USAP-DC

Aschwanden/1644277

This award supports a project to study the phenomenon of the rain shadow (technically called orographic precipitation) in the Antarctic Peninsula and its interaction with a mountain range covered in ice and snow. Orographic precipitation gives rise to the largest climatic and ecological gradients on Earth. Air ascending on the windward side of the mountain range expands and cools, condensing the water vapor it carries and producing heavy rain- or snow-fall. As the air descends on the leeward flank, the air warms and dries out, leaving little-to-no precipitation. This pattern of snowfall, caused by the interaction of winds and the landscape, is hypothesized to control the shape of the ice cap itself. The investigators hypothesize that feedbacks between precipitation and topography control ice flux and temperature, impacting basal conditions (frozen versus wet) and motion, which over long time scales can affect basal topography via erosion.

The authors propose to investigate the feedbacks between orographically driven precipitation, ice dynamics, thermodynamics, and basal erosion and uplift over the northern Antarctic Peninsula by coupling an orographic precipitation model to the Parallel Ice Sheet Model (PISM). Using idealized and more realistic geometries, they will begin with a 2-D flow band model, which will be expanded into three dimensions to determine the strength of the feedbacks as a function of bedrock geometry and the intensity of the orographic precipitation gradient. The Antarctic Peninsula is targeted as the ideal case study, in the context of its rapid modern and future change as well as its deflation since the Last Glacial Maximum. The broader impacts of the work include the strengthening of predictive models by capturing feedbacks related to orographic precipitation not included in current models. This is likely to provide a more realistic assessment of the impacts of orographic precipitation in a regime of changing climate. The project will support an early career scientist and a female mid-career scientist and will support one PhD student, and provide summer research experience for one undergraduate student as an REU supplement. The project does not require field work in the Antarctic.

Person	Role
Aschwanden, Andy	Investigator and contact
Pettit, Erin	Co-Investigator

Antarctic Glaciology

Award # 1644277

USAP-1644277_1

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Parallel Ice Sheet Model (PISM) v2	None	exists
USAP-DC	Linear Theory of Orographic Precipitation QGIS Plugin	None	exists

1. Seroussi, H., Nowicki, S., Payne, A. J., Goelzer, H., Lipscomb, W. H., Abe Ouchi, A., Agosta, C., Albrecht, T., Asay-Davis, X., Barthel, A., Calov, R., Cullather, R., Dumas, C., Gladstone, R., Golledge, N., Gregory, J. M., Greve, R., Hatterman, T., Hoffman, M. J., … Zwinger, T. (2020). ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21<sup>st</sup> century. (doi:10.5194/tc-2019-324)