Frequency dependence of scattering from the cold-temperate transition surface in a polythermal glacier
Article first published online: 28 MAY 2005
Copyright 2005 by the American Geophysical Union.
Volume 40, Issue 3, June 2005
How to Cite
2005), Frequency dependence of scattering from the cold-temperate transition surface in a polythermal glacier, Radio Sci., 40, RS3007, doi:10.1029/2004RS003090.(
- Issue published online: 28 MAY 2005
- Article first published online: 28 MAY 2005
- Manuscript Accepted: 22 FEB 2005
- Manuscript Revised: 17 JAN 2005
- Manuscript Received: 11 MAY 2004
- ground-penetrating radar;
- englacial objects
 Radar surveys of the cold-temperate transition in polythermal glaciers have been used to investigate the polythermal structure, as well as the stability of the temperature regime, in glaciers. The mapping is based on the detection of small water-filled pockets present in the temperate ice beneath the cold surface layer. I compare radar profiles recorded at different frequencies on a polythermal glacier to show that the apparent depth to the cold-temperate transition reflection at a center frequency of 155 MHz is significantly greater than that detected at frequencies above 345 MHz. This increase appears to be the result of a reduction of scattering efficiency from the uppermost part of the temperate ice, as the theory of electromagnetic scattering from small objects indicates a strong decrease in scattering efficiency from objects much smaller than the wavelength of the incident wave. Thus I interpret this apparent depth increase to indicate that the average radii of the water pockets of the cold-temperate transition is on a subdecimeter scale. Spatial variation in the difference between cold-temperate transition depths at 155 MHz and higher frequencies may arise from spatial variations in size or the number density of scatterers.