Modeling the spatio-temporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape

Jitendra Kumar, Nathan Collier, Gautam Bisht, Richard T. Mills, Peter E. Thornton, Colleen M. Iversen, Vladimir Romanovsky
2016 The Cryosphere Discussions  
Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to atmosphere under warming climate. Ice-wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. The microtopography plays a critical role in regulating the fine scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for
more » ... derstanding the landscape behavior under current as well as changing climate. We present here an end-to-end effort for high resolution numerical modeling of thermal hydrology at real-world field sites, utilizing the best available data to characterize and parameterize the models. We develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites at Barrow, Alaska spanning across low to transitional to high-centered polygon, representing a broad polygonal tundra landscape. A multi-phase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using high resolution LiDAR DEM, microtopographic features of the landscape were characterized and represented in the high resolution model mesh. Best available soil data from field observations and literature was utilized to represent the complex heterogeneous subsurface in the numerical model. Simulation results demonstrate the ability of the developed modeling approach to model the complex thermal regimes across the sites. Our study provides insights into the critical role of polygonal tundra microtopography in regulating the thermal dynamics of the carbon rich permafrost soils. Study also highlights the importance of field-based observations of soil thermal and hydraulic properties for modeling-based studies of permafrost thermal dynamics and provides motivation for future observations by identifying gaps in our current understanding of the system.
doi:10.5194/tc-2016-29 fatcat:65deoq73gnegbgmikoedx5kxv4