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Volume 41 (1995)
- Issue 4 Pages 357-
- Issue 3 Pages 227-
- Issue 2 Pages 117-
- Issue 1 Pages 1-
Volume 41, Issue 4
Displaying 1-4 of 4 articles from this issue
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Masaki Kanao, Kazuo Shibuya, Kazuo Watanabe, Satoshi Fujiwara, Hisao I ...1995 Volume 41 Issue 4 Pages 357-364
Published: December 25, 1995
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThere are four reference points by different space geodetic techniques at Syowa Station (69.0°S, 39.5°E), Antarctica; satellite Doppler point, Very Long Baseline Interferometry (VLBI) reference point, Scientific Committee on Antarctic Research (SCAR) Global Positioning System (GPS) point and Doppler Orbitography by Radiopositioning Integrated by Satellites (DORIS) beacon point. Local geodetic ties among these reference points were made, taking several occasions. GPS relative positioning was made at the periphery of the 11 m S/X-band parabolic antenna reflector with respect to the SCAR GPS point. The center location of the peripheral circle of the reflector pointing at zenith was estimated by a nonlinear least squares method with a set of geocentric coordinates of the attached GPS antenna locations. Since the separation between the VLBI reference point and the reflector center determined above is known from the mechanical design, relative location of the VLBI reference point (R) to the SCAR GPS point (G) can be estimated. The accuracy of the obtained offset vector RG = (-11.69 m, -74.08 m, -12.01 m) was ±0.26 m, ±0.25 m and ±0.07 m for each component. As for local tie between the DORIS beacon point and the SCAR GPS point, and between the satellite Doppler point and the SCAR GPS point, the accuracy of the obtained offset vector is within 1 cm for each component.View full abstractDownload PDF (726K) -
Atsushi Mukai, Toshihiro Higashi, Shuzo Takemoto, Isao Naito, Ichiro N ...1995 Volume 41 Issue 4 Pages 365-378
Published: December 25, 1995
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSGravity changes in the tidal band are contaminated by atmospheric pressure tides and thermal effect of the convective boundary layer on the atmospheric tides. We discussed atmospheric effects on gravity observations at Kyoto by applying Integration Method to local, regional and global meteorological data, and examined characteristics of these effects within the diurnal band. First, the effect of atmospheric pressure tides inside 0.43°was calculated and the result of calculation was compared with the observational data obtained from the superconducting gravity meter TT-70 #009 at Kyoto. The result shows that the calculated effect has a larger amplitude by an amount about 50% than the observed one. Second, we examined whether the deviation of the calculated effect from the observed one could be smaller by introducing global atmospheric pressure tides whose variations at any location were assumed to be in proportion to the observed ones at Kyoto. The effect of atmospheric pressure tides outside 0.43° from the gravity station is corresponding to 20-50% of that inside this zone. The result of calculation including the effects beyond 0.43°is closer to the observed one, but there remained 5% deviations between the calculated and observed atmospheric effects. Third, we thus investigated local thermal effect of the convective boundary layer on the atmospheric tides at Kyoto in detail. The thermal effect is significant at Si and is corresponding to 40% of atmospheric pressure tides at most. Therefore, the vertical profile of temperature around the gravity station cannot be neglected for the calculation of atmospheric effects in the diurnal band. Consequently, it is revealed that atmospheric effects within the diurnal band can be estimated by employing global atmospheric pressure tides as well as local thermal effect of the convective boundary layer on the atmospheric tides around a gravity station. We should be able to calculate atmospheric effects more accurately, if global distributions of observational data of pressure and temperature changes are available at intervals of lh.View full abstractDownload PDF (1494K) -
Ryuichi Ichikawa, Minoru Kasahara, Nobutaka Mannoji, Isao Naito1995 Volume 41 Issue 4 Pages 379-408
Published: December 25, 1995
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSWe compare the zenith wet delays estimated from the global analysis data sets produced by Japan Meteorological Agency (JMA), with those obtained by the radiosonde data sets at eight stations in Japan. Both estimates agree well with each other in both amplitude and phase through nearly one year. The rms of their differences is of the order 1.5-3.0 cm and it indicates that the numerical prediction data is available to estimate the wet delay. Next, we calculate the atmospheric excess path delays by ray tracing based on the JMA 10 km spectral model data (10 km data) to evaluate its variability considering azimuthal asymmetry of atmosphere by comparing with the delay estimated by the spherically symmetric atmosphere. The 10 km data is produced every three hours from 1200 UTC 28 to 1200 UTC 29 June, 1989, with a spatial width of about 800×800 km. The precipitable water vapor predicted by the 10 km data is good consistent with that observed by radiosonde within 0.5 cm rms. The difference of wet delays at both ends of the baselines (differential wet delay) at the elevation of 15° exceeds 60 cm, in maximum when baseline directions are parallel to the horizontal gradient of water vapor. At the same baseline directions and elevations angle, the differential wet delay due to the azimuthal asymmetry more than a few centimeters distributes in local scales of 50-300 km width and in synoptic scales along the cold front. The maximum differential wet delay reaches up to 6 cm. When the temperature gradient is significant, the differential hydrostatic delay due to the azimuthal asymmetry at 15° elevation angle exceeds 1 cm. These results imply that the estimation of atmospheric excess path delay considering spatial distributions of water vapor is indispensable to attain the ultimate accuracy of space geodetic technique.View full abstractDownload PDF (12213K) -
Shigeki Hosokawa, Yoji Shimada, Yoshio Sumino1995 Volume 41 Issue 4 Pages 409-412
Published: December 25, 1995
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSFor the purpose of detecting the crustal deformation associated with the volcanic activity, interferometric GPS measurements have been carried out at and around the Yakedake Volcano, central Japan. Five GPS campaigns were conducted in October 1992, August and September 1993, and June and October 1994. The Yakedake GPS network consists of three stations, namely, Kamikochi, Nakao and Yakedake stations. The Kamikochi and the Nakao stations are located at the foot of the volcano. The Yakedake station is located at Yakedake Observation Platform which is close to the top of the mountain, and lies halfway between the Kamikochi and the Nakao stations. Each campaign continued a few days with a daily several-hour session, and was made by using single and dual frequency receivers, namely, Trimble 4000SL, 40005E, and 4000SST. These GPS mesurements clarify that the Yakedake station moved 26±4 mm north-eastward, and subsided 20±5 mm during the period between the first (Oct., 1992) and the fifth (Oct., 1994) campaigns. These results may suggest the possibility of the regional inclination of the Yakedake Volcano. However, no significant crustal deformation associated with the volcanic activity of Yakedake was detected during the period 1992-1994.View full abstractDownload PDF (545K)
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