Spatial variability of permafrost active-layer thickness under contemporary and projected climate in Northern Alaska

Abstract

The active layer plays an important role in the functioning of environmental ecosystems and affects many human activities in the polar regions. Regional assessments and predictions of this parameter are critical for many physical and social applications. Large heterogeneity in near-surface permafrost characteristics, including the active layer, even over small distances, creates serious constraints to their evaluation across large geographic extents. Discrepancies between modeled climatic fields add to the uncertainties associated with predicting active-layer thickness (ALT) at regional scales. This study uses a stochastic approach, in combination with an equilibrium permafrost model, to map the geographic distribution of ALT and near-surface permafrost temperature on the North Slope of Alaska. GIS techniques are used to determine the spatial variabilityof ecosystem factors controlling the ground thermal regime within each grid cell of the permafrost model. To incorporate the uncertainty associated with the climate data, the model was forced byfour sets of gridded air temperature fields used widely in spatial modeling applications. A series of calculations created a spectrum of possible solutions for ALT and associated probabilityranges for each grid cell. Results are presented as a series of maps depicting geographic patterns of contemporaryand future ALT for the North Slope of Alaska.

Acknowledgements

We thank Cort Willmott (University of Delaware), Dmitry Drozdov (Russian Academy of Sciences), and Skip Walker (University of Alaska-Fairbanks) for reviewing an earlier version of this paper. This research was sponsored by the US National Science Foundation grant ARC-1002119 to the George Washington University, and NASA grants NNX09AI94G and 09-040 to the George Washington University, the University of Delaware and the University of New Hampshire. Opinions, findings, conclusions, and recommendations expressed in this paper are those of the authors, and do not necessarily reflect the views of NSF or NASA.