Collaborative Research: Feedbacks between Orographic Precipitation and Ice Dynamics

Aschwanden/1644277该奖项支持一个项目，研究南极半岛的雨影现象(技术上称为地形降水)及其与冰雪覆盖的山脉的相互作用。地形降水形成了地球上最大的气候和生态梯度。在山脉迎风一侧上升的空气膨胀并冷却，冷凝其携带的水蒸气，产生暴雨或降雪。当空气