Absolute gravity measurements in Australia and Syowa station, Antarctica

Abstract

Absolute gravity measurements have been carried out in Perth and Canberra, Australia, and at Syowa Station, Antarctica, as a part of activities of the 45th Japanese Antarctic Research Expedition during 2003-2004.Using a FG-5 (#210), the measurements in Perth were conducted at the Perth Observatory on November 25 and 26, 2003, and those in Canberra were conducted at Mt Stromlo Observatory and at Tidbinbilla Deep Space Tracking Station from March 26 to April 16, 2004.The gravity values obtained at the Perth observatory, Mt Stromlo and Tidbinbilla are 979403619.9 μGal, 979549870.7 μGal and 979576114.3 μGal, respectively. Using a FG-5 (#111), Geoscience Australia and Micro-g Solutions occupied the same points at Perth and Tidbinbilla in June 2003.The gravity values at Tidbinbilla agreed very well at 0.1 μGal, while the values at Perth differed by 13.4 μGal due to unknown causes. The measurements at Syowa Station, Antarctica were carried out using two FG-5s (#210 and #203) from December 30th, 2003 to February 1st, 2004.There is a category "A" point of the International Absolute Gravity Base Station Network (lAGBN) in the gravity observation hut at Syowa Station. The gravity values obtained by #203 and #210 are 982524322.8 μGal and 982524324.5 μGal, respectively such that both agreed at 1.7 μGal. There are two previous gravity values obtained by a FG-5 in 1995 and 2001.The secular rate of the gravity changes estimated from the values is -0.27±0.42 μGal/yr. This value is consistent with an estimated rate from postglacial rebound models.