Abstract
Ice streams are bounded by abrupt transitions in speed called shear margins. Some shear margins are fixed by subglacial topography, but others are thought to be self-organizing, evolving by thermal feedback to ice viscosity and basal drag which govern the stress balance of ice sheets. Resistive stresses (and properties governing shear-margin formation) manifest nonuniquely at the surface, motivating the use of subsurface observations to constrain ice sheet models. In this study, we use ice-penetrating radar data to evaluate three 3-D thermomechanical models of the Northeast Greenland Ice Stream, focusing on model reproductions of ice temperature (a primary control on viscosity) and subsurface velocity. Data/model agreement indicates elevated temperatures in the Northeast Greenland Ice Stream margins, with depth-averaged temperatures between 2 °C and 6 °C warmer in the southeast margin compared to ice in streaming flow, driven by vertical heat transport rather than shear heating. This work highlights complexity in ice divergence across stagnant/streaming transitions.
| Original language | English |
|---|---|
| Journal | Geophysical Research Letters |
| Volume | 46 |
| Issue number | 14 |
| Pages (from-to) | 8184-8193 |
| Number of pages | 10 |
| ISSN | 0094-8276 |
| DOIs | |
| Publication status | Published - 1 Jan 2019 |
Keywords
- Greenland
- ice sheet modeling
- model validation
- Northeast Greenland Ice Stream
- radar
- shear margin