active layer

American  

noun

1. (in Arctic or subarctic regions) the layer of soil, above the permafrost, that thaws during the summer.

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Example Sentences

This model estimates key processes such as snow accumulation, melt, and changes in the active layer to better represent real conditions.

From Science Daily • Apr. 4, 2026

"A thicker active layer creates a bigger bucket for storing water," says Rawlins.

From Science Daily • Mar. 5, 2024

Permafrost still covers 85 percent of the state, but “almost everywhere, the depth of the active layer is increasing over the last few decades,” said Thoman.

From Slate • Mar. 11, 2015

Increased phase separation and crystallization have a profound effect on the photophysical and transport properties of the active layer.

From Nature • Aug. 15, 2012

Because the frozen permafrost was just a half meter beneath the active layer of soil, all the water on the tundra stayed near the surface.

From "Two Degrees" by Alan Gratz