Extrapolating active layer thickness measurements across Arctic polygonal terrain using LiDAR and NDVI data sets

Area of Science:

• Geosciences
• Remote Sensing
• Arctic Studies

Background:

• Active layer thickness (ALT) is crucial for Arctic terrestrial models but difficult to measure at large scales using in situ methods.
• Microtopography significantly influences ALT, necessitating high-resolution spatial data for accurate modeling.

Purpose of the Study:

• To develop and validate a remote sensing approach for estimating centimeter-scale ALT in Arctic ice-wedge polygon terrain.
• To provide spatially explicit ALT data for improving Arctic terrestrial models and understanding permafrost dynamics.

Main Methods:

• Utilized a machine learning data-fusion algorithm combining LiDAR and WorldView-2 multisensor data.
• Derived topographic and spectral metrics to estimate ALT at a 2 m spatial resolution over a 5 km² area in Barrow, Alaska.

Main Results:

• Achieved high accuracy in ALT estimation (r² = 0.76, RMSE ±4.4 cm) when compared to ground-based measurements.
• Demonstrated that while regional ALT averages are influenced by climate, local eco-hydro-geomorphic factors control smaller-scale variability.

Conclusions:

• The developed remote sensing approach offers a viable method for mapping ALT at high spatial resolution across large Arctic regions.
• Accurate ALT mapping is essential for better understanding and predicting the coupled dynamics of permafrost, hydrology, and land-surface processes.