| Abstract |
Global Navigation Satellite Systems (GNSS) are nowadays
one of the most important geodetic measurement techniques for establishing
the terrestrial reference system and for many Earth observation
applications. Since processes in the Earth system are happening in
time scales from extremely short (earthquakes, volcano eruptions,
land slides, ...) to very long (melting of ice sheets, sea level
change, plate tectonics, ...), global monitoring and early warning systems
must allow, on the one hand, the detection and quantification of catastrophic events
in (near) real-time and, on the other hand, the reliable identification
of barely noticeable, but crucial long-term trends (e.g. sea level
rise) from long data series.
In this contribution we will present the impressive accuracy of GNSS
but also some of its limitations and how to possibly overcome them.
Some of the examples we will look into are measuring earthquakes
(GNSS seismology), determining water vapor and snow coverage, and reducing
GNSS orbit modeling deficiencies (e.g. due to solar radiation pressure)
using the best clocks available in space.
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