the TEC data of GPS-IGS stations nearest to the epicenter, and TEC maps over Europe. The favorable circumstance for this analysis was the quiet geomagnetic situation during the period prior to the earthquake. One day before the earthquake, a characteristic anomaly was found out as the day-time significant increase of TEC at the nearest stations, up to the value of 50% relative to the background condition. To estimate the spatial dimensions of seismo-ionospheric anomaly, the differential mapping method was used. The ionosphere modification as a cloud-like increase of electron concentration situated in the immediate vicinity of the forthcoming earthquake epicenter has been revealed. The amplitude of modification reached the value of 50% relative to the non-disturbed condition and was in existence from 10:00 till 22:00 UT. The area of significant TEC enhancement had a size of about 4000 km in longitude and 1500 km in latitude.

10

Precise measurements of the changes of the ground water level in Lamkowko satellite observatory. Preliminary results

Krankowski A., Kaczorowski M., Baran L., Sieradzki R., Krypiak A.

Reports on Geodesy

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2006

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z. 2/77

47-52

EN

In the years 2003-2005 in the Lamkowko Satellite Observatory a measuring well equipped with a measuring float was establisshed. This measurement instrument was constructed jointly with Space Research Center of Polish Academy of Sciences. The measuring system enables to detect precisely changes in the level of ground water. The changes in the water level are measured with the accuracy better than 0.1 mm. the obtained accuracy of measuring allows to detect several phenomena: meteorological ones, geodynamics one4s, Earth tides. In this paper, the preliminary results of the first time series of changes of changes in the level of ground water are presented. The time series of these measurements, utilized in this study, cover only 4 months (from January to April 2006). Preliminary results enable to detect diurnal and semidiurnal oscillations.

11

Impact of tec fluctuations in the Antarctic ionosphere on GPS positioning

Krankowski A., Shagimuratov I. I.

Artificial Satellites : Journal of Planetary Geodesy

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2006

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Vol. 41, No. 1

43--56

EN

With increasing reliance on space-based platforms for global navigation and communication, concerns about the impact of ionospheric scintillation and total electron content fluctuations on these systems have became a high priority. In this paper, GPS transionospheric signals have been used to study the development of ionospheric phase fluctuations observed at Antarctic IGS permanent stations: McMurdo-MCM4, Casey-CAS1, Mawson-MAW1, Sanae-VESL, Syowa-SYOG and Davis-DAV1 in 2001. The use of the multi-station, multi-path observations of the GPS beacons has allowed the study of the time development of irregularities as a function of latitude and longitude of individual geomagnetic storms. The basic storms studied were those of March 19-20, March 31, April 9-11, June 16-17, and September 23, 2001. The rate of TEC (ROT) parameter was used to study the occurrence of TEC fluctuations. The results from studying these storms showed the unique nature of each storm. For the above five storms, data were available from three auroral stations (VESL, SYOG and MAW1) and from 61° to 70° Corrected Geomagnetic Latitude (CGL). In addition, data from three higher latitude polar stations (DAV1, MCM4 and CAS1) near 800 CGL are also analysed. Fluctuation effects, causing dramatic changes in total electron content – TEC, can have a different impact on GPS positioning accuracy (especially during phase ambiguity resolution). Bernese ver.4.2 software was used for the analysis of the GPS permanent data from Antarctic IGS stations. The analyses rely on studying the repeatability of vector co-ordinates. These vectors were investigated during the geomagnetic storms when the intensity of TEC fluctuations was more pronounced. The impact of TEC fluctuations in the high latitude ionosphere on GPS positioning accuracy has been discussed in terms of the total number of observations of doubledifferences (DD) and in the ratio of the total number of all ambiguities to unresolved ones.

12

Response of the ionosphere to the Baltic Sea earthquake of 21 September 2004

Krankowski A., Zakharenkova I., Shagimuratov I.

Acta Geophysica

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2006

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Vol. 54, no. 1

90-101

EN

GPS observations of the European permanent network were used to identify seismoionospheric precursors of Baltic Sea earthquake of 21 September 2004. It is a very rare event for this region of Europe (magnitude of about 5.0). This value is the threshold for the occurrence of seismic effects in the ionosphere. In total electron content (TEC) data over the region of the earthquake, a specific ionospheric anomaly appeared one day before the earthquake was detected. The ionospheric variability had a positive sign with an enhancement of about 4-5 TECU (1 TECU = 1016 electrons/m2) relative to the non-disturbed state of the ionosphere. The anomaly had a duration of 4-5 hours in the day time. The special size of this anomaly was about 1000 km. The characteristic parameters of the anomaly show that it can be associated with ionospheric precursors of an earthquake.

13

Analiza powtarzalności wyznaczeń współrzędnych i długości wektora Onsala-NyAlesund w okresie wzrastającej i maksymalnej aktywności słonecznej

Krankowski A., Sieradzki R.

