Statistical Analyses of Permafrost Subsidence Based on High-resolution InSAR Data

Modeling climate-driven changes in permafrost, particularly surface subsidence caused by melting ground ice, remains a significant challenge for Earth System Models (ESMs) due to high spatial and temporal heterogeneity inherent in permafrost dynamics.

In this study, we investigate permafrost subsidence using the latest InSAR satellite data on ground displacement. With its meter-scale resolution, InSAR data provides a unique opportunity to examine the highly heterogeneous nature of permafrost subsidence unprecedented sampling density and coverage area. Statistical analyses were conducted on high-resolution data from PALSAR-2, covering five regions: Central North Slope, Inuvik region, Noatak River Basin, Yamal, and Yukon-Kuskokwim Delta.

Our findings reveal that permafrost subsidence exhibits consistent statistical properties. The Exponential Weibull distribution (EWD) emerged as the best-fit model across all regions and scales, effectively capturing the skewed and heavy-tailed nature of subsidence distributions. Correlation analyses between subsidence and potential driving factors, including climatic variables derived from ERA5-Land, soil class, and topography, showed low direct correlations. Additional analysis of clustered subsidence distributions in relation to local environmental conditions was performed to explore cross-regional commonalities.

Furthermore, we identified key requirements and limitations for improving permafrost subsidence analyses using InSAR data. First, the quality of observation data does not significantly improve beyond a certain threshold of sample size and resolution. While larger datasets produce smoother histograms, the overall shape of the distribution remains unchanged. Second, results from a series of Kolmogorov-Smirnov (K-S) tests show that subsidence data reliability is insensitive to any Gaussian distributed noises.

These insights highlight some robustness in the statistical nature of permafrost subsidence while emphasizing the need to focus on other factors, such as temporal and spatial coverage, to advance future analyses on permafrost subsidence under climate impacts. Additionally, the choice of data filters plays a critical role, as effective filtering can preserve large-scale patterns while mitigating atmospheric artifacts.

This study provides a statistical perspective on utilizing InSAR data to gain new insights into permafrost subsidence, while identifying current data limitations that urgently need to be addressed.