Estimating Permafrost Distribution Using Co-Located Temperature and Electrical Resistivity Measurements

Assessing the lateral and vertical extent of permafrost is critical to understanding the fate of Arctic ecosystems under climate change. Yet, direct measurements of permafrost distribution and temperature are often limited to a small number of borehole locations. Here, we assess the use of co-located shallow temperature and electrical resistivity tomography (ERT) measurements to estimate at high-resolution the distribution of permafrost in three watersheds underlain by discontinuous permafrost. Synthetic modeling shows that co-located temperature and ERT measurements allow for supervised classification schemes that provide 60% higher accuracy compared to unsupervised methods. Linking resistivity and size of the identified permafrost bodies to surface observations, we show that tall vegetation (>0.5 m) and gentle slopes (<15 degrees) are related to warmer and smaller permafrost bodies, and a more frequent occurrence of taliks. Plain Language Summary To better understand how the Arctic may be changing due to climate warming, we need to understand the distribution of permafrost in the subsurface. Although the temperatures of the ground can be measured in boreholes, only a small number of boreholes exist to do these measurements. Here, we use machine learning to link measurements of temperature and of the electrical resistivity of the ground to obtain detailed distributions of permafrost in the subsurface. Connecting the properties of permafrost with observations above ground, we show that south facing slopes, tall vegetation, and gentle slopes relate to warmer and smaller permafrost bodies.

Automated summary

Assessing the extent of permafrost is crucial for understanding the impact of climate change on Arctic ecosystems. This study proposes a new method that combines temperature and electrical resistivity measurements to estimate the distribution of permafrost. The results show that certain vegetation and slope characteristics are associated with warmer and smaller permafrost bodies, as well as a higher occurrence of taliks.