University of Alaska Fairbanks researchers have developed a new way to use radar technology to detect open water zones and other changes in frozen rivers in Alaska during the early winter months. This method can be automated to provide hazard maps and is applicable across the Arctic and sub-Arctic regions. Many Alaskans, especially those in rural areas, rely on frozen rivers as ice highways for transportation and recreational activities, making open water zones in river ice a potential hazard.
The research, led by remote sensing scientist Melanie Engram of the Water and Environmental Research Center at UAF Institute of Northern Engineering, was detailed in a paper published in the journal Remote Sensing of Environment. Co-authors include researchers from various UAF departments and centers, as well as the Geophysical Institute. The study focuses on the impact of Arctic warming on river freeze-ups, open water zones, and breakups, which have affected rural winter river travel in Alaska.
The team used synthetic aperture radar data from 12 locations on eight Alaska rivers to create a river ice classification system that can be used in northern high-latitude regions from October through January. This system is designed to provide current open water zone maps and can be tailored for any northern latitude river, not just in Alaska. SAR technology, operating in the microwave portion of the electromagnetic spectrum, can penetrate atmospheric conditions like clouds, haze, fog, and rain, making it ideal for environmental monitoring and disaster management.
The classification system developed by Engram and her team reduces the classification of river ice to four categories: ice, open water, less certain ice, and less certain open water. The researchers worked with two types of radar data, vertical-vertical, and vertical-horizontal, which provide different data features based on the orientation of the returning wave. They compared SAR data with various sources like aerial photos, on-ice observations, reports from community members, shore-based cameras, and observer portal submissions to validate their findings.
The study focused on eight rivers in Alaska with varying characteristics such as volume, width, channel types, and permafrost conditions. By distinguishing between ice and open water, the researchers aimed to provide a more accurate representation of river conditions during the early winter months. The research was funded by NSF’s Navigating the New Arctic and Arctic Observing Network programs, as well as NASA’s Citizen Science for Earth Systems Program. Engram noted the importance of data availability at the Alaska Satellite Facility for making SAR data accessible to scientists worldwide.
Overall, the research conducted by UAF scientists demonstrates the potential of SAR technology in detecting open water zones and changes in frozen rivers, particularly in the early winter months. The study’s findings have implications for improving hazard maps and river ice classification systems in Arctic and sub-Arctic regions, providing valuable information for communities that rely on frozen rivers for winter travel and activities. Additionally, the collaboration between various UAF departments and funding from NSF and NASA highlights the importance of research in understanding the impacts of climate change on Arctic environments.