Summary and Future Chances - GNSS Remote Sensing: Theory, Methods and Applications - page 264

high winds, dangerous sea states, risk of flooding, ocean eddy and storm surges.
Furthermore, high-sampling ocean surface roughness will be estimated from future
denser GNSS reflected signals, which may improve our understanding of the air-sea
exchanges, the floe ridges, frost flowers, broken ice, and fine-scale roughness at the
snow-ice interface, particularly for inaccessible and atrocious sea ice cover.
Also the GNSS reflectometry together with ground observation networks of
seismology and geodesy are expected to be applied in a geohazard warning system.
The German Indonesian tsunami early warning system for the Indian Ocean was
established after the Sumatra earthquake of December 2004 ( www.gitews.de ) . It
will later be extended to the Mediterranean and the Atlantic Ocean using new space-
based GNSS reflectometry and scatterometry with all available signal sources,
including the modernized GPS, the restored GLONASS, the establishing Galileo
and the upcoming Compass GNSS. Moreover, future GNSS reflected signals may
be used to monitor crustal deformation, like Synthetic Aperture Radar (SAR), and
GNSS reflectometry is expected to observe the global-scale geodynamic processes
together with other sensors.

12.3 Summary

The refracted, reflected and scattered GNSS signals have been used as a remote
sensing tool in the atmosphere, ocean, land, hydrology and cryosphere. With
continuously increasing global permanent IGS stations and regional continuous
GNSS stations and more satellite constellations of the future multi-frequency
GNSS and Space Based Augmentation Systems, such as GPS, GLONASS, Galileo,
Beidou/COMPASS, QZSS and IRNSS, the denser ground GNSS stations can
receive more multi-path signals and line of sight signals of GNSS satellites through
the atmosphere and ionosphere. It can monitor more detailed ground surface
characteristics and processes and evolutions of the atmospheric and ionospheric
profiles at global and regional scales.
With more and more space-borne GPS reflectometry and refractometry missions
in the near future (e.g., follow-on FORMOSAT-7/COSMIC-2 mission, CICERO
and TechDemoSat-1), these missions will monitor more detailed Earth's surface
characteristics and atmospheric and ionospheric information with high temporal-
spatial resolutions (Jin et al. 2011 ). Furthermore, some advanced GNSS receivers
are being developed with improved algorithms for the various possible applications
and quasi real-time data processing capabilities to satisfy the future space-based
high-performance missions (e.g., next generation TriG (Tri-GNSS) receiver with
the ability to generate multi-GNSS refraction and reflection). It is also possible in
the next few years a low cost instrument will be made public capable of operating
on limited resource satellites, such as those being developed by Universities. New
remote sensing applications using GNSS signals are expected to continue expanding
over a global scale in the coming years.