The heat flow from the earth is an important boundary condition in ice sheet models because it influences the temperature at the base of an ice sheet. This then determines whether the ice sheet can flow fast by sliding over the bedrock or instead is frozen to the bedrock. Defining limits on the heat flow, termed geothermal flux, in Antarctica will improve our understanding of current ice sheet movement and future sea-level rise. Despite the importance of geothermal flux, it is very poorly constrained in Antarctica, largely because it is difficult to measure directly through the often kilometer-thick layer of ice covering the ground surface. The lack of both direct observations and knowledge of Antarctic geology means that remotely sensed interpretations of geothermal flux are poorly constrained and can vary widely.

In this paper, we present three new constraints of geothermal flux in the Ross Ice Sheet, Antarctica at Roosevelt Island, Engelhardt Ridge, and Shabtaie Ridge. The Roosevelt Island constraint includes a newly measured basal temperature. For Shabtaie and Engelhardt ridges, we used the fact that both domes have a stratigraphic feature called a “Raymond Arch”, which is visible in a radargram of the surface. A Raymond Arch only forms if the bed is frozen, and indicates that temperature at the bed must be at or below the melting point. Thus an inference of maximum basal temperature can be made.

These new inferences of geothermal flux (Roosevelt: 84 ± 13 mW/m2; Engelhardt: 85 ± 11 mW/m2; Shabtaie: 75 ± 10 mW/m2) indicate that previous inferences of high heat flow on the Ross Ice Sheet from remotely sensed data are not widespread. In fact, these values are comparable to flux values in the Basin and Range province in the Western United States, which is a well-known analog to the West Antarctic Rift System.

Surabhi Biyani

I started working on this project with T.J. Fudge through the NASA Space Grant Summer Undergraduate Research Program in 2018, which was the summer after my freshman year at UW. I started out not knowing much about numerical modeling or ice sheet dynamics, but learned how to use an ice-and-heat flow model to understand how climate forcings impact ice flow over time. I wrote a computer program to estimate the geothermal heat flux using surface temperature and precipitation histories as well as ice-flow parameterizations. My project became the basis of this paper published in Geophysical Research Letters in 2019. Experiencing the process of taking a research project from just an idea all the way to an AGU presentation and a published paper has given me invaluable technical and communication skills. It also gave me the confidence to continue my research career, which has included research on precipitation in GCMs this past summer and a NOAA Hollings Internship at GFDL where I will continue working with climate models this coming summer. The research opportunities available at University of Washington PCC-affiliated departments have prepared me well as I start thinking about graduate school and my plans for the future.

Surabhi Biyani is a 3rd year undergraduate at UW studying Earth and Space Sciences and Atmospheric Sciences. She also works at the PCC as an undergraduate assistant.