The increasing demands on the accuracy of the International Terrestrial Reference Frame (ITRF), which have been set by the Global Geodetic Observing System at one millimeter and 0.1 mm/year stability, require the consideration of previously neglected influencing factors. These include non-tidal loading caused by atmospheric, oceanic, and hydrological mass redistributions, which can deform the Earth's crust by several millimeters to centimeters.

This work analyzes the impact of such deformations on GNSS time series using models from three different institutions. The evaluation is based on GNSS time series from the Nevada Geodetic Laboratory for 32 stations worldwide over a period of six years.

Special focus is placed on modeling hydrology, as these models show the greatest differences and hydrology causes the largest deformations of the Earth’s crust in most regions.

The results show that suitable correction models can improve the GNSS time series. However, the modeling of hydrology should be further refined and the results validated by additional stations and longer time periods.

Co-authors: Lukas Jendges und Susanne Glaser