Name
The Importance of Coarse Blocky Sediments in Permafrost Occurrence in Mountain Environments.
Description
Permafrost is a key component of the cryosphere, influencing energy exchanges, hydrological processes, and natural hazards. In mountainous areas, permafrost occurrence is affected by complex topography and surficial geology, resulting in high spatial heterogeneity. In discontinuous alpine permafrost zones, the lowest-elevation permafrost is typically found in coarse blocky sediments. These surficial sediments create a unique thermal regime that allows permafrost to persist even under positive mean annual air temperatures.
This study investigated the role of coarse blocky sediments in permafrost occurrence in the Canadian Rockies using fieldwork and numerical modeling. Ground surface temperature sensors were deployed at various elevations, ranging from 2000 to 2500 m.a.s.l., revealing that areas with larger sediments had lower ground temperatures than zones with finer sediments. Additionally, an integrated hydrological model (GeoTOP) was modified to improve the prediction of permafrost occurrence in surficial sediments by incorporating temperature-driven air convection in the subsurface energy balance.
The model was tested in the Lake O'Hara basin in the Canadian Rockies, and the results showed that the presence of coarse blocky sediments led to ground temperatures that were four to seven degrees colder when air convection was considered. These results enhance our understanding of permafrost dynamics in mountainous environments and provide a valuable tool for predicting future permafrost extent in response to climate change. Overall, this study highlights the importance of considering surficial geology and air convection when predicting permafrost occurrence and its sensitivity to environmental changes in these types of environments.
This study investigated the role of coarse blocky sediments in permafrost occurrence in the Canadian Rockies using fieldwork and numerical modeling. Ground surface temperature sensors were deployed at various elevations, ranging from 2000 to 2500 m.a.s.l., revealing that areas with larger sediments had lower ground temperatures than zones with finer sediments. Additionally, an integrated hydrological model (GeoTOP) was modified to improve the prediction of permafrost occurrence in surficial sediments by incorporating temperature-driven air convection in the subsurface energy balance.
The model was tested in the Lake O'Hara basin in the Canadian Rockies, and the results showed that the presence of coarse blocky sediments led to ground temperatures that were four to seven degrees colder when air convection was considered. These results enhance our understanding of permafrost dynamics in mountainous environments and provide a valuable tool for predicting future permafrost extent in response to climate change. Overall, this study highlights the importance of considering surficial geology and air convection when predicting permafrost occurrence and its sensitivity to environmental changes in these types of environments.