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08.04.2014 18:01

Sentinel-1A and the Remote Sensing Laboratories at UZH

The radar satellite Sentinel-1A was launched on April 3 into low Earth orbit. The UZH's RSL is involved in calibrating and verifying the geometric performance of the radar products generated by ESA's ground segment.


Source: http://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Sentinel-1/Facts_and_figures

David Small, senior research scientist at RSL, is a member of the
Sentinel-1 Mission Advisory Group (MAG). The MAG advises ESA on
developments relevant to the Sentinel-1 mission and is composed of
key scientists working in the fields relevant to Sentinel-1.

Sentinel-1A, the first of two radar satellites from the European Space
Agency was launched into low Earth orbit on a Soyuz rocket on Thursday
April 3.  The C-band radar satellite sees through cloud cover, and will
monitor the Earth's ocean and land surfaces reliably, during both day
and night.  Its three radar imaging modes will be able to provide images
recorded in two polarisations, each at 5m, 20m, or 40m spatial
resolution, with swath widths of <100km, 250km, or 400km respectively.
 Most data will be acquired in the 20m/250km "interferometric wide
swath" mode.

Over oceans, oil spills will be detected and reported to responsible
authorities within minutes.  A specialised "wave mode" will monitor wind
speeds and directions, feeding these measurements into meteorological
models such as those at the European Centre for Medium-range Weather
Forecasts (ECMWF).  The positions of large ships in the northern
Atlantic and Mediterranean will be monitored by the European Maritime
Safety Agency (EMSA).

On land surfaces, multiple Sentinel-1A (S1A) data takes will be combined
using techniques such as synthetic aperture radar interferometry (InSAR)
to monitor surface displacements (earthquakes, volcanoes, subsidence).
 Regular image acquisitions will enable the tracking of glacier and
ice-sheet movements over large areas with unprecedented resolution in
the time dimension.  Although other radar satellites can deliver higher
/spatial/ resolution, Sentinel-1 will acquire images of the Earth's
surface with a revolutionary /temporal/ resolution (revisit interval).

The Remote Sensing Laboratories (RSL) in the Dept. of Geography of the
University of Zurich have been tasked by ESA as an expert support
laboratory (ESL) to help calibrate and verify the geometric performance
of the radar products generated by ESA's ground segment.  We have
deployed corner reflectors that provide an extremely bright radar
signature at well-known surveyed locations in Switzerland to support
this work.  New types of radar products are being developed at RSL to
take advantage of the high temporal resolution, e.g. to map the
progression of melting snow in the Alps in the springtime.  They
correct for the effects of topography on the geometry and radiometry
of the radar data, producing higher level products that can be more
readily interpreted and compared with data from other sources.

Once Sentinel-1A is joined by its companion Sentinel-1B in 2015, the
orbital repeat interval will become 6 days.  When inconstant viewing
angles are integrated, revisit intervals over Switzerland of less than 2
days should be possible.  Further satellites in the Copernicus series
(Sentinel-2A, and -3A) will follow in the coming year with instruments
that operate at visible and infrared wavelengths.


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