Assessment of geoid models for geopotential values determination in Mexico'S continuous monitoring network

Abstract

The requirements of the reference systems related to the vertical part are aimed at adopting a global height system that allows taking advantage of the development of satellite technology that provides terrestrial data with higher quality. Due to this need, the International Association of Geodesy (IAG) has proposed the realization and implementation of the International Height Reference System (IHRS), based on geopotential numbers obtained from the gravity potential difference at a point on the Earth's surface (W(P)) referred to the geoid (W₀), whose value adopted by convention corresponds to 62636853.4 m²s^-2. Nowadays, efforts are underway worldwide to materialize this system. Considering this, the present work entails the analysis of information gathered from SIRGAS continuous monitoring stations in Mexico: MTY2, IDGO, INEG, MERI, and ICAM, to estimate its gravity potential from sufficiently precise geocentric coordinates and absolute gravity values, which when combined with heights derived from geoid models, allows obtaining a modern height system such as the IHRS. The analysis aims to evaluate the feasibility of estimating the gravity potential at the stations, by using precise geocentric coordinates and absolute gravity values which when combined with high-resolution geoid models such as EGM2008, GGM10, EIGEN6C4, XGM2019e_2159, SGGUGM2, and the xGEOID20B, to implement a modern height reference system in Mexico; as well as to contribute to the International Height Reference Framework (IHRF), which in its latest version only includes the MERI station, located in Mérida, Yucatán. Therefore, we consider that for their characteristics the stations analyzed can be included to densify the frame in the implementation of the system. The results show the differences in gravity potential in the different regions of the country, reinforcing the need to consider more reference stations. Additionally, benchmark points close to the selected stations were analyzed to determine the reference potential value of the GGM10, with which it was also possible to analyze the behavior between the observed geoid and the different geoid models, toward the modernization of the official height system, which is based on orthometric heights called NAVD88, which shows us the differences between the geoid observed with the official height system and the analyzed models. Finally, the study examines the consistency of the calculated orthometric heights with geopotential numbers derived from the different geoid models.