UNIVERSITY PARK, Pa. — Two incoming graduate students in the Department of Geography were awarded National Science Foundation (NSF) Graduate Research Fellowships (GRFPs) for 2021. Both want to improve climate change modeling; one in the Arctic, the other in the Antarctic.

Nicolle Di Domenico, who is pursuing a master of science, and Emma Robertson, who is pursuing a doctor of philosophy, said that undergraduate fieldwork experiences sparked their interest pursuing climate science.

Di Domenico’s area of interest is microtopography, or land area measured in square meters, in an Arctic landscape feature called polygonal ground. Polygonal ground is caused by the uneven thawing and refreezing of Arctic soils, which stores most of the world’s underground carbon and is warming two times faster than anywhere else on Earth.

“Mapping and monitoring polygonal ground is essential to understanding carbon release from soil to atmosphere,” Di Domenico said, “but until now, most models could not account for the carbon and methane release controlled by polygonal ground because the scale is too small.”

Di Domenico’s study will use data from the WorldView-3 satellite and machine learning to map the polygonal ground.

“If we can include polygonal ground-controlled carbon release in models, we will increase their accuracy, and better predict future climate change,” Di Domenico said.

Di Domenico’s adviser is Shujie Wang, an assistant professor of geography who specializes in remote sensing, modeling and the cryosphere, or places on Earth where the water is frozen.

“Nicolle’s research is novel and important,” Wang said. “Mapping the polygonal ground in the Arctic is a crucial step for us to examine the carbon emission from the permafrost landscapes. She is also building new methods to study this process, which will improve our understanding and capability in modeling the biochemical and biophysical processes in Arctic.”  

Di Domenico is currently in the process of reviewing her initial machine learning algorithms to determine which is best at identifying polygonal ground. She plans to give a presentation on her work in progress at the American Association of Geographers (AAG) in February 2022 in New York City. 

Robertson’s area of interest is modeling loss of mass on the Antarctic Ice Sheet (AIS). Studies have shown that the AIS has lost an average of 150 billion tons of mass every year since 2003, contributing about a millimeter to sea level rise every two years. Understanding how this will change in the future requires understanding how the air and oceans will warm and melt ice, but also how this warming will influence snowfall across the vast ice sheet.

“Atmospheric forcing, or how powerful storms affect surface melt, is poorly modeled, partly because of sparse observations in Antarctica,” Robertson said. “I will utilize ice core records, moisture source modelling, and outputs from climate models and atmospheric re-analyses to quantify the impact of atmospheric rivers on Antarctic ice sheet surface mass balance.”

One important aspect of her research is trying to determine whether there is a relationship between atmospheric rivers and the isotopic composition of different ice cores collected in West Antarctica, she said. 

Atmospheric rivers are relatively long, narrow bands of moisture in the atmosphere — like rivers in the sky — that transport most of the water vapor outside of the tropics. When the atmospheric rivers make landfall, they often release the water vapor as rain or snow, according to the National Oceanic and Atmospheric Administration.  

“The ice cores I’m using for my research date back to as early as 1785,” Robertson said. “Right now, I’m examining them over the years 1979 to 2010 to correspond with available data climate reanalyses. If I’m able to determine a relationship between atmospheric rivers and the isotopic composition of precipitation that becomes incorporated into the ice core record, I may be able to determine how these events have influenced Antarctic mass balance over longer timescales.”  

Robertson’s adviser is Luke Trusel, an assistant professor of geography who also focuses on the cryosphere.

“An ultimate goal of Emma’s research is to understand how atmospheric rivers have evolved in recent decades and centuries in response to natural climate variability and human-induced warming,” Trusel said. “This information would allow us to better understand how snowfall may change in the future in Antarctica and help constrain the ice sheet’s contributions to rising sea level.”