Technical Sciences. Supplement / University of Warmia and Mazury in Olsztyn

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2005

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suppl. 2

61--68

PL

W pracy przedstawiono wyniki badań nad wykorzystaniem ciągłych obserwacji GPS ze stacji uczestniczących w międzynarodowym programie IGS (International GPS Service) do monitorowania wektorów w rejonie okołobiegunowym, których punkty są położone na różnych strukturach tektonicznych. Analizie poddano okres od 1996 r. (minimalna aktywność słoneczna) do 2001 r. (maksymalna aktywność słoneczna). Obserwacje opracowano za pomocą softwaru Bernese ver. 4.2. na podstawie całodobowych permanentnych obserwacji GPS. Prowadzone równolegle z monitorowaniem stanu jonosfery wyznaczenia dzień po dniu współrzędnych wektora łączącego stację Onsala (57,3°N, 11,9°E) z NyAlesund (78,9°N, 11,9°E) pozwoliły ujawnić wyraźną korelację między zmianami wartości TEC (Total Electron Content) występującymi w okresie spokojnej i zaburzonej jonosfery a zmianami wartości współrzędnych wektora o długości ponad 2300 km.

EN

The results of the analyses of IGS (International GPS Service) permanent observations to monitor GPS vectors, located at different tectonic platforms, in Arctic region are presented.GPS permanent observations Onsala (57,3°N, 11,9°E) and NyAlesund (78,9°N, 11,9°E) from 1996 (low solar activity) to 2001 (maximum solar activity) were analyzed. Software Bernese ver.4.2 was used for the analysis of the GPS observational data of 24-hour sessions. The ionspheric storms have considerable influence on the accuracy determination of the Onsala-Nyalesund vector coordinates. The results show exact dependence between TEC changes during quiet and disturbed ionospheric conditions and the repeatability of the vectors' coordinates and the length of the baselines, even for vectors longer than 2 300 km.

14

Study of TEC fluctuations in Antarctic ionosphere during storm using GPS observations

Krankowski A., Shagimuratov I.I., Baran L.W., Ephishov I.I.

Acta Geophysica Polonica

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2005

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Vol. 53, nr 2

205-218

EN

GPS observations carried out at Antarctic stations belonging to the IGS network were used to study TEC fluctuations in the high-latitude ionosphere during storms. Dual-frequency GPS phase measurements along individual satellite passes served as raw data. Ionospheric irregularities of a different scale develop in the auroral and polar ionosphere. This is a common phenomenon which causes phase fluctuations of GPS signals. We distinguished TEC variations related to ionospheric structures of a spatial scale bigger than 200-300 km. In the diagram of temporal variations of TEC along satellite passes, the structure of TEC corresponds to a time scale longer than 15-30 min. We attribute the variations in a time scale smaller than 15-30 min to TEC fluctuations related to small-scale ionospheric irregularities. We used the rate of TEC index (ROTI) expressed in TECU/min as a measure of TEC fluctuations. Large-scale ionospheric structures cause an increase in horizontal gradients and difficulties with the carrier phase ambiguity in relative GPS positioning. In turn, the phase fluctuations can cause cycle slips. At polar stations MCM4, CAS1, DAV1 we detected ionospheric structures of TEC enhanced 3-5 times relative to the background, whereas TEC increased to 10-30 TECU in about 10-15 min. The structures were observed during a storm, as well as during moderate geomagnetic activity. The structures can be probably attributed to polar cap patches. During storms the intensity of phase fluctuations increased. The occurrence of phase fluctuations was even detected during the active storm period of 31 March 2001 at a middle-latitude station OHIG (located at 49° corrected geomagnetic lati-tude).

15

Participation of Lamkowko satellite observatory in ionospheric researches

Baran L., Krankowski A., Shagimuratov I., Wielgosz P.

Reports on Geodesy

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2003

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z. 2/65

195-202

EN

The ionospheric studies have been carried since 1995 by Institute of Geodesy Warmia and Mazury University in Olsztyn jointly with West Department of the IZMIRAN of the Rnssian Academy of the Sciences in Kaliningrad. GPS measurements from 100 European EPN/IGS permanent stations were used to monitor the ionospheric effects of geomagnetic storms. A series of ionosphere maps were produced to present the spatial distribution of TEC. The dense network of GPS stations in Europe allows to obtain high spatial and temporal resolution of TEC. Our estimation technique provided TEC maps with 15min interval and with a spatial resolution of 150-350 km. As the examples we analysed geomagnetic disturbances, which occurred during the months of September 1999 and March 2001. It was found that the storm essentially modified the ionosphere. During the storm the large and medium-seale irregularities were detected in the high-Iatitude ionosphere as well as at middle latitudes. The deep spatial TEC changes were caused by oceurrence of the main ionospheric trough, which during the storm moved in the direction of the Equator (to latitude of about 50 st. N).

16

Influence of ionospheric storm on positioning precision

Baran L., Krankowski A., Shagimuratov I.

