Development of an airborne multi-channel FMCW radar for high-resolution mapping of internal layers in glacial ice.

摘要

Global climate change and its associated sea level rise are major environmental issues. Sea level rise has direct impact on the economic and social front of the world. The contribution of melting of polar ice sheets to sea level rise has been a topic of much debate and speculation. Accurate information on the mass balance of polar ice sheet is needed to assess the contribution of polar ice sheets to the rising sea level. Accumulation rate of snow in polar regions is a key parameter in determining the mass balance of polar ice sheets. Accumulation radar developed at KU has been successful in mapping the internal layers of Greenland ice sheet over the dry snow region, where the surface is relatively smooth. Receive diversity is needed to map better the internal layers over the wet snow zone, where the relatively rough surface may cause large clutter that can mask the weak reflections, thereby reducing the accuracy with which an internal layer can be identified. A multi-channel FMCW radar over 600--900 MHz was developed to enable data collection over wet snow and percolation zone. The radar can support up to 16 receivers depending on the region of operation. The entire radar system is significantly miniaturized and fits inside multiple CPCI chassis and is lightweight. Simulation and modeling techniques were used to derive the radar parameters and to optimize the radar performance. The radar is yet to be field-tested, but laboratory measurements have demonstrated that it meets or exceeds all of the design requirements. Simulated results and laboratory measurements in conjunction with a fiber-optic delay-line are used to document the radar's performance.