The active layer of permafrost which freezes and thaws is seasonally monitored using ground-penetrating radar (GPR) for variation in activity and thickness, especially in response to recent climate change. Ryazantsev wanted to find out whether GPR can provide useful information about thermal factors such as soil temperature change, thermal insulation and thermal conductivity.

Remote sensing is used to help measure carbon and other greenhouse gas emissions and moisture content, however Ryazantsev mentioned there are logistical challenges affecting use. He suggests GPR can be used for remote detection of seasonal freezing and thawing.

They chose three sub-arctic sites with palsa mires on the Kola peninsula, measuring in June & July of 2023 and 2024. They started with lab analysis, then took field measurements and finally used GPR. They noted that variation in permafrost moisture and vegetation cover can affect GPR signalling and detection.

They found that GPR shows useful potential for collecting and monitoring thermal gradients within peatlands, during seasonal permafrost freezing and thawing cycles (FTC). For example gradients of at least ±1 °C as part of peat transition layers evolving during FTC, but GPR responses are affected by thermal variation in peatland environments. They have detected the thermal-hydraulic behaviour of peat including with substantial water changes during FTC which can help with future shallow permafrost mapping.

However for future monitoring accuracy, Ryazantsev recommends additional research with high resolution field studies, controlled GPR experiments and using advanced data methods and technologies for data analysis.

Ryazantsev, P. (2025). Can Ground-Penetrating Radar Detect Thermal Gradients in the Active Layer of Frozen Peatlands? Remote Sensing, 17(11), 1805. https://doi.org/10.3390/rs17111805