Linking Inundation Patterns and Dynamics in a Permafrost Landscape to Hydrologic, Thermal, Biogeochemical and Ecosystem Processes

Abstract:

The Arctic coastal plain is characterized by multi-scale geomorphic features including thaw lakes, drained thaw lake basins, and clusters of ice wedge polygons composed of troughs, centers, and rims. The topographic and subsurface properties of these features control the lateral and vertical drainage pathways of snow melt and precipitation as well as the spatial and temporal dynamics of standing water in the landscape. The Next Generation Ecosystem Experiment, NGEE-Arctic, project combines multi-scale in-situ and remote surface and subsurface observations that quantify the interactions between landscape structure, hydrology, the carbon cycle and energy balance of Arctic permafrost environments, with the aim of improving representation of Arctic ecosystem processes in global climate models. Data and models from the project show distinct relationships exist between the hydro-geomorphic features mapped on the ground and observed in remote sensing imagery, and the measured in-situ thermal, biogeochemical and ecosystem responses coincident with those features. The relationships between micro-topographic setting, snow distribution, inundation, subsurface temperature and thaw depth observed at the NGEE Barrow field sites are now well reproduced in process resolving models such as Pflotran and the Arctic Terrestrial Simulator. Current modeling efforts are investigating how topographically controlled thermal-hydrologic dynamics impact the carbon cycle. The next challenge is to scale these relationships for application in a global climate model grid cell to enable pan-Arctic predictions of future change, including the change in topography and inundation resulting from thawing permafrost and melting ground ice. NGEE-Arctic is funded by the DOE Office of Science, Biological and Environmental Research program.