GGOS-SIM: Simulation of the reference frame for the global geodetic observing system

Abstract

The accuracy and stability requirements for the International Terrestrial Reference Frame (ITRF) postulated by the Global Geodetic Observing System (GGOS) are not met so far. The GGOS–SIM project builds a software tool that by simulating the space geodetic infrastructure allows to assess the impact of technique upgrades, new sites, new satellites, local ties, and space ties on the ITRF accuracy and stability. As also the procedure for the combination of the techniques plays a fundamental role in the generation of an ITRF, we discuss peculiarities of current day approaches and draw conclusions relevant for this project. As the assessment of the accuracy of an ITRF is needed for checking against the GGOS requirements, we compile actualmethods and present here a new measure of stability which is exemplarily applied to recent ITRFs.