Nouvelles

NSERC PermafrostNet news, updates and activities.

Beyond MAGT: learning more from permafrost thermal monitoring data with additional metrics.

Ground temperature is the most common variable in permafrost monitoring and one of three products used to characterize the permafrost Essential Climate Variable by the World Meteorological Organization.

PermafrostNet’s data scientist, Nicholas Brown, has conducted an investigation into the metrics used to assess indicators of permafrost and heat changes in the ground.

Based on this investigation, recommendations are provided for a set of five metrics that offer a more comprehensive picture of permafrost thaw.

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.

The team investigated the behaviour of existing and novel metrics derived from temperature observations (TSP metrics) using an ensemble of more than seventy 120-year simulations. They 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. They also quantified the effect of sensor placement on the magnitude of observed MAGT trends.

Brown, N. and Gruber, S. (2025). Beyond MAGT: learning more from permafrost thermal monitoring data with additional metrics, EGUSphere [preprint], DOI: https://doi.org/10.5194/egusphere-2025-2658

By Tristan MacLean, ago

Modelling the temporal dynamics of subarctic surface temperature inversions from atmospheric reanalysis for producing point-scale multi-decade meteorological time series in mountains

The vertical profile of air temperatures in subarctic regions is difficult to quantify, especially in areas with mountainous terrain subject to strong and lasting inversion events. 

Relying on observational data is not possible in most places due to sparse weather stations.

Une étude récente de Victor Pozsgay tackles the challenge of developing a model that leverages atmospheric reanalysis data and calibrates it using data from five weather stations in the Yukon, Canada.

Map of the study area showing the five sites around Dawson City, Yukon Territory, Canada. The basemap is composed of the Esri World Terrain Base and Esri World Hillshade layers, and is projected in the WGS 1984 Web Mercator projection.

Accurately tracking air temperatures in subarctic mountainous regions is a challenging task, especially due to the prevalence of strong and frequent temperature inversions. These inversions play a critical role in shaping permafrost distribution and regional climate dynamics, yet traditional observations are sparse because of the lack of weather stations in rugged terrain. Victor’s study tackles this challenge by developing a model that leverages atmospheric reanalysis data and calibrates it using actual data from the Yukon. The calibrated model successfully reflects the trends in inversion frequency, strength, and depth that have been evolving since 1948, departing from typical warming patterns seen elsewhere. This approach makes it possible to produce reliable, point-scale meteorological time series for even the most inaccessible locations—an essential advance for studies of permafrost and the broader climate system. The model’s reliance on global reanalysis data and minimal location-specific calibration means it is poised to be both future-proof and widely applicable for regional climate applications, offering a much-needed solution for addressing data gaps in complex, mountainous terrains.

Mean daily pressure-level temperatures for several altitudes at and above the Dawson Airport (ERA5 data on 1 February 2007). The dependence with altitude is linear above 2300 m, where the linear lapse rate can be fitted. Below this, a ‘‘lapse’’ temperature is extrapolated at the grid and station levels. In the grey band, the altitudinal temperature behaviour is inverted, increasing with elevation. The elevation of the five stations used is reported on the right-hand side. The reanalysis data appear in blue, with points representing the pressure level air temperature Tpl and a triangle at the grid level for the surface temperature Tsur. Finally, the observed temperature Tobs is a green diamond at the station’s elevation.

Victor Pozsgay and Stephan Gruber. 2025. Modelling the temporal dynamics of subarctic surface temperature inversions from atmospheric reanalysis for producing point-scale multi-decade meteorological time series in mountains. Arctic Science. 11: 1-16. https://doi.org/10.1139/as-2025-0027

By Tristan MacLean, ago

Seminar – POSTPONED – Tundra Firescape: Vegetation Succession and Perceptions.

POSTPONED – Due to unforeseen circumstances today’s seminar has been postponed.

We will let you know as soon as we have a new date for the seminar.

Thank you for your understanding.

Léa Cornette will be presenting Tundra Firescape : Vegetation Succession and Perceptions.

Please note that the seminar will be presented in French, with slides provided in English.

Veuillez noter que le séminaire sera présenté en français, avec des diapositives en anglais.

Date: POSTPONED
Time: 13:00-14:00 Eastern Time
Location: Zoom (details are posted in our Teams site).

