Test Results of FG5/112 Absolute Gravimeter at Wuhan Station
From December 1995 to April 1996, the test of FG5/112 absolute gravimeter was carried out in Wuhan. The meter was installed in the underground laboratory (depth 22 m) of Institute of Geodesy and Geophysics, with a very stable bedrock and a small temperature variation. The main purpose of this work is to test the accuracy and repeatability of FG5/112 meter. There are totally 14 measurements during the whole test period, about three times per month, and each measurement includes 12 sets and 100 drops per set. The results show the standard deviation of one drop is less than 10 µgal, and the rms of each measurement is within 1.2 to 1.9 µgal. In addition, we found that a very close correlation exists between the gravity and atmospheric pressure inside the laboratory, the correlation coefficient is more than 0.85 and an admittance of −2.29 µgal/mbar is obtained by regression, that is in good agreement with that obtained from SG in Wuhan. The accuracy could be improved slightly by taking account of the ocean loading correction. We have also made a repeated measurement by FG5/112 meter at WTUSM station and IOS station, respectively. The discrepancies between results obtained by FG5/112 and those by FG5/101 are 2 µgal, and 8 µgal between FG5/112 and JILAG-3.
KeywordsLocal Atmospheric Pressure Polar Motion Underground Laboratory Gravity Observation Absolute Gravity
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