Summary
A directional anisotropy is observed in backscatter from the surface of the East Antarctic ice sheet as measured by the C-band wind scatterometer carried by the ERS-1 satellite. The anisotropy is characterised by the amplitude of the variation with azimuth of the backscatter coefficient, and an orientation given by the antenna, look direction for minimum backscatter. These data are compared with field observations of surface roughness defined by the frequency of occurrence and orientation of surface microrelief in the form of snow dunes, and sastrugi of various sizes, which are produced by the surface wind. The field data were collected along the traverse route from near the coast (69.03°S, 40.06°E, 591 m a.s.l.) to Dome Fuji (77.31°S, 39.66°E, 3810 m a.s.l.) in east Queen Maud Land. In the katabatic wind region from 2000 m to 3600 m in elevation, the amplitude of the directional anisotropy along the traverse route is consistent with the total frequency of occurrence of sur fa c e microrelief and the low variability in the orientation of those features. A weaker anisotropy in the backscatter is observed about the inland dome area above 3600 m elevation (anisotropy amplitude less than 2 dB compared to values up to 4.5 dB elsewhere). This is associated with both a lower frequency of occurrence of surface microrelief and greater variability in the orientation of the microrelief. The amplitude of the directional anisotropy appears to exhibit the strongest association with the frequency of surface microrelief with larger scale and of ridged shape such as sastrugi.