An overview of SIRGAS activities towards the IHRF

G. DO NASCIMENTO GUIMARÃES; ANA CRISTINA OLIVEIRA CANCORO DE MATOS; AYELEN PEREIRA; E. D. ANTOKOLETZ; J. L. CARRIÓN SANCHEZ; L. SÁNCHEZ

Beijing

Otro; Asamblea Científica de la IAG (International Association of Geodesy), ?Geodesy for a sustainable Earth?; 2021

International Association of Geodesy

Since 2015, when the International Association of Geodesy defined the International Height Reference System, SIRGAS has been focusing efforts on this topic. SIRGAS Working Group III ?Vertical Datum? has the aim to establish, maintain and update a unified physical height system for the Americas and the Caribbean, following the recommendations of the International Association of Geodesy. For this reason, SIRGAS WG-III is in charge of this task and, since then, some activities related to the International Height Reference Frame (IHRF) have been carried out. This presentation has the purpose to show an overview of SIRGAS activities towards the IHRF, especially in Central and South America. National leveling networks based on geopotential numbers, international leveling crossings, and leveling connections with IHRF stations are an important task for the countries and part of the activities related to the IHRF. In the last years, SIRGAS has been promoting and supporting some capacities related to this topic. In terms of gravity data, the distribution and amount of data around the selected stations, as well as absolute gravity measurements in each place have been analyzed. To support the SIRGAS community, technical guides have been developed as well. These guides are related to strategies for the selection of the IHRF stations and gravity measurements around them, and also, to ensure the usability and long‑term sustainability of the IHRF. Besides that, three activities are ongoing in the working group: the evaluation of the geoid models and GNSS/leveling stations available in Latin America using high-resolution gravity field models; the investigation related to the combination of satellite and ground-based data for the computation of geopotential values at the IHRF stations; and the first estimation of IHRF values using geoids and quasi geoids models available in the continent. In summary, SIRGAS has been contributing to the establishment of the IHRF in the continent.