MRI: Development of a High-power, Large Antenna Array and Ultrawideband Radar for a Basler for Sounding and Imaging of Fast-flowing Glaciers and Mapping Internal Layers

This MRI award supports the development of radar instrumentation for fine-resolution measurements on polar ice sheets to enable a wide range of scientific investigations. Specifically, a high-power, ultra- wideband, large-antenna multi-channel coherent radar, and an active target/multistatic receiver (ATMR) will be developed. The ultra-wideband radar will operate over the frequency range of 150-600 MHz with a large cross-track array of 24-36 elements. The large cross-track array is required to sound ice in ice-sheet margins and fast-flowing glaciers with very rough surfaces. Radar sounding of ice in these areas is extremely challenging because of surface clutter - off-vertical backscattered signals produced by the rough ice surface - and this can mask weak echoes from the ice bed. The cross-track array is required to reduce this surface clutter to measure ice thickness and characterize conditions at the ice bed, to include whether or not ice is frozen to the bed or sliding on a film of water. The presence of water lubricates the ice bed and that results in ice moving much faster. The ATMR is used to calibrate radars and measure ice loss to estimate conditions at the bed. Existing models can simulate long-term and large-scale evolution of ice sheets, but they are incapable of simulating and predicting short-term and rapid fluctuations observed with satellite sensors. This is mainly because the physics of the underlying processes causing short-term fluctuations are poorly understood and represented in these models. Also the lack of critical information on boundary conditions at the required resolution has been a serious impediment to developing next-generation ice sheet models for simulating observed changes and predicting future response in a warming climate. Bed topography, estimated from ice thickness and surface elevation measurements, and basal conditions are required to predict the response of polar ice sheets in a warming climate using improved ice-sheet models currently in development. Modeling experiments or simulations will be performed to determine the optimum resolution required to characterize fast flowing glaciers and margins. The instrumentation will be designed to meet these requirements. Additionally, the ultrawideband radar will facilitate the process of selecting optimum site for deep core drilling by enabling fine-resolution imaging of the ice-bed interface and mapping internal layers from the surface to the bed, so the choice of ice core drill sites will be more precisely determined. The intellectual merit of this MRI project is the development and deployment of new ultra-wideband radar technology that will contribute to our understanding of key ice sheet processes in rapidly changing outlet glacier regions, ensure successful site selection for a deep-ice core with a climate record of more than a million years, and enable successful mapping of hydrological networks within and under the ice. The broader impacts of this project involve: application of the developed technology to other geophysical studies, including measurements over sea ice and permafrost and measurements of soil moisture, vegetation, and snow thickness over land; involvement of undergraduate and graduate students; partnerships with industry; and three international collaborations. The project will contribute significantly to the training of next generation of scientists by integrating graduate and undergraduate students with the technology and instrumentation development, field observations, and scientific analysis. Broad international partnerships provide unique opportunities for U.S. faculty, staff and students to participate in truly globalized research. This project also includes an industry partnership with Google Inc., which is providing matching support for an airborne camera system and student training in the use of the camera. Images collected along with the corresponding radar results of ice-bed topography will be made available to the public through Google Earth and Google Maps.