Description

Permafrost is defined as ground which remains at or below 0°C isotherm for at least two years. It encompasses the perennially frozen ground surrounded by a cryopeg, i.e. a ground layer in which water remains unfrozen at sub-zero temperatures. Furthermore, “dry” permafrost results when water is absent.

Permafrost originates from the ground surface depending on a complex heat exchange process across the atmosphere/ ground boundary layers and on an almost time-invariant geothermal heat flow from the Earth’s interior due largely to radioactive decay of long-lived isotopes of uranium (U), thorium (Th) and potassium (K).

SKB Number

SKB FEP Number

Cli05

Main Category

Main category for FEP

External factor

Sub-category

Sub-category for FEP

Climatic processes and effects

Handling

Explanation of how the FEP is treated

The evolution of permafrost is investigated by means of numerical modelling. The results were used to construct parts of the SR-Site reference glacial cycle. Two numerical permafrost models were used, a 1D model that was used for simulations of permafrost at the repository location, and a 2D model that investigated spatial development of permafrost along a profile that crossed the repository site. The permafrost models include a mathematical expression for freezing and thawing of saline-groundwater-saturated bedrock.

References

Bibliographic references to obtain more information

SR-Site Climate report, TR-10-49, Section(s) 3.4