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https://hdl.handle.net/11681/2676| Title: | Radar profiling of ice thickness |
| Authors: | Arcone, Steven A. |
| Keywords: | Radar Radar profiling Ice Ice thickness Measurement |
| Publisher: | Cold Regions Research and Engineering Laboratory (U.S.) Engineer Research and Development Center (U.S.) |
| Series/Report no.: | Cold regions technical digest ; no. 85-1. |
| Description: | Technical Digest Introduction: Large-scale profiling of the thickness of freshwater and sea ice is important for understanding the dynamics of a sea ice cover, interpreting satellite microwave imagery, and predicting air-sea heat exchange or the bearing capacity of an ice cover. A practical approach to thickness sensing would be to use a remote ranging system that sends and receives a pulse of energy that reflects from the bottom of the ice. The time of flight of the pulse would then be calibrated to ice thickness. Acoustic (sonar) systems are not well suited because sound couples inefficiently from air to solids. Resolution would thus be poor unless ultrasonic frequencies were used, in which case too much sound energy would scatter in all directions from ice cracks. Electromagnetic (EM or radiowave) systems are better suited because the energy does couple well from air into non-conducting solids such as ice. Additionally, EM pulses can be made short enough for good resolution without worrying about scattering. In the late 1960s radar systems were designed that were capable of probing below the ground surface with extremely short bursts of energy. Commercial systems, known usually as ground-probing impulse radars, may obtain geological information to depths of up to 10m in some soils, up to 15m in fresh water, and up to at least 100 m in good dielectric insulators such as glacial ice. A dielectric insulator like glass, plastic or ice does not conduct electricity but does let waves propagate. Conductive materials like metal, salt water and wet clay convert wave energy into electric currents and are therefore highly absorbing. As with many other geophysical exploration systems, radar data are interpreted most easily where the ground is composed of even, flat layers. Consequently, radar can provide an excellent (although sometimes boring) profile of ice thickness. Where layering breaks up, radar data can be extremely complicated. But if the spatial length of the energy burst is about the same size as or smaller than the radius of curvature of the subsurface unevenness, chances are excellent that the impulse radar echoes will track the irregularities with good precision. |
| Rights: | Approved for public release; distribution is unlimited. |
| URI: | http://hdl.handle.net/11681/2676 |
| Appears in Collections: | Technical Digest |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| CRREL-TD-85-1.pdf | 3.37 MB | Adobe PDF |  View/Open |