Showing papers by "Helmut Rott published in 1991"

Multi-Parameter Airborne Sar Experiments at an Alpine Test Site

Abstract: The high Alpine test site &tal in the Central Alps of Austria was surveyed by the 3-frequency (P-, L-, C-band) polarimetric SAR of JPL on board the NASA DC-8 in August 1989 and by the E-SAR of the German Aerospace Research Establishment in July 1990. The E-SAR was mounted on a small twin-engined aircraft and operated alternately in the Xband and the C-band, HH polarizations, on successive overflights. This data set is the basis for development of data analysis algorithms and application studies in snow hydrology, glaciology, and geomorphology and for the development of radargrammetric methods in complex terrain. Characteristic polarization signatures have been identified for the main surface types such as snow, glacier ice, and ground moraine, revealing significant potential for target discrimination. In case of unpolarized SAR, Cand X-band frequencies enable clear separation of snow cover, glacier ice, and ice free surfaces. Due to differences in the frequency behaviour of backscattering, dual-frequency SAR data are very useful for classification of these targets.

Snow and glacier mapping with polarimetric SAR

Abstract: The objective of this study was to examine the capability of mapping snow and glaciers in alpine regions using synthetic aperture radar (SAR) imagery when topographic information is not available. The topographic effects on the received power for a resolution cell can be explained by the change in illumination area and incidence angle in a slant-rante representation of SAR imagery. The specific polarization signatures and phase difference between HH and VV components are relatively independent of the illuminated are, and the incidence angle has only a small effect on these parameters. They provide a suitable measurement data set for snow and glacier mapping in a high-relief area. The results show that the C-band images of the enhancement factor, the phase difference between HH and VV scattering components, and the normalized cross product of VV scattering elements provide the capability to discriminate among snow with different wetnesses, glaciers, and rocky regions.