Reports on Geodesy

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2001

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z. 2/57

231-236

EN

In the paper results of analysis of the influence of ionospheric storm on positioning precision are presented. The analysis rely on studying of repeatability of vectors` coordinates. Different vector lengths (250 km-1300km) were studied. These vectors were investigated during the ionospheric storms.The permanent observations from IGS/EUREFstations were analysed. Those stations connect Borowiec, Borowa Góra, Lamkowo, Onsala, Mendeleevo, Kotwijk, Matera and Metsahovi. Their latitudes range from 41(st.)N to 60 (st.)N. Software Bernese ver. 4.0 was used for the analysis of observational data of the six and twelve-hours sessions. Results were refered to those otained from 24-hours sessions.

17

Wpływ jonosfery na opracowanie permanentnych obserwacji GPS ze stacji położonych na szerokościach okołobiegunowych

Baran L.W., Krankowski A.

Geodezja / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2001

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T. 7, z. 2

131-139

PL

W pracy przedstawiono wyniki badań nad wykorzystaniem ciągłych obserwacji GPS - ze stacji uczestniczących w międzynarodowym programie IGS (International GPS Service) - do śledzenia dobowych i sezonowych zmian całkowitej koncentracji swobodnych elektronów TEC (Total Electron Content) nad szerokościami okołobiegunowymi. Prowadzenie ich równolegle z monitorowaniem stanu jonosfery wyznaczania dzień po dniu współrzędnych wektorów łączących stację Onsala (57,3 st. N, 11,9 st. E) z siedmioma innymi stacjami IGS: Hoefn (64,2 st. N, -15,2 st. E), Thule (76,5 st. N, -68,8 st. E), Kiruna (67,8 st. N, 20,9 st. E), Ny-alesund (78,9 st. N, 11,9 st. E), Reykjavik (64,1st. N, -21,9 st. E), Tromso (69,6 st. N, 18,9 st. E) i Metsahovi (60 st. N, 24 st. E) pozwoliło ujawnić wyraźną korelację między zmianami wartości TEC występującymi w okresie spokojnej i zaburzonej jonosfery a zmianami wartości współrzędnych wektorów o zróżnicowanych długościach (od 784 km do 3622 km). Analizowano okresy trzech zaburzeń jonosferycznych z 1999 roku (11-16 września, 27-30 września, 10-15 października). Obserwacje opracowano za pomocą software'u Bernese ver. 4.2. 8- i 12-godzinne sesje obserwacyjne porównano z wynikami otrzymanymi w oparciu o całodobowe permanentne obserwacje GPS. Zmiana stanu jonosfery w największym stopniu wpływa na składową pionową U punktu w trójwymiarowym lokalnym układzie współrzędnych N E U. Wartości tej współrzędnej w okresie zaburzeń jonosfery mogą różnić się nawet o 160 milimetrów w stosunku do wartości uzyskiwanych w okresie spokojnej jonosfery

EN

In the paper, results of analyses of the influence of the northern ionosphere on positioning precision were presented. The analyses rely on studying of repeatability of vectors' co-ordinates. These vectors were investigated during the ionospheric storms. The IGS permanent observations from three periods of the ionospheric storms from 1999 year: 11-16 September, 27-30 September and 10-15 October, were analysed. Those stations connect Onsala (57,3 degree N, 11,9 degree E), station with following GPS observatories: Hoefn (64,2 degree N, -15,2 degree E), Thule (76,5 degree N, -68,8 degree E), Kiruna (67,8 degree N, 20,9 degree E), Ny-alesund (78,9 degree N, 11,9 degree E), Reykjavik (64,1 degree N, -21,9 degree E), Tromso (69,6 degree N, 18,9 degree E) and Metsahovi (60 degree N, 24 degree E). Their latitudes rangę from 57 degree N to 80 degree N. Software Bernese ver.4.2 was used for the analysis of observational data of the eight and twelve-hours sessions. Results were referred to those obtained from 24-hours sessions. Because of the great dynamics of the TEC during the ionospheric storms the special attention should be paid to the differences of vectors co-ordinates obtained from semidiurnal GPS sessions

18

The fifth year of the activity of the Lamkowko IGS permanent station

Baran L. W., Kapcia J., Krankowski A., Shagimuratov I. I., Wielgosz P.

Geodezja i Kartografia

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1999

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T. 48, z. 3-4

159-167

EN

In the paper, there is presented activity of the Lamkowko Satellite observatory of the Institute of geodesy in regional and global geodynamic programmes. there are shown some results of studies concerning monitoring of the Lamkowko-Borowiec, Lamkowko-Onsala and Lamkowko-Matera vectors and possibilities of the use of the permanent GPS observations to study local ionosphere changes.

PL

Artykuł prezentuje działalność obserwatorium satelitarnego Lamkówko Instytutu Geodezji w ramach programów geodynamicznych regionalnego i globalnego. Przedstawiono wyniki badań monitoringu wektorów Lamkówko-Borowiec, Lamkówko-Onsala i Lamkówko-Matera wraz z możliwościami wykorzystania stałych obserwacji GPS w badaniach miejscowych zmian jonosfery.