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Infrared thermography is independent of light conditions but very
sensitive to fog, clouds and any type of precipitation, which often
confines the useable maximum flight altitudes and thus reduces the
mapping capacity.
5.1.6 Satellite information
The information from LANDSAT-2 was of very good quality. The
resolution was about 80 m which made it possible to identify different
ice parameters, such as large ice floes and leads. The areal coverage
was good enabling large-scale mapping for e.g. ice forecasting.
There were, however, severe restrictions in the availability of the
LANDSAT information. It was obtainable only 2-3 times every 18th
day and only on request from NASA. The information was recorded on
amgnetic tape on board the satellite and tapped when passing a
receiving station. One further drawback of the satellites then
used was the weather dependence and, as concerns the visual part,
also the light dependence.
The LANDSAT-2 provided information from four spectral channels
(MSS) in the visual part of the electromagnetic spectrum. The MSS
data gave the best information on ice concentration.
5.1.7 Conclusions
None of the tested sensors alone gave satisfactory mapping of all
the ice parameters required. The FLAR and ODAR gave a general view
of the ice fields, identifying major ice/water boundaries as vell
as major areas of deformed ice.
The SLAR gave much more details about the deformed ice fields and
also identified more leads and fractures. Though it was not possible
by any of the radars to distinguish open water from level ice
directly from the graytones in the imagec, it appeared that open
water areas could be located indirectly in SLAR pictures on the
basis of location, shape; size and sharpness of edges.
All the radar systems had a good areal coverage.