Testing the Feasibility of Orbital Altitude Radar Sounding using a Multi-frequency Radar System
Abstract
Radar sounding, used to measure the subsurface layers of ice sheet, has applications ranging from mapping paleoclimate conditions to predicting future sea level rise. Orbital radar sounders have been used to image the subsurface of the Martian polar ice caps, but similar instruments have not been tested on Earth, in part because of the higher frequencies needed to penetrate the Earth's ionosphere. Airborne radar sounding studies suggest that at these higher frequencies and altitudes, there is an increase in clutter from irregular topography on the ice sheet's surface and irregular densities in its firn layers, which interferes with the subsurface signals of interest. In order to evaluate the impact of surface and near-surface clutter on orbital sounder performance, we need to first measure these phenomena at a variety of altitudes and sounding frequencies.
To isolate the variables of altitude and frequency, we are developing a multi-frequency radar sounder attached as a payload to a weather balloon. A weather balloon can reach up to 30km in altitude, where the clutter geometry is modeled to be similar to that at orbital altitudes. Here we present the instrument design, including radar system parameters, link budget, and the payload and balloon engineering required to perform at the temperatures and pressures associated with this altitude. Using electromagnetic models, we also show that for this system the character of the received waveforms is distinctly different depending on the presence and source of clutter. Therefore, by comparing our experimental data with these models, we will be able to determine the relevant clutter regime. Ultimately, this system will inform the design of an orbital sounder and a high altitude drone sounder by determining which frequencies minimize surface and near-surface clutter.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNS13A..02A
- Keywords:
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- 0702 Permafrost;
- CRYOSPHERE;
- 0738 Ice;
- CRYOSPHERE;
- 0758 Remote sensing;
- CRYOSPHERE;
- 0794 Instruments and techniques;
- CRYOSPHERE