Data from Earth observation satellites could help make travel on lake ice safer
In fall 2017, as part of its Earth Observation Applications Development Program (EOADP), the Canadian Space Agency (CSA) issued an Announcement of Opportunity to support research and development on the integration of data from multiple sources. This is defined as the combination of RADARSAT imagery with data from other Earth observation satellites, plus any other complementary forms of data such as on- site measurements and simulations. Twelve Canadian companies will receive a total of more than $1,750,000 in funding.
NextGen Environmental Research Inc., a Winnipeg-based company, will receive just over $127,000 to study pressure ridges in lake ice. If successful, this research would eventually lead to the creation of maps that would show where this type of hazard in lake ice occurs. These maps would be an invaluable tool for many people, aiding with travel routing during winter and reducing risk in early spring.
Using – data from the RADARSAT-2 and Sentinel-1 synthetic aperture radar (SAR) satellites and a fixed-wing drone, NextGen studied the ice cover on 84 lakes, including a complex ice cover on Lake Winnipeg. The funding provided by the EOADP enabled a comprehensive study that identified radar image values from pressure ridges, rubble ice, and the surrounding ice types in winter and spring.
"Using SAR image values, we recorded important changes in the stages of ice development and decay, and the differences between daytime, when it is melting, and nighttime, when it's freezing. Understanding the SAR image data for the entire ice period is key to monitoring lake ice hazards in a warming climate. These innovations in Canada's remote sensing sector may decrease the risks posed by lake ice hazards. We also anticipate an increase in climate resilience for remote communities that travel over lake ice and for a growing number of recreational users."
Canada has the largest number of seasonally frozen lakes of any country in the world. Some lakes are located close to major urban centres and used by many people for winter recreation, such as ice fishing. Other lakes are tucked away in remote areas but provide important travel routes for commercial fishers, First Nations, and northern communities. Travel on lake ice in Canada is common for commercial activities and income. Still, many Canadians lack knowledge of lake ice, and of the ice features that reveal the early warning signs of decay – and danger – in the spring.
For lake ice, the first hazards in the spring develop along pressure ridges, leads, and cracks as open water becomes exposed. Pressure ridges can be over two metres tall and can extend across large lakes (over 50 km). They form a barrier to travel whether on foot or in any type of surface vehicle. Cracks can also create open water when the horizontal ice sheet shrinks during cold periods. Overnight, thin ice can form in the crack and become covered in snow, creating an unseen hazard for motor vehicles.
The NextGen project began in February 2018. Its intent is to show that satellite data can be used to map ridges over large areas. In the south basin of Lake Winnipeg, NextGen compared 14 RADARSAT-2 images with optical satellite and drone data from winter to just prior to ice break-up. Integration of radar and optical satellite data and very high-resolution drone data is key to document the processes of pressure ridge growth and decay and to select the best approach for satellite mapping in the future. If successful, this project will demonstrate that Canada has developed a novel capacity to aid with mapping of travel routes in winter and help identify potential lake ice hazards in early spring at home and abroad.
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