Dual frequency radar ice and snow signatures

Dual frequency (X-band and L-band) synthetic aperture radar imagery of sea ice is examined to show the differences between the bands and their complementary nature for resolving ambiguities in interpretation. High backscatter at X-band from visibly smooth thin ice is not observed at L-band. The hypothesis is that the high X-band backscatter is caused by a reflective layer at the snow/ice interface. A second hypothesis is that the high X-band backscatter may be caused by moisture in the snow. High backscatter at L-band is observed for slush on open water. The return is very weak at X-band, thus allowing distinction of sluch by comparing L-band and X-band images. High intensity, but only partial returns from icebergs at L-band have been observed. The hypothesis is that internal iceberg/sea water reflections are occurring. Some signals are directed away from the antenna; other reinforced signals are returned, producing very bright images. Occasionally, the time-delayed signals are returned causing a false image at far range from the iceberg. The conclusion is that L-band is a poor choice for studies of iceberg distribution and size, but a good choice for studies of iceberg detection because of the high reinforced returns from many icebergs and the low return from the adjacent sea ice. The penetration and subsequent signal loss of L-band in glacial ice, when compared to high X-band returns, may be useful to map glaciated land masses.