| 06 Aug 2025
Beyond MAGT: learning more from permafrost thermal monitoring data with additional metrics
Abstract. Metrics such as the mean annual ground temperature (MAGT) and active layer thickness (ALT) are used to monitor and quantify permafrost change. However, these have limitations including those arising from the effects of latent heat, which reduce their sensitivity. We investigated the behaviour of existing and novel metrics derived from temperature observations (TSP metrics) using an ensemble of more than seventy 120-year simulations. We evaluated which TSP metrics provide new insight into permafrost change and evaluated how reliably each one indicates changes in sensible, latent, and total heat contents for different levels of sensor quality. We also quantified the effect of sensor placement on the magnitude of observed MAGT trends.
Based on this, we recommend a parsimonious set of five TSP metrics that provide a better picture of permafrost thaw than MAGT alone. These are: height of the permafrost table (TOP), depth of zero annual amplitude (dza), thermal integral (τ), mean annual ground temperature (MAGT), and mean annual surface temperature (MAGST).
We observed depth-related differences in MAGT warming rates of more than 0.23 °C dec-1 in 50 % of 10-year observation periods for observation depths between 10 m and 20 m. The magnitude of these differences roughly corresponds to the mean warming rate reported for discontinuous permafrost. The effect of sensor depth on warming trends is found to be greatest in ice-poor soils. These results illustrate the challenge of interpreting the magnitude of observed ground temperature trends.
Our results can be used to inform permafrost monitoring strategies and help contextualize observed trends. Consistent metrics can be produced from observed and simulated thermal data via the "tspmetrics" library available on the Python Package Index (PyPi).
Competing interests: SG is the owner of Cryogeeks (13756378 Canada Inc.), which distributes GeoPrecision equipment, referred to in this study for describing sensing systems. The authors declare that they have no other competing interests.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
