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Volume 38 (1992)
- Issue 4 Pages 315-
- Issue 3 Pages 211-
- Issue 2 Pages 89-
- Issue 1 Pages 1-
Volume 38, Issue 3
Displaying 1-10 of 10 articles from this issue
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Shuzo TAKEMOTO, Takeyasu YAMAMOTO, Atsushi MUKAI, Tadahiro SATO1992 Volume 38 Issue 3 Pages 211-219
Published: October 25, 1992
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSThe response of the Earth to the surface load due to oceanic tides depends strongly on the locally variable properties of the crust and upper mantle, whereas that to the bodily tidal force depends more on the Earth's overall properties . It can be expected to obtain a useful information about the elastic properties of the Earth's crust from signals caused by oceanic tidal loading. We thus compared tidal strains observed with laser strainmeters at three stations (KISHU, ROKKO-TAKAO and AMAGASE) in Kinki district with theoretically expected ones including the oceanic tidal loading effect calculated for four Earth's models (1066A, GUTENBERG-BULLEN, OCEANIC MANTLE and SHIELDED MANTLE). As a result, it was suggested that phase lags of observed tidal strains relative to theoretically expected ones differed systematically according to the latitude. At the present stage, however, differences between observed tidal strainsand theoretically expected ones are too large to be used to determine which model is fit for Kinki district. This may be due to local disturbances caused mainly by groundwater flows around the observation stations.View full abstractDownload PDF (1188K) -
Hideo HANADA1992 Volume 38 Issue 3 Pages 221-237
Published: October 25, 1992
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSIt is possible to detect the non-Newtonian gravity due to the Earth's mass by measuring gravity gradient over a wide range of altitude since there is a characteristic pattern in the relation between the value of the non-Newtonian gradient and the altitude on a logarithmic scale. The value of the non-Newtonian gravity gradient on the Earth is estimated at about a×10-6s-2 where α is the coefficient of the additional YUKAWA term. The effects of harmonics of gravity potential with degrees higher than 3 and uncertainty of density of the Earth's interior, on the other hand, are less than 10-10s-2 and they can be corrected to as small as in the range of 10-12s-2 with an reliable Earth model, which is equivalent to the non-Newtonian gravity gradient in the case of α=10-6. A gravity gradiometer with a couple of superconducting accelerometer or that with high sensitive Fabry-Perot interferometer can have the sensitivity better than 10-13s-2 and it is the most effective for the detection of the non-Newtonian gravity on the Earth . The non-Newtonian gravity gradient due to the Earth is detectable if the coefficient α is larger than 10-6 and the range λ is shorter than 105 m by the gravity gradient measurement.View full abstractDownload PDF (1643K) -
Masaaki MURATA, Toshiaki TSUJII1992 Volume 38 Issue 3 Pages 239-250
Published: October 25, 1992
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe Etalon satellites as the former USSR's laser geodynamic satellite array composed of two satellites Etalon-1 and Etalon-2. Satellite laser ranging data to Etalon satellites collected during the 5-month period from August to December 1990 centered on the 3- month period of the IERS Etalon Intensive Campaign (September 1 to December 1, 1990) has been used to evaluate the scientific potential of Etalon in the determination of geodetic/geodynamic parameters. The new Etalon solution for station coordinates and earth orientation parameters was obtained by application of the global least-squares adjustment to 3-minute normal points (NPs) created at National Aerospace Laboratory (NAL) from full-rate Etalon data. Estimation strategies specific to this solution are as follows: use of long arc length of 50 days and the combined Etanol-1 and Etalon-2 NP is made to enhance geometrical strength of the sparsely distributed data; scale factors for along-track acceleration and solar radiation pressure are adjusted twice per satellite, i.e. over each 25 days; 5-day averages of pole position are estimated; and UT1-TAI is modeled to be a piecewise linear function over each 5-day interval and the value at each break-point is estimated except for the arc-epochal value which is kept fixed with that taken from the IERS Bulletin B. The satellite state vectors at each arc epoch are a justed once over the arcs. The station coordinates are uniquely determined as common parameters from three 50-day arcs. For comparison, various other Etalon solutions have been derived with different analysis strategies changing the arc length, the number of satellites, and the parameters to be solved-for. The resulting Etalon solutions were compared with the existing solutions, the IERS Terrestrial Reference Frame 1990 (ITRF90) and the newest Lageos solution (NAL92L01) derived from analysis of Lageos long arcs of 7.8 years (September 1983-May 1991). The comparisons show that the new Etalon solution is generally consistent with the existing solutions and yields better accuracies than the other Etalon solutions derived with different estimation strategies. It is concluded that Etalon data complement Lageos and have substantial promise for geodetic/geodynamic applications.View full abstractDownload PDF (1460K) -
Izuo OZAWA1992 Volume 38 Issue 3 Pages 251-257
Published: October 25, 1992
