Active Layer Thickness

Active Layer Thickness (ALT) refers to the top layer of soil that freezes during winter and thaws during summer in Arctic and sub-Arctic regions. It varies seasonally and geographically, influenced by climate, vegetation, and soil properties. ALT is important for understanding permafrost dynamics, as it affects ecosystems, infrastructure stability, and climate change impacts. During warmer periods, the active layer deepens, potentially causing long-term changes in the environment. Measuring ALT helps scientists monitor these changes and assess how climate variability influences thawing permafrost areas.