Participating Faculty, UW Quaternary Research Center
Fax: 206-543-0489 (shared)
Research Groups: Glaciology
I study glaciological problems related to derivation and interpretation of paleoclimate records from polar ice cores.
Ice found at different depths in a core may have come from very different places on the ice sheet surface, depending on the history of flow on a dynamic and changing ice sheet. In order to unravel the paleoclimate signals recorded in the ice, members of our extended research group measure surface velocities and strain rates on ice sheets using GPS methods. We also use ice-penetrating radar to detect internal layering (isochrones) within the ice. Those data, when combined with computer models of ice flow, can reveal the ice-flow patterns at depth. The age scale for the geochemical climate signals locked in the ice can then be calculated, and snowfall rates in the past can be inferred by comparing observed thicknesses of annual layers with model calculations of the thinning they have undergone due to ice flow.
We currently study the potential for developing overturned folds due to transient flow, and are also investigating the role of anisotropic crystal fabric in initiating flow disturbances.
My current research focuses on firn, the intermediate stage between new snow and solid ice. Firn comprises roughly the uppermost 100 meters of the polar ice sheets. The amount of air in the firn layer can change as climate changes, complicating efforts to estimate mass loss from the ice sheets by detecting changing heights of the surface from satellites. The age of the firn when it finally seals off air bubbles must be known in order to relate the timing of climate signals recorded in the solid ice, and climate signals carried in the trapped air, and this age difference can also change when climate changes.