Performance of invariants of gravity gradient tensor in matching navigation: A case study in South China Sea

Choosing appropriate background field data is crucial for gravity field matching navigation. Current research mainly uses gravity anomaly data or gravity gradient data as background fields. However, using gravity gradient invariants in existing research is seldom a concern. The gravity gradient tensor has three invariants, named as I 1 , I 2 and I 3 . I 1 is a Laplace operator outside the Earth and a Poison operator inside the Earth. The focus of this study is to discuss the performance of the other two invariants of gravity gradients in matching navigation based on the Iterative Closest Contour Point (ICCP) algorithm and compare the matching results with that of the gravity gradient T z z . The results show that they have almost the same performance when there is no noise, and the background data noises have a large impact on the matching results. There are differences in the anti-interference ability of observation noises for the different components. Under the same random noises in the observations, I 2 performs a little better than the other two components in terms of position error standard deviation. According to the investigations, since attitude errors can not be avoided and influence the positioning based on T z z , we recommend adopting invariants of gravity gradients, especially I 2 , for matching navigation in actual cases.