Meltwater infiltration into the frozen active layer at an alpine permafrost site

Abstract

A coupled heat and mass transfer model simulating mass and energy balance of the soil-snow-atmosphere boundary layer was applied to simulate ground temperatures, together with water and ice content evolution, in the active layer of an alpine permafrost site on Schilthorn, Swiss Alps. Abrupt shifts and subsequent fluctuations in ground temperature observed in alpine permafrost boreholes at the beginning of the zero curtain phase in summer were explained by snowmelt and meltwater infiltration. Simulated water contents were compared to values derived from inverted electrical resistivity measurements and yielded a further independent validation of the model results. The study shows that infiltration into frozen soil takes place as an oscillating process in the model. This process is constrained by initial ground temperatures, infiltrability and the availability of meltwater from the snow cover.

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

“…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 model has already shown good ability to simulate ground temperature regimes, precise snow conditions and soil moisture.…”

“…Under supersaturated conditions, the flow of water is accumulated upwards in the upper soil compartment until it reaches the surface and leaves the system with the surface runoff. 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).…”

“…Furthermore, the in situ soil moisture measurements necessary for the validation of remote sensing products (e.g., Albergel et al, 2011;Bircher et al, 2012;Rautiainen et al, 2012;Magagi et al, 2013) are also sparse in these areas, since measurements in mountainous terrains are costly to implement and were so far not in the focus of climatic studies. Although, the influence of soil moisture on the thermal regime of frozen ground was confirmed in many modeling studies (e.g., Hinkel et al, 2001;Boike et al, 2008;Westermann et al, 2009;Scherler et al, 2010) soil moisture measurements remain restricted to uncoordinated and project based installations (e.g., Hilbich et al, 2011;Rist and Phillips, 2005). Globally, there is a large data gap in terms of spatial and temporal soil moisture data at high elevation that needs to be filled.…”

“…It influences the physical properties of the subsurface (e.g., ice content, thermal conductivity, heat capacity, hydraulic conductivity, electrical conductivity, and permittivity), the energy and water exchange processes with the atmosphere (e.g., changing albedo, evaporation, infiltration rates, refreezing rates, latent heat release, ground heat flux, runoff, Hinkel et al, 2001;Boike et al, 2003Boike et al, , 2008Westermann et al, 2009Westermann et al, , 2011Scherler et al, 2010) and the characteristics of different permafrost landforms (e.g., differences of the above for soil, bedrock, rock glacier with coarse-or finegrained blocky material, talus slopes, steep, or flat terrain, Rist and Phillips, 2005).…”

“…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).…”