Research

Remote sensing of ground ice

Where permafrost is rich in ground ice, warming and disturbances can induce terrain subsidence, slumping, and collapse. However, we lack spatially resolved information on the controls on and susceptibility instability. In particular, we lack fine-scale maps of ground ice over most of the Arctic. I am currently exploring the subseasonal dynamics of thaw subsidence to constrain ice contents at the top of the permafrost.

Acceleration of seasonal subsidence measured by Sentinel-1 in an extreme summer such as 2019 is an indicator of ice-rich permafrost.

Permafrost terrain dynamics

Thaw slumps are among the most dynamic landforms that result from permafrost degradation. I am particularly interested in small slumps that feature a permanent or intermittent debris veneer on top of the ice-rich materials. Debris exerts a fundamental control on thaw slump trajectories. The coarse-grained nature of the debris predisposes the slump shown on the left to episodic retreat during exceptionally warm periods.

Complex feedback processes control the backwasting of such debris-covered thaw slumps.

Scattering models and estimation algorithms for Arctic environments

Arctic ecosystems present numerous challenges for remote sensing models and estimation algorithms, including microtopographic features such as ice wedge polygons and organic soils. I am developing bespoke remote sensing solutions for measuring permafrost terrain changes, soil moisture, and vegetation moisture. The theoretical and empirical characterization of model and estimation errors is an integral component of my work.

In the permafrost wetland with degrading ice-wedge polygons, our KMWG interferometric speckle model fits the observations better than existing models (green and yellow).