Characterizing permafrost soil active layer dynamics and sensitivity to landscape spatial heterogeneity in Alaska

Journal Article · Tue May 30 00:00:00 EDT 2017 · The Cryosphere Discussions

DOI:https://doi.org/10.5194/tc-2017-87· OSTI ID:1402081

Yi, Yonghong ^[1]; Kimball, John S. ^[1]; Chen, Richard ^[2]; Moghaddam, Mahta ^[2]; Reichle, Rolf H. ^[3]; Mishra, Umakant ^[4]; Zona, Donatella ^[5]; Oechel, Walter C. ^[5]

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1. The Univ. of Montana, Missoula, MT (United States)
2. Univ. of Southern California, Los Angeles, CA (United States)
3. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
4. Argonne National Lab. (ANL), Argonne, IL (United States)
5. San Diego State Univ., San Diego, CA (United States)

An important feature of the Arctic is large spatial heterogeneity in active layer conditions, which is generally poorly represented by global models. In this study, we developed a spatially integrated modelling and analysis framework combining field observations, local scale (~ 50 m) active layer thickness (ALT) and soil moisture maps derived from airborne low frequency (L + P-band) radar measurements, and global satellite environmental observations to investigate the ALT sensitivity to recent climate trends and landscape heterogeneity in Alaska. Model simulated ALT results show good correspondence with in-situ measurements in higher permafrost probability (PP ≥ 70 %) areas (n = 33, R = 0.60, mean bias = 1.58 cm, RMSE = 20.32 cm). The model results also reveal widespread ALT deepening since 2001, with smaller ALT increases in northern Alaska (mean trend = 0.32 ± 1.18 cm yr^-1) and much larger increases (> 3 cm yr^-1) across interior and southern Alaska. The positive ALT trend coincides with regional warming and a longer snow-free season (R = 0.60 ± 0.32). Uncertainty in the spatial and vertical distribution of soil organic carbon (SOC) was found to be the most important factor affecting model ALT accuracy. Here, potential improvements in characterizing SOC heterogeneity, including better spatial sampling of soil conditions and advances in remote sensing of SOC and soil moisture, will enable more accurate predictions of permafrost active layer conditions.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); USDOE
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1402081
• Journal Information: The Cryosphere Discussions, Vol. 2017; ISSN 1994-0440
• Publisher: European Geosciences Union
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES
Active layer
Permafrost