Abstract :
[en] The number of Global Navigation Satellite System (GNSS) satellites and their geometry
directly affect the quality of positioning and derived satellite products. Accordingly, the
International GNSS Service (IGS) recommends GNSS antennas to be installed away from
natural and man-made surfaces and structures, which may affect the incoming signals
through severe multipath or obstructions. Following these recommendations, continuous
GNSS (cGNSS) stations are generally located in low multipath environments with minimal
signal obstructions. However, some applications require GNSS antennas to be installed at
specific locations in order to measure local processes. In support of sea level studies, cGNSS
stations are established at or close to tide gauges in order to accurately monitor the local
vertical land movements experienced by the sea level sensors. However, the environment
at the tide gauge might not be optimal for GNSS observations due to the aforementioned
station-specific effects, which may degrade the quality of coordinate solutions. This study
investigates the impact of severe signal obstructions on long-term position time series for
some selected stations. A masking profile from an actually obstructed site is extracted,
simulated and applied to unobstructed IGS sites. To investigate these effects, we imple-
mented a new feature called azimuth-dependent elevation masking in the Bernese GNSS
Software version 5.2. We present our preliminary results on the use of this new feature to
study the impact of different obstruction scenarios on long-term GNSS position time series
and vertical land movement estimates. The results show that a certain obstruction, with the
effect being highly dependent on its severity and azimuthal direction, affects all coordinate
components with the effect being more significant for the Up component. Moreover, it
causes changes in the rate estimates and increases the rate uncertainty with the effect being
site-specific.
Research center :
Institute of Geodesy and Geophysics, University of Luxembourg, Luxembourg;University of Luxembourg: High Performance Computing - ULHPC
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