Deep internal layers

Current projects:

 

Past projects:

Using IceBridge data to relate the response of interior ice to past and future changes in flow of ice streams and fast outlet glaciers, with PI Howard Conway and Ed Waddington, funded by NASA

Changes in activity of fast-flowing outlet glaciers and ice streams in Antarctica and in Greenland exert strong control on the mass balance of the ice sheets through discharge of inland ice to the ocean. Furthermore, recent rapid changes in discharge of these fast-flowing outlets suggest that dynamical responses to warming play a much larger role in the future mass balance of ice sheets than previously considered. Observations show strong coupling between coastal regions and inland ice, which opens the possibility that continued ice discharge from the interior of the ice sheets to the ocean could cause ongoing and possibly rapid rise in sea level. We use data and models to study the response of the interior of ice sheets to past changes at their margins. This is a necessary step toward understanding how ice sheets will respond to future possible forcing; understanding the past is also needed to give context to present-day behavior.

Accumulation rate, ice flow, and divide-position history of Central West Antarctica with Ed Waddington, Tom Neumann, Howard Conway, and TJ Fudge, funded by NSF

In my research I also employ inverse methods. Ice-flow models are powerful tools, but they require estimates of initial conditions and boundary conditions that are often largely unknown. In an inverse problem the data have resulted from a known process that depends on some unknown parameter values or boundary conditions that we want to find. In particular, radar-observed internal layers in glaciers and ice sheets are well-suited data for inverse problems. We use radar layers, accumulation-rate estimates, ice-surface velocities, and modern ice thickness to infer histories of accumulation rate, ice thickness, and ice-divide position. Using our ice-flow model we assess how the signal we want to recover is represented in realizations of the available data. Using the available data we solve a suite of inverse problesm to bracket the most likely history of the West Antarctic Ice Sheet (WAIS) Divide. Understanding the history of the ice divide is necessary to interpret ice-core records and to estimate future behavior of the WAIS.