Research Activities : Space Geodesy

Space Geodesy stands for space based precise measurement techniques for Geodesy, which include Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), and Global Positioning System (GPS). Radio Astronomy Applications Section is studying Geodynamics by means of these Space Geodetic techniques, especially VLBI.

Key Stone Project (KSP)

KSP is the project to monitor regional crustal deformations in the Tokyo metropolitan area by using space geodetic techniques. The KSP has been started in 1993 by CRL.

• Overview
• KSP correlator
• Baseline Length Evolution
• Position of KSP VLBI Stations in the Local Horizontal Plane
• Correlated Amplitudes for 17 Radio Sources

Western Pacific VLBI Network (1989-1994)

Minamitorishima (Marcus Is.)

Western Pacific VLBI Network (WPVN) was deployed by CRL in 1989 to monitor the motion of two oceanic plates (Pacific and Philippine Sea plates) around Japan. The WPVN consists of three Japanese stations and one Chinese station on the four different plates, i.e., Kashima (North American plate), Minamitorisima (Pacific plate), Minamidaitojima (Philippine Sea plate), and Shanghai (Eurasian plate), respectively. We have detected the motion of Minamitorishima close to the NUVEL-1 plate motion model.

Details of the Western Pacific VLBI Network experiments and related research topics and developments were presented in the special issue of the Journal of the Communications Research Laboratory published in 1995 (Journal of the Communications Research Laboratory, Vol. 42, No. 1, 1995).

• I. Introduction by A. Sugiura
• II. Overview of the Experiment System
• II-1. The Main VLBI Station at Kashima by M. Imae et al.
• II-2. Station in the Remote Islands by T. Yoshino et al.
• II-3. The Western Pacific Geodetic Project's Data Acquisition and Processing System by H. Kiuchi et al.
• II-4. Data Processing Software and Data Analysis Software by Y. Takahashi et al.
• III. Geodetic Results of the Experiments
• III-1. Movements of the Minamitorishima Station by Y. Koyama et al.
• III-2. Movements of the Minamidaito Station by J. Amagai et al.
• III-3. Movements of the Shanghai Station : Implication for the Tectonics of Eastern Asia by K. Heki et al.
• IV. Related Results and Activities in Western Pacific VLBI Network
• IV-1. The Metropolitan Diamond Cross Experiments by T. Kondo et al.
• IV-2. Short Report of the Experiments with the Urumqi VLBI Station, Western China by T. Iwata et al.
• IV-3. Collocation and Local-Tie of Space Geodetic Techniques, VLBI, SLR, and GPS in CRL by H. Kunimori et al.
• IV-4. Radio Astronomy with the Kashima 34m Antenna by H. Takaba et al.
• IV-5. Experiments with the Southern Hemisphere by H. Kurihara et al.
• V. Conclusion Toward the Key Stone Project by F. Takahashi

NASA / Dynamics of Solid Earth Program

Precise Earth Rotation Measurements

Domestic Cooperations

• "Contributions and Activities of Communications Research Laboratory under the Cooperation with Crustal Dynamics Project", H. Kunimori et al., in Contributions of Space Geodesy to Geodynamics : Technology, eds. D. E. Smith and D. L. Turcotte, Geodynamics Series 25, American Geophysical Union (1995) pp.65-79
• "Horizontal Movement of Marcus VLBI Station due to the Pacific Plate Motion", Y. Koyama et al., Proceedings of CRCM'93, published as a special issue of the J. Geodetic Soc. Jpn. (1993) pp.117-122
• "Estimation of Errors in VLBI Data and Position Determination Error", Y. Takahashi, J. Geodetic Soc. Jpn., Vol.40 (1994) pp.309-331
• "Estimations of Atmospheric Excess Path Delay based on Three-Dimensional, Numerical Prediction Model Data", R. Ichikawa et al., J. Geodetic Soc. Jpn., Vol.41 (1995) pp.379-408
• "Excess Westward Velocities of Minamitorishima (Marcus) andin VLBI Stations in Addition to the Expected Velocities from Rigid Motion of the Pacific Plate", Y. Koyama, J. Geodetic Soc. Jpn., Vol.42 (1996) pp.43-57
• "Positioning Error in GPS Measurements due to Atmospheric Excess Path Delay Estimated from Three-dimensional, Numerical Prediction Model Data", R. Ichikawa et al., J. Geodetic Soc. Jpn., Vol.42 (1996) pp.183-204
• "Movements of VLBI Stations and the Effects of Ionospheric Delay Corrections on the Positions of the Domestic Experiments in Japan", Y. Takahashi et al., J. Geodetic Soc. Jpn., Vol.43 (1997) pp.45-65
• "Evaluation of repeatability of baseline lengths in the VLBI network around the Tokyo metropolitan area", Kondo et al, Geophys. Res. Lett., 25 (1998) 1047-1050