Studying Permafrost-Wildfire Interactions in the Age of Nisar

Rising air temperatures in the Arctic threaten the stability of permafrost and will result in an increase in the severity and frequency of tundra wildfires. Wildfires can dramatically alter local hydrology, vegetation, topography, and permafrost physical properties and processes, including emission of greenhouse gases. Despite this, permafrost-wildfire interactions remain a poorly understood component of the global carbon cycle. Here, we use interferometric synthetic aperture radar (InSAR) observations to quantify the annual subsidence and deformation rates of seasonally thawing/freezing permafrost across a study region characterized by unburned tundra and tundra recently burned from a series of wildfires in 2015. We propose a method to estimate and remove the component of the interferometric phase measurement due to time-varying soil moisture. We resolve elevated seasonal deformation rates over recently burned tundra in comparison to unburned tundra. Although burned deformation rates tend to revert to unburned values within a decade post-fire, surface soil moisture values within fire scars remain elevated. Lastly, we comment on the unique opportunities that the upcoming NISAR mission will enable to better study permafrost-wildfire interactions.