Kazuo Shibuya

Polar Motion Effect on Gravity Observed with a Superconducting Gravimeter at Syowa Station, Antarctica

Polar motion effect on gravity was analyzed using the 2 years data obtained with a superconducting gravimeter at Syowa Station, Antarctica. From the analysis, we obtained the amplitude factor (δ-factor) of 1.198±0.035 and a time lag about 20 days against to the gravity changes predicted from the IERS (International Earth Rotation Service) polar motion data. Our analysis using simulation data suggests that the results for least-squares fitting are affected by the accuracy of the correction for step-like changes in the observed gravity data.

Geodetical and Geophysical Observations at Syowa Station, Antarctica

A Japanese Antarctic Station Syowa (69°S, 39°E) was established in East Ongul Island, Lutzowholm Bay, East Antarctica for the International Geophysical Year (IGY) in 1957. Since that time, the following geodetical and geophysical observations have been carried out in the vicinity of Syowa Station: 1. Gravity: a) Continuous recording of gravity for detecting earth tides using LaCoste-Romberg gravity meter type D and G. b) Continuous observation by a superconducting gravimeter was started in March 1993; 2. Oceanic tide: Continuous recording since 1966; 3. Geomagnetism: a) Base line measurment. b) Continuous recording of long-period and short-period geomagnetic variations, and total intensity; 4. Seismology: Continuous recording by the three-component of long-period, short-period and broadband digital seismographs; 5. GPS/DORIS becon: Tracking continuously.