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSObservations of the earth tidal strains in the directions of NS and EW at Suhara observatory which is located on the coast have been performed. The component tides (M2, O1 and S2) of the strains are analyzed for the period of about 200 days. The direct tides and load tides caused by the ocean and the atmosphere are subtracted from the observed components, and their residual strains are obtained. M2-components of the residual strains are obtained as 10.7×10-9 cos (2t-35 .4°) in the NS-direction and 10.1×10-9 cos (2t-10.4°) in the EW-direction. Where t is the local time of the M2 tide. Their amplitudes and phases are almost equal each other in the orthogonal directions. Therefore, it is reasonable to presume that the residual strain is caused by tidal oscillation of the pressure of ground water under the observing site which is connected to the hydrostatic pressure at the sea floor near the Observatory.View full abstractDownload PDF (1657K) -
[in Japanese]1992 Volume 38 Issue 3 Pages 259-266
Published: October 25, 1992
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe accuracies of determining quasigeoid heights and deflections of the vertical at all stations required for the reduction in the projection method and for the simultaneous adjustment are investigated. It is concluded that they should be determined with the accuracies of ±1 m and ±1" respectively for the adjustment.View full abstractDownload PDF (1003K) -
Shigeyasu ONO1992 Volume 38 Issue 3 Pages 267-274
Published: October 25, 1992
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSAccuracies of the rotation rates and strain rates, which are determined by the least squares adjustment using the Earth model, depend entirely on the spatial and temporal distributions of the existing data. The accuracies have been investigated . It is concluded that the existing data are too poor to solve the problem to determine a model allowing appropriate spatial resolution. A convenient method to process local high precision geodetic networks, which are constructed to investigate horizontal crustal movements for selected local areas, by the projection method is proposed. In this method we calculate first gravimetric deflections of the vertical using gravity anomalies only in the limited areas and then find quasigeoid heights by astronomic leveling without using astrogravimetric leveling.View full abstractDownload PDF (1070K) -
Shigeyasu ONO1992 Volume 38 Issue 3 Pages 275-282
Published: October 25, 1992
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe correction to the coordinate vector of each station is resolved in the geodetic horizon system of that station. The proposed method is more comprehensive than any method proposed until today, as in its model all astronomical observations (latitudes, l ongitudes, azimuths, and zenith distances) are treated as observed quantities .View full abstractDownload PDF (828K) -
Yukio TAKAHASHI1992 Volume 38 Issue 3 Pages 283-292
Published: October 25, 1992
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe station positions, earth rotation parameters, atmospheric delay parameters, and clock parameters are used to be estimated in the geodetic VLBI. The clock and the atmospheric delays irregularly change for each station during any experiments. Generally experiments are divided into several periods according to variations in time. These parameters are estimated for every period and are selected by a judgment of analyst, or the period of their estimation is automatically set (for a constant period) from 2 to 4 hours. The automatic estimation does not depend on the analyst's judgment and the work is simple. However, the estimation parameters are increased unnecessarily and the analysis is not based on physical considerations. We propose a more sophisticated method of estimation using the differential method. This method was applied to the clock estimation. It did not depend on judgments of analyst or need clock estimation. We made an analysis software using the differential method, and as an example it was applied to the domestic VLBI experiment between Kashima and Tsukuba in Japan. The results of the differential method were compared with the results achieved by the use of the normal analysis. This differential method can be used for some estimation parameter such as atmospheric delay parameter.View full abstractDownload PDF (759K) -
-Contribution to NASA Crustal Dynamics Project-Tetsuro KONDO, Jun AMAGAI, Yasuhiro KOYAMA, Hiroo KUNIMORI, Fujinobu T ...1992 Volume 38 Issue 3 Pages 293-308
Published: October 25, 1992
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe NASA Crustal Dynamics Project (CDP) started in 1979. The main objective of CDP is increase of scientific knowledge of crustal dynamics through measurements of A very long baseline interferometry (VLBI) technique in Japan was initiated and has been led by Radio Research Laboratory (RRL), present Communications Research Laboratory (CRL), since its beginning. CRL started development of VLBI system named K-3 in 1979 which was dedicated for precise geodetic measurements and compatible with Mark-III VLBI system developed in USA . At the same time NASA Crustal Dynamics Project (CDP) began to investigate global and regional crustal dynamics and earth orientation parameters by using space geodesy such as VLBI, satellite laser ranging (SLR), and global positioning system (GPS). CRL has participated in CDP VLBI sessions since 1984, and has significantly contributed to reveal contemporary plate motion, specially, the motion of the Pacific plate.View full abstractDownload PDF (1522K) -
Kosuke HEKI1992 Volume 38 Issue 3 Pages 309-312
Published: October 25, 1992
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESS
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