Detection of overflow using Synthetic Aperture Radar

Abstract

Overflow is a common and dangerous ice condition that challenges travel, presents risks to people, and impacts the growth and structure of ice. Overflow occurs due to ice cracking and water seeping through. The resulting water and slush from flooded snow that overlies the ice cover can complicate all modes of travel (e.g., snow machines, dog sled teams, skiing, on foot) and introduce the hazards associated with getting wet and stuck amid the cold air temperatures of winter. Synthetic Aperture Radar (SAR) bounces microwave signals off the Earth’s surface to detect physical properties and is not affected by cloudy or dark conditions. Overflow detection with SAR is a novel application of this technology that would enhance historical and present ice monitoring and modeling to ultimately improve traveler safety. This study was conducted to test SAR capability to detect overflow based on our ground-based observation. This study initiates overflow exploration in arctic research and advances SAR as a tool for overflow detection. We determined seasonal changes and ice characteristics through field observations, in situ sensors, and ice models. We found a significant decrease in backscatter intensity during a December overflow event in both bands, with VH decreasing from -17.6 dB to -18.8 dB. Backscatter intensity gradually increased throughout winter until a March overflow event which exhibited only marginal declines in backscatter. Our results of a rapid decrease in backscatter in connection to ground data indicate successful overflow detection. SAR technology paired with ground investigation advances historical investigation and future remote sensing developments specific to overflow, ultimately improving winter travel safety and initiating more scientific information about overflow.