Permafrost Thaw Patterning Through Thermal Channelization

Abstract On some frozen hillslopes, subsurface water above permafrost is routed through regularly spaced, linear features known as water tracks, which are active sources of greenhouse gas release. We test whether water tracks form through thermal channelization, where heat from viscous dissipation in flowpaths deepens the thaw, creating a preferred flow path that attracts more water. We derive equations for suprapermafrost Darcy flow—that occurring in unfrozen ground (the active layer) above perennially frozen soil. Using linear stability analysis, we calculate growth rates and obtain wavelength selection for this system, which we compare to observed water track spacing from the Low Arctic. Our model predictions are sensitive to flow speed, but the predicted cross‐slope water track patterns are consistent with observed water track spacing under high flow conditions in the Low Arctic. Our analysis implies that signatures of a warming, wetter climate may be found in reduced inter‐track spacing and increasing water track extent.