Augmentation of the USArray sites with temperature profilers

Abstract
The ground temperature variability across the Arctic landscape depends on the air temperature, snow cover, moisture content, vegetation, terrain, soil properties and related environmental variables. A juxtaposition of all these factors results in a highly heterogeneous distribution of the ground temperature, active layer thickness and permafrost conditions. As a result, prediction of subsurface temperature dynamics remains challenging and mean temperatures for a study region may not account for "hot spots" of change, which alone could significantly contribute to thaw and associated carbon emissions. A solution is to sample (record) temperature regimes within different ecotypes and environment conditions, and build a portfolio of subsurface thermal regimes across various ground conditions. The proposed ground temperature profilers will supplement the existing data loggers and provide means to sample the ground temperature regime in currently underrepresented ecotypes to increase our knowledge of permafrost variability across Alaska and Northern Canada.

Background/Justification/Objectives:
Starting in 2015, NASA's Terrestrial Ecology Program has been conducting the Arctic-Boreal Vulnerability Experiment (ABoVE), which is focused on a large-scale study of environmental change, including warming and thawing of permafrost soils leading to decomposition of long-frozen organic matter. Thawing and freezing of ground material is affected by many factors, with air temperature, vegetation, thermal properties of the ground material, snow accumulation, and soil moisture among the most significant. The range of spatial and temporal variability in these variables determines the extent and properties of permafrost, which is highly variable across the ABoVE domain. Permafrost temperature and ground properties determine how vulnerable the permafrost is to thaw, thus the rate at which degradation is occurring and will occur in future, as well as the carbon biogeochemistry and hydrology changes that will ensue. This is a central part of ABoVE’s overarching science question, which is “How vulnerable or resilient are ecosystems and society to environmental change in the arctic and boreal region of western North America?” It also addresses the first of ABoVE’s science objectives, which is “Determine how interactions among vegetation, hydrology & disturbances mediate permafrost vulnerability and resilience to climate change.