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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
5. CONCLUSIONS
This paper has shown examples of satellite- and ground-based
stereo analysis of clouds. Regarding satellites, there are various
sensors currently available which can be used for stereo-
photogrammetric cloud retrievals. For stereo CTHs from a
single polar-orbiter with only two viewing angles (e.g. ATSR2),
it has been proven to be absolutely necessary to correct the
preliminary heights with cloud-top wind (CTW) data from
another source. Over land and mountainous regions, the cloud
motion is most accurately derived from simultaneous images of
a geostationary satellite. Over Europe, the Meteosat-6 Rapid
Scan trials in 1999 (5min) and in 2000 (10min), and the
operational Meteosat-6 10min Rapid Scans (since September
2001) are perfectly suited for this objective. The MISR
instrument and its products were presented as a promising
alternative to derive CTH and CTW simultaneously with stereo-
photogrammetric methods. The images from our new ground-
based imager system showed to be valuable for validation of
vertically thin cloud situations and for combination with
satellite-based cloud boundaries to derive 3D cloud fields which
can then be used for assimilation into numerical weather
prediction and climate models.
In co-operation with Eumetsat, Free University of Berlin and
RAL, the validation activities for satellite-based cloud height
products will be continued. In addition to the geostationary
satellites from the Meteosat First Generation (MFG), the data
from Meteosat-8 will be used for CTW extraction and
eventually stereo cloud-top height estimation in combination
with Meteosat-5.
The ground-based photogrammetric validation activities will be
continued with a stereo set-up of two operational Whole Sky
Imagers at the ARM-SGP site, next to cloud radars. ceilometers
and a Raman lidar.
ACKNOWLEDGEMENTS
The Meteosat-6/-7 data were received from the EUMETSAT
Archive Facility (MARF), the ATSR2 data via the ESA ATSR2
NRT service, the AATSR data from the Rutherford Appleton
Laboratory (RAL) and the EOS-Terra MISR data (level 1B2
and level 2TC) were obtained from the NASA Langley
Research Center Atmospheric Sciences Data Center. This work
is funded by the Bundesamt für Bildung und Wissenschaft
(BBW) within the EU-projects CLOUDMAP (BBW Nr.
97.0370) and CLOUDMAP2 (BBW Nr. 00.0355-1) and by
EUMETSAT within ITT-03/527.
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