AOSC Seminar by Dr. Brooke Medley, 4/08/2021
Dr. Brooke Medley
NASA Goddard Space Flight Center
Title: The importance of snow accumulation and firn evolution on assessing the Antarctic contribution to sea-level rise
One of the most robust methods for measuring ice-sheet mass balance uses satellite altimetry to measure changes in surface height through time and ultimately provide ice-sheet-wide volume change estimates. Interpretation of volume changes, however, requires ancillary information because there are several processes that generate height changes observable by satellite altimeters. The measured surface height change is a combination of signals, which reflect processes that involve ice or solid earth mass change, or even no mass change at all. Even if we remove the solid-earth processes, partitioning the remaining ice-sheet-volume change to the appropriate material densities remains a challenge. Specifically, volume change due to ice dynamics represents a change at the density of ice (917 kg m-3) whereas surface processes (snowfall, sublimation, melt) typically (but not always) represent change under much lower densities (200 kg m-3 – 600 kg m-3). Additionally, the role of surface processes on observed volume change varies substantially in space and time yet remains largely unmeasured. Here, we present techniques that use modelling to constrain snow accumulation and firn processes over the Antarctic Ice Sheet for improved mass balance studies. We further explore the relative importance of these fluctuations in determination of ice-sheet-wide mass balance and sea-level contribution and determine which processes are generating the largest uncertainties in our estimates.
Brooke Medley received a B.A. from Middlebury College in Vermont in 2005 and an M.S. in Physical Geography from Oregon State University in 2008. After two successful field seasons in West Antarctica in 2009 and 2010, she completed her Ph.D. at the University of Washington under her advisor Dr. Ian Joughin in 2013. After completing her Ph.D., she received a NASA postdoctoral research fellowship at NASA Goddard Space Flight Center, where she investigated snow accumulation over the Antarctic Ice Sheet. In 2015, she joined the Cryospheric Sciences Laboratory as a Physical Research Scientist at Goddard to investigate variations in firn thickness in relation to observed surface elevation changes in support NASA’s next generation laser altimetry mission: ICESat-2. She was the Deputy Project Scientist for NASA’s Operation IceBridge, a decade-long airborne survey of Earth’s polar regions, from 2018 through 2021 when the mission ended.
Contact: Jacob Wenegrat
Pre-seminar refreshment: N/A
Seminar: 3:30-4:30pm, Zoom
Meet-the-Speaker: 4:30-5:00pm, Zoom [For AOSC Students only]