Permafrost model sensitivity to seasonal climatic changes and extreme events in mountainous regions

Abstract

Climate models project considerable ranges and uncertainties in future climatic changes. To assess the potential impacts of climatic changes on mountain permafrost within these ranges of uncertainty, this study presents a sensitivity analysis using a permafrost process model combined with climate input based on delta-change approaches. Delta values comprise a multitude of coupled air temperature and precipitation changes to analyse long-term, seasonal and seasonal extreme changes on a typical low-ice content mountain permafrost location in the Swiss Alps. The results show that seasonal changes in autumn (SON) have the largest impact on the near-surface permafrost thermal regime in the model, and lowest impacts in winter (DJF). For most of the variability, snow cover duration and timing are the most important factors, whereas maximum snow height only plays a secondary role unless maximum snow heights are very small. At least for the low-ice content site of this study, extreme events have only short-term effects and have less impact on permafrost than long-term air temperature trends.

Large-area land surface simulations in heterogeneous terrain driven by global data sets: application to mountain permafrost

“…At site scales several studies have applied numerical models to investigate the ground thermal regime at specific J. Fiddes et al: Large-area land surface simulation driven by global data permafrost sites (Scherler et al, 2010(Scherler et al, , 2014; however, in a few studies downscaled climate data have been used to force such a model (e.g. Marmy et al, 2013).…”

Soil Moisture Data for the Validation of Permafrost Models Using Direct and Indirect Measurement Approaches at Three Alpine Sites

“…The modeled processes of water infiltration into the frozen soil were implemented and described by Stähli et al (1996) and a complete description and test of water infiltration is given by Scherler et al (2010). The model has already been used in many studies focussing on various purposes, including soil moisture (e.g., Noroozvalashedi et al, 2012;Wu and Jansson, 2013) and permafrost (Engelhardt et al, 2010;Marmy et al, 2013Marmy et al, , 2015Scherler et al, 2013Scherler et al, , 2014Staub et al, 2015). Other studies specifically applied the COUP model to simulate the soil moisture in frozen grounds (Scherler et al, 2010;Xarpell et al, 2010;Python, 2015).…”

“…The active layer thickness (ALT) typically varies between 4 and 6 m with maximum of 8.55 m in 2003(PERMOS, 2013. The possible long term evolution of permafrost at Schilthorn was investigated using the COUP model and downscaled RCM scenarios for the next 100 years (Marmy et al, 2013Scherler et al, 2013). According to these studies, permafrost at Schilthorn is comparatively sensitive and will probably start to degrade early within this century.…”

“…To analyze the water and ice content evolution in detail we used the heat and mass transfer model COUP (see Scherler et al, 2010Scherler et al, , 2013Marmy et al, 2013). Due to the complexity of the coupled hydrological and thermal processes in the ground, we used here the semi-automated calibration scheme proposed by Marmy et al (2015).…”

“…The COUP model is currently used in permafrost research for process modeling and long-term transient modeling of the permafrost evolution (Scherler et al, 2010(Scherler et al, , 2014 as well as for sensitivity studies (Engelhardt et al, 2010;Marmy et al, 2013;Staub et al, 2015), whereas the 4PM was selected for its ability to determine the spatial variability of ice content in the ground, which was found to be one of the key factors controlling the sensitivity of mountain permafrost to climate changes (e.g., Harris et al, 2009;Scherler et al, 2013).…”