Measurement of Vertical Gradient of Gravity Using Absolute Gravimeter

Abstract

　The FG5 absolute gravimeter yields estimates of the gravity acceleration typically at the height of 130 cm above the floor. In order to transfer the gravity value to another height such as the surface of the floor, precise knowledge of a vertical gradient of gravity acceleration is necessary. Gravity gradients are commonly measured by using relative gravimeters, but limited precision in relative gravity measurements leads to less precise values of the transferred gravity. In this study, a trial was made to measure the vertical gravity gradient using the FG5 absolute gravimeter. Absolute gravity measurements were made at two different heights with vertical separation of about 13 cm at the gravity station in Mount Fuji Research Institute, Yamanashi, Japan. As a result, relative precision of about 0.5％ was established for the estimate of the vertical gradient of gravity.