Which factors affect the thickness of the active layer above permafrost?

The active layer is the surface portion of the ground in permafrost regions that thaws during the summer and freezes during the winter. Its thickness is primarily determined by the following factors:

• Moisture Content: This is the main factor influencing thickness. The active layer is typically thinner (less than a foot) in wet, organic sediments and thicker (several feet) in well-drained gravels.1
• Vegetation: Vegetation acts as an insulating shield that protects the underlying ground from solar energy. The removal or disturbance of this cover can lead to increased thawing of the permafrost, thereby affecting the active layer.2
• Solar Radiation: Topography plays a role, as south-facing slopes receive more incoming solar energy than other areas, making them warmer and influencing the depth of the thaw.2
• Snow Cover: Snow acts as an insulator that influences heat flow between the ground and the atmosphere. Timely snowfall can prevent heat from escaping the ground during winter, which impacts the thermal balance and the subsequent seasonal thaw.2