Dissertation

Passive Radar Sounding for Terrestrial and Planetary Glaciology

Peters, Sean Thomas

2020

Overview

Can ambient radio signals, such as the Sun, be used to monitor the thickness of glaciers? Traditional ice-penetrating radars transmit a powerful electromagnetic pulse and record the echo's delay time and power to measure ice sheet thickness and subsurface conditions. While active radar sounding is the principle remote sensing technique used to observe the subsurface of Greenland and Antarctica, existing radar systems are resource-intensive in terms of cost, power, and logistics when simultaneously monitoring ice sheets at both their evolving temporal (daily to multiannual) and spatial (tributary to continental) scales. However, these observations are critical as ice sheet contribution to sea level rise presents one of the greatest challenges our society faces in the next century. In this dissertation, we address this challenge by developing a novel, low-resource, passive radar sounding technique that uses ambient radio signals from the Sun to observe the subsurface of ice sheets at these spatiotemporal scales, instead of transmitting its own powerful radio signal for echo detection.In this work, we demonstrate for the first time that one can use the Sun as a signal of opportunity to measure ice sheet thickness. Starting from theory, simulation, and lab testing, we first show how one can extract the amplitude and delay time of a received white noise Sun echo. We then describe how this passive radar technique was used to measure ice thickness at Store Glacier, Greenland. We then evaluate the passive radar's performance and ability to provide valuable glaciological observations, such as melt rates, bed reflectivity changes, and englacial water storage-all scientific measurements that have traditionally been obtained using active radar systems but never passively.We then extend this technique to develop a novel passive synthetic aperture radar (SAR) approach that uses astronomical white noise, such as the Sun and Jupiter's radio emissions, as a source for echo detection, ranging, and imaging. We conclude with an analysis of how a passive HF radar could use Jupiter's radio emissions alongside an active VHF radar to correct for the dispersive effects of the ionosphere, estimate Europa's total electron content, and characterize Europa's ionosphere during a flyby mission.

• Publisher: ProQuest Dissertations & Theses
• Subject: Astronomy / Electrical engineering / Emissions / Geometry / Geomorphology / Geophysical engineering / Geophysics / Glaciers / Glaciology / Ice sheets / Ice thickness / Ionosphere / Power / Radar / Receivers & amplifiers / Remote sensing / Sea level rise / Signal processing / Water storage
• ISBN: 9798494461865