GravNetAdj: a MATLAB-based data processing software for gravity network adjustment

In order to realize the gravity standard using the gravity data of a specified group of stations, the gravity reference network is crucial for national gravity measurements. Dependable gravity values are required in the modern height system and for different tasks in geophysics. In particular, it can be utilized as an initial data point for airborne gravity measurements or other fields. There are some programs for processing gravity data like GrafLaB, GRAVSOFT, but its main focus are the spherical harmonic computation and gravity field modeling, and can not process the observations of relative measurements. Even though there are pyGABEUR-ITB and GRAVNET, but above mentioned software don't have the graphical user interface (GUI) and also don't give the detail mathematical error correction. Therefore, the GravNetAdj software package, which is based on the MATLAB 2018a platform by using the appdesigner, is developed using an up-to-date robust method for parameter estimation. Firstly, this paper reviews the fundamental theory of gravity network adjustment, covering the relative gravity data processing, the methods of network adjustment, and precision evaluation. Then, a case study for the local gravity reference network in China is conducted, which is used to prove the reliability and availability of the presented software.