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Volume 40 (1994)
- Issue 4 Pages 301-
- Issue 3 Pages 215-
- Issue 2 Pages 101-
- Issue 1 Pages 1-
Volume 40, Issue 4
Displaying 1-6 of 6 articles from this issue
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Jan Kostelecký, Milan Talich, Pavel Vyskocil1994 Volume 40 Issue 4 Pages 301-308
Published: December 25, 1994
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe transformation of the displacement vectors due to the surface movements into the parameters of deformations is one of the possible tool for better expressions of dynamical properties for recent movement studies. The different kinds of such a transformation are discussed. In addition to the simple determination within triangles, the approximation of displacements and parameters of deformations are given . The procedure for data processing in 2-dimensional or 3-dimensional expression, either in simple way or in kind of regular, rectangular grids, used for data processing in the International Center on Recent Crustal Movements (ICRCM) is described. The 3-dimensiodal expression of phenomena is presented as well, with limitations of using the results of geodetic methods only. In general, for the approach to modelling of displacements and deformations, the whole combination of geodetical-geophysical methods should be applied.View full abstractDownload PDF (1967K) -
Yukio Takahashi1994 Volume 40 Issue 4 Pages 309-331
Published: December 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSI estimate the individual observation data errors and the parameter errors in the geodetic VLBI. I describe (1) that the error during the estimation period is also important in addition to the individual observation errors, (2) that we must consider the atmospheric scintillation error in addition to the observation error and that the estimated parameter errors may be reduced by increasing the number of observations rather than by using a large SNR, (3) a formulation to estimate theoretically the station position error for uniform observations in the standard VLBI, (4) the suitable observations to measure the positions in the domestic VLBI, (5) a proposal for a new method to obtain realistic individual observation data error in geodetic VLBI instead of using the noise error by SNR, (6) estimates concerning the additional error of ionospheric delay correction obtained by the GPS system and I indicate the possibility of single band VLBI observation. These estimation of error can be applied to other geodetic measurements such as error estimations in SLR and GPS.View full abstractDownload PDF (2416K) -
Kin-ichiro Koizumi, Hiromi Fujimoto, Hiroo Inokuchi, Masashi Uchitsu, ...1994 Volume 40 Issue 4 Pages 333-345
Published: December 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSSurface ship gravity measurements on board the R/V Tansei-maru, Ocean Research Institute, University of Tokyo, were carried out over the Seto Inland Sea, western Japan. This region is one of the widest vacant area of gravity data in and around the Japanese Islands. During the cruise for full 4 days, gravity data were obtained at more than 6000 points. The ship was forced to change courses frequently due to steering clear of many islands and ships, so that we examined the gravity data carefully. Based on the analyses of variation of measured gravity values due to changes of ship's heading and those of crossover errors at intersections of the ship's track, it was confirmed that the most of error data were generated when the ship changed her course. Most of error data were detected by assuming an upper limit of horizontal gravity gradient to be 10 mgal/km, which value is appropriate for land gravimetry. We omitted about 350 data from measured one after these analyses . A drift effect was also corrected based on gravity values at ports of calls. After these processings, most of the gravity data are estimated to be accurate to 3-4 mgals. Obtained gravity anomalies in and around the Seto Inland Sea revealed a narrow(about 30 km width) and low (several tens mgal) gravity anomaly zone along the north of the Median Tectonic Line. This zone continues at least from Beppu Bay in the west to Osaka Bay in the east.View full abstractDownload PDF (4235K) -
Toshimichi Otsubo, Hiroo Kunimori, Bret Engelkemier, Fujinobu Takahash ...1994 Volume 40 Issue 4 Pages 347-355
Published: December 25, 1994
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSThe Communications Research Laboratory (CRL) is developing the orbit-analysis software CONCERTO for data processing of Satellite Laser Ranging (SLR) . CONCERTO shares many common physical models and constants with the operational Very LongBaseline Interferometry (VLBI) software previously developed by CRL. In the numerical integration procedure, the modified Encke's method is introduced to curb the round-off error. The modified back differences method has been improved to eliminate the acceleration discontinuity in the orbit integration . As a result, the error in the computational process remains less than 1 cm in a one-month integration of the LAGEOS satellite.View full abstractDownload PDF (1611K) -
Fumiaki Kimata, Shinichi Sakamoto1994 Volume 40 Issue 4 Pages 357-365
Published: December 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSBaseline vectors are determined for three GPS baselines ranging from 110 km to 412 km using broadcast ephemerides and precise ephemerides by CODE and GSI in the period from June 1992 to March 1993. Baseline determinations are processed with triple difference algorithm on Trim VecTM automatically. Long-term repeatability of horizontal baseline components processed using precise ephemerides is improved more than 1.7 to 1.3 times than those using broadcast ones, and shows 1.0x10-7. It is clearly necessary to use the precise ephemerides for detailed discussions of the crustal movements.View full abstractDownload PDF (3766K) -
Takeyasu Yamamoto1994 Volume 40 Issue 4 Pages 367-375
Published: December 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSGeoid undulation differences were precisely investigated by employing both GPS/levelling and surface gravity data in the southwestern part of Japan. First, geoid differences were evaluated only from gravity data with the FFT method, and the geoid differences evaluated were then compared with the GPS/levelling ones. As a result, those two geoid differences were generally consistent within errors of 10 cm or so, but in some regions, there were large discrepancies more than 20 cm which were mainly related to the insufficiency of gravity data or a rough topography. In order to confirm those results, GPS/levelling geoid differences were newly determined at 8 sites in that region. Consequently, the geoid differences determined supported the results mentioned above. It was revealed that the interpolation of GPS/levelling geoid differences obtained at intervals of about 50 km by employing gravity data is effective to avoid errors of geoid differences which were caused by insufficient gravity data and so on. Finally, geoid differences were evaluated with a precision of 10-15 cm in the southwestern part of Japan.View full abstractDownload PDF (1752K)
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