Spatially Resolved Projections of Carbon Releases from Thawing Polygonal Tundra

Abstract:

Arctic wetlands contain significant stores of organic carbon that are potentially vulnerable to release to the atmosphere as Arctic temperatures increase. Projecting the fate of that carbon is particularly difficult for polygonal tundra because of the strong control that organized microtopography plays in the hydrology and carbon cycle in those regions. A comprehensive microtopography-resolving modeling strategy for projecting the release of carbon from warming polygonal tundra has recently been developed. The strategy combines a novel multifaceted simulation capability, workflows for developing high-resolution computational meshes, and approaches for soil parameter estimation. Central to the approach is the Arctic Terrestrial Simulator, a highly parallel simulation tool that couples models of surface and subsurface thermal hydrology with phase change, surface energy balance, snow thermal processes, snow spatial distribution, and soil carbon dynamics all in an extensible and flexibly configured framework. We will present projections of future carbon release from thawing polygonal ground at the Barrow Environmental Observatory. These simulations, which are driven by climate projections in the RCP8.5 scenario, resolve hydrologic processes at the submeter scale to capture variations in soil moisture and soil carbon dynamics across polygon centers, rims, and troughs. We compare results for high- and low-centered polygons, focusing on the integrated effects of microtopography on hydrology and carbon release. This work was supported by LANL Laboratory Directed Research and Development Project LDRD201200068DR and by the The Next-Generation Ecosystem Experiments (NGEE Arctic) project. NGEE-Arctic is supported by the Office of Biological and Environmental Research in the DOE Office of Science.