Firn

Firn is the porous snow layer that compacts into glacier ice. Firn density, temperature, and energy evolution shape surface elevation change and set the radar wave speed, which feeds directly into satellite altimetry and radar-estimates of englacial structure. Our group has built firn models in a finite-element framework so compaction, heat transport, and meltwater processes can be solved consistently and used with inverse methods to assimilate observations of compaction to initialize poorly constrained densification parameters. These constraints improve the interpretation of radar travel times, satellite altimetry trends, and can be used to reconstruct past climate from firn observations.