Quantifying soil thermal regimes and their controls across a discontinuous permafrost environment using a dense network of distributed temperature profiling systems
Abstract
In Arctic regions, the soil thermal regimes impact numerous hydrological and biogeochemical processes including soil permeability, water distribution, carbon and nitrogen cycling, and greenhouse gas emissions. While measuring soil and snow temperature time-series is essential to validate models that simulate heat, water, and carbon fluxes across the landscape, acquiring and processing data with sufficient spatial resolution to capture the heterogeneity of the system is still challenging. In this study, we investigate the plot to watershed scale heterogeneity in soil thermal regimes and their controls across a ~1.5 × 2 km watershed near Nome, Alaska. We applied a dense network of distributed temperature profiling (DTP) systems (~120 probes in total) to measure the vertically-resolved temperature of soil and snow. Each Probe recorded the temperature at a 15 min interval over more than a year, with sensors distributed vertically with 5 or 10 cm spacing along ~1 m depth. Snow thickness, soil frozen/thawed layer thickness, soil freeze/thaw durations, zero-curtain offset, thermal parameters, and other metrics were resolved from the time-series temperature data. The effects of vegetation, topography, and soil physio-chemical properties on the spatial variations of the derived parameters were investigated using laboratory analysis of soil cores and remote sensing products. The results of this study provide insights into the understanding of the thaw layer dynamics and the controls on soil thermal regimes. In particular, we found that the variability in the soil freeze-thaw timing and amplitude was strongly impacted by the snow cover dynamics and the soil water content that were both partly linked to topography and vegetation cover. The obtained information is expected to be useful for improving predictions of soil hydro-biogeochemical dynamics.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.B15A1412W