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

Area of Science:

• Geosciences
• Environmental Science
• Remote Sensing

Background:

• Arctic permafrost exhibits significant spatial heterogeneity in active layer conditions, poorly represented by global models.
• This heterogeneity leads to uncertainties in predicting regional ecosystem responses and climate feedbacks.

Purpose of the Study:

• To investigate the sensitivity of active layer thickness (ALT) to climate trends and landscape heterogeneity in Alaska.
• To develop a spatially integrated modeling and analysis framework for Arctic permafrost research.

Main Methods:

• Combined field observations, airborne L+P-band radar measurements for local-scale ALT and soil moisture mapping (~50 m resolution).
• Integrated global satellite environmental observations with a modeling framework.
• Analyzed ALT sensitivity to climate trends and landscape factors.

Main Results:

• Modelled ALT showed good correspondence with in situ measurements in high permafrost probability areas (PP ≥ 70%).
• Widespread ALT deepening observed since 2001, with significantly larger increases in interior and southern Alaska (> 3 cm yr⁻¹).
• ALT deepening correlated with regional warming and longer snow-free seasons (R = 0.60 ± 0.32).
• Uncertainty in soil organic carbon (SOC) distribution was the primary factor affecting modeled ALT accuracy, followed by soil moisture.

Conclusions:

• Improved characterization of SOC heterogeneity is crucial for accurate ALT predictions.
• Advances in remote sensing of SOC and soil moisture can refine permafrost modeling frameworks.
• The developed framework aids in understanding and predicting active layer dynamics in response to climate change.