Our test sites were chosen to minimize vegetation cover that would interfere with satellitemeasurement of the land-surface temperature, but in practical applications, vegetation cover and snow may hinder the availability of remotely sensed LST for this approach. Small-scale variations in surface composition and topographic conditions create different thermal components that are integrated over large areas for products with moderate spatial resolution, such as MODIS LST. Thermal-infrared sensors with higher spatial resolution, such as ASTER and ECOSTRESS, can be used to resolve the 100-m-scale horizontal changes in the extent of seasonally frozen ground and permafrost. Numerical modeling of the thermal regime of the ground using these surface temperature records may be useful to estimate the depth of thaw in ice-rich frozen grounds and permafrost.