Increased wildfire activity regimes in the Arctic tundra is a growing concern owing to their ecological and human impacts. This study explores the long-term effects of wildfires on soil physical properties, nutrients availability and vegetation succession, using a fire scar chronosequence (EV034-68, EV014-12, EV014-23) in the Inuvialuit Settlement Region (ISR) around Inuvik. Using a mixed approach, this study also aims to understand the perceptions of community members from the ISR of how wildfires, but also weather and climate variations, modify the landscape and their relationship with it.

By Tristan MacLean, ago

Seminar – 16 July – Characterizing carbon and water fluxes in the arctic boreal forest using plant hydraulics parameterization in the presence and absence of permafrost.

Muhammad Umair will be presenting Characterizing carbon and water fluxes in the arctic boreal forest using plant hydraulics parameterization in the presence and absence of permafrost: a modelling approach.

Date: 16 July 2025
Time: 13:00-14:00 Eastern Time
Location: Zoom (details are posted in our Teams site).

Stomatal conductance in terrestrial biosphere models (TBMs) plays a critical role in accurately simulating carbon and water fluxes, and for evaluating the impacts of climate change on land surface-atmosphere interactions. Climate change impacts such as more frequent heat waves and drought conditions challenge TBMs and need to be investigated thoroughly, especially in the rapidly changing arctic boreal forest. Terrestrial biosphere models such as the Canadian Land Surface Scheme Including Biogeochemical Cycles (CLASSIC) often employ empirical formulations that link soil moisture to stomatal conductance. These soil moisture-based empirical approaches typically perform poorly under drought conditions.

Our study implemented an explicit plant hydraulics parameterization in CLASSIC to connect the soil-plant-atmosphere continuum through plant hydraulic traits, i.e., stomatal optimization based on xylem hydraulics (SOX), resulting in CLASSICSOX. Model performance was evaluated at eight arctic boreal forest sites; three are permafrost-free, four are in the discontinuous permafrost zone, and one is in the continuous permafrost zone. Compared to the default CLASSIC, simulated gross primary production (GPP) improved at all eight sites with CLASSICSOX. Drought conditions at the eight sites were identified using the Palmer Drought Severity Index, and the results showed improvement in simulated GPP during drought conditions. Overall, the SOX parameterization achieved improved results compared to CLASSIC by-default at all sites, specifically for the sites located at the continuous and discontinuous permafrost zone.

By Tristan MacLean, ago

Seminar -2 July – Flood Susceptibility Assessment of the Hudson Bay Railway.

Adeleh Moqadam will be presenting Flood Susceptibility Assessment of the Hudson Bay Railway.

Date: 2 July 2025
Time: 13:00-14:00 Eastern Time
Location: Zoom (details are posted in our Teams site).

The Hudson Bay Railway (HBR) is a critical transportation link in northern Manitoba, providing access to the Port of Churchill. Its location across a permafrost region and extensive wetlands poses ongoing drainage challenges, especially under changing climate conditions. Washouts along the railway over the past decade, caused by excessive water flow, have highlighted its vulnerability to flooding events.

In this seminar, Adeleh will present two studies that preliminarily assess flood risk potential along the HBR using GIS analysis and hydrological modeling. The first study involves developing a flood susceptibility map to identify segments of the track that are more prone to flooding. The second study quantifies potential increases in runoff due to climate change at a railway bridge in the Weir River basin, which was previously identified as a highly flood-prone area. This is done by developing a semi-distributed hydrological model using the Raven Hydrological Modelling Framework. After calibrating the model under current climate conditions, it was forced with climate change projections to simulate future peak flows. Findings from these studies aim to support decision-makers in improving the HBR drainage system and enhancing its long-term resilience to climate change.

By Tristan MacLean, ago

Seminar -18 June – Beyond Frozen Ground: Seeing Ground Ice and Terrain Through a Different Lens.

Niek Jesse Speetjens will be presenting Beyond Frozen Ground: Seeing Ground Ice and Terrain Through a Different Lens.

Date: 18 June 2025
Time: 13:00-14:00 Eastern Time
Location: Zoom (details are posted in our Teams site).

Permafrost science spans a wide range of disciplines and landscapes, united by a common goal: understanding the impacts of climate change on sensitive permafrost regions. Yet, there is little consensus on how to classify terrain units with similar responses to change—making cross-disciplinary and cross-study synthesis a persistent challenge. This is further complicated by the multi-scale nature of the processes we study, from fine-resolution field observations to global-scale Earth system models. To meaningfully connect these scales, we need a shared framework that unifies how we view and classify permafrost terrain across scales and disciplines.

By Tristan MacLean, ago

Seminar -11 June – A terrain-based method for snow depth prediction applied in Svalbard, Norway.

Lucas Fuertes will be presenting A terrain-based method for snow depth prediction applied in Svalbard, Norway.

Date: 11 June 2025
Time: 13:00-14:00 Eastern Time
Location: Zoom (details are posted in our Teams site).

Snow is an effective insulator, mediating the effects of climate on the ground thermal regime. Snow is also an important part of the hydrologic cycle, storing and releasing water which influences the functioning of arctic ecosystems as well as energy exchanges with the ground surface. Crucial to both processes are the properties of the snow, topography, and climate, however, models that account for all these variables are data intensive. This presentation suggests a machine learning methodology that leverages terrain-based parameters to estimate snow depths and outlines its applicability in the glacial forefield of Scott Turnerbreen, Svalbard, Norway. Such a model has potential to improve estimates of snow water equivalence across the study site and aid in quantifying the effects of snow on the underlying permafrost.

By Tristan MacLean, ago

Seminar – 21 May – Probabilistic Assessment of Thaw Settlement in Permafrost Terrain Under Climate Change.

Khatereh Roghangar will be presenting Probabilistic Assessment of Thaw Settlement in Permafrost Terrain Under Climate Change.

Date: 21 May 2025
Time: 13:00-14:00 Eastern Time
Location: Zoom (details are posted in our Teams site).

This presentation introduces a probabilistic methodology to assess thaw settlement in permafrost terrain under climate change, addressing the limitations of traditional deterministic models that overlook uncertainties in soil properties and climate projections. Using thermal modeling (TEMP/W) and Monte Carlo simulations, the study developed a custom Python tool to evaluate thaw settlement, serviceability, and optimized maintenance strategies.

Applied to real-world cases, the Hudson Bay Railway and Inuvik to Tuktoyaktuk Highway, the results highlight the growing variability in thaw behaviour over time and the critical role of embankment thickness in performance. By integrating probabilistic analysis into infrastructure design, this work enables more resilient and cost-effective planning for cold regions affected by permafrost degradation.

By Tristan MacLean, ago

Seminar – 14 May – A model of temperature inversions to correct bias in reanalysis data.

Victor Pozsgay will be presenting A model of temperature inversions to correct bias in reanalysis data.

Date: 14 May 2025
Time: 13:00-14:00 Eastern Time
Location: Zoom (details are posted in our Teams site).

The magnitude and frequency of slope failures in permafrost zones have increased in recent decades. Permafrost warming and thawing represent major contributing factors to large slope failures, which have the potential to damage infrastructure and pose a risk to human life and surrounding ecosystems. 

I will present a simulation workflow to generate ensemble simulations of the ground thermal regime at any point globally. The model is driven by reanalysis data, which are known to poorly represent temperature inversions. Hence, I will focus on modelling temperature inversions in sub-arctic valleys where cold-air pooling is particularly intense in cold months. This framework allows for consistent and efficient production and analysis of mountain permafrost simulations in relation to slope failures. However, its main strength and appeal lie in its ability to be used globally and for a large number of sites, efficiently. 

By Tristan MacLean, ago

Seminar – 4 June – Proglacial Retrogressive Thaw Slumping, Svalbard.

Liam Carson will be presenting Proglacial Retrogressive Thaw Slumping, Svalbard.

Date: 4 June 2025
Time: 13:00-14:00 Eastern Time
Location: Zoom (details are posted in our Teams site).

The Arctic is warming rapidly, driving cryospheric changes like glacial retreat and permafrost thaw that transform proglacial landscapes. This study examines ice-cored moraine dynamics in Scott Turnerbreen (STB) and Longyearbreen (LYB) in central Spitsbergen using UAV surveys, satellite imagery, and Ground Penetrating Radar. Since 2018, STB lost 67,350 m³ of material, while LYB lost 115,252 m³, driven by larger Retrogressive Thaw Slumps (RTS). The findings highlight the impacts of ice-cored moraine thaw on geomorphology, sediment release, and hydrology, emphasizing the need for continued monitoring and predictive modelling.

By Tristan MacLean, ago