Leveraging Field and Modelling Methods to Interrogate the Influence of Seasonally Frozen Ground on Snowmelt Partitioning

Almost a quarter of the Earth’s surface consists of seasonally frozen ground (SFG), which significantly overlaps with boreal wetland ecosystems. Although soil frost is known to influence watershed hydrology, it is difficult to understand the hydrological impacts of the coupled interaction between SFG, temperature, and snowpack. Snowpack insulates the soil layers in cold climates, making soil frost less likely to form, whereas low winter temperatures (leading to less snowpack) reduce this insulation effect and contributes to the formation of deeper soil frost. Elucidating this relationship is crucial, as both snow depth and soil frost depth play an important role in determining the volume of spring runoff in a region. This is because the timing of frost layer disappearance depends on the time it takes for snow to melt; it is only once the snowpack has melted that the soil frost layer begins to melt as well. In addition, wetland systems are hydrologically unique, as their upper soil layers retain high moisture levels which can lead to increased frost content in the soil, thereby influencing the flow of snowmelt leaving the watershed.  The amount of water available for evapotranspiration (ET) or groundwater recharge can therefore be impacted by the complex interactions between snowmelt, frost content, and infiltration and have cascading affects for the local ecosystem during the next growing season. In our research, we utilize existing field and climate datasets alongside integrated, land surface models to better understand the pathways through which frost and snowpack affect the  hydrological connectivity within forested wetland systems in Minnesota