Special issue  

Permafrost is a widespread phenomenon in the cold regions of the globe and is clearly under-represented in global monitoring networks. Studies of permafrost dynamics are typically conducted through boreholes, which are invasive, expensive, and rarely representative at the field level. Geophysical techniques such as electrical, electromagnetic, and seismic methods have demonstrated their potential as useful non-invasive tools for detecting, mapping, and characterizing permafrost with a spatial and temporal resolution which cannot be achieved using only borehole data. Moreover geophysical surveys are flexible and can be easily adapted to different field conditions and investigation targets. Today, electrical methods such as electrical resistivity tomography (ERT) have been established as standard techniques to gain a general understanding of the subsurface structure at permafrost sites. In addition, there is a growing interest in the development of emerging technologies such as induced polarization methods and environmental seismology as well as joint inversion approaches of multiple datasets to gain a better interpretation of geophysical signatures at permafrost sites. Given their high sensitivity to changes in the ice and water content of the subsurface, repeated surveys, as well as continuous monitoring of geophysical properties, have become popular for monitoring permafrost degradation in both polar and mountain permafrost environments. A dedicated action group of the International Permafrost Association (IPA) has recently been formed to advance an international database for electrical survey data on permafrost (Towards an International Database of Geoelectrical Surveys on Permafrost, IDGSP).

This special issue aims for an overview of current challenges and recent advances in detecting, characterizing, and monitoring the geophysical properties of frozen ground, including advances in survey design and monitoring set‐up, processing and inversion of collected time series, laboratory experiments, and quantification of temporal changes in ground ice content. We welcome applied and theoretical contributions based on all relevant geophysical techniques from polar and mountain permafrost environments as well as laboratory investigations.

Review process: all papers of this special issue underwent the regular interactive peer-review process of The Cryosphere handled by members of the editorial board as well as guest editors designated by the TC co-editors-in-chief.