Abstract:

The Sea III gravimeter is a new type of pendulum-sliding zero-length spring sea gravity-measuring instrument developed by Micro-g LaCoste manufacturer based on the principles of the LaCoste & Romberg SII gravimeter. In this paper, we have done a performance test of the Sea III gravimeter on Xuelong 2. Firstly, we gave a comprehensive introduction of its working principles, calculate formula and structural characteristics in order to describe the advantage of the Sea III gravimeter. Then the performance of the instrument had been tested both in a static and dynamic way. Xuelong 2 has been designed to sail in a repetitive lane to evaluate its dynamical accuracy. The tests show that the static linear drift rate of the Sea III is about 3.28 × 10⁻¹² m·s² while the gravimeter records present a clearly characteristic of local earth tide. The dynamic internal compliance accuracy is about 0.23 ×10⁻⁵ m·s², which is far better than the relevant marine survey specification standards. Besides that, the type of Xuelong 2 icebreaker, its equipment layout, gravimetric data processing flow and instrumental performance evaluation are all documented in order to provide a meaningful reference for future users.

Key words: marine gravimeter, Sea III, Xuelong 2, monthly drift, dynamic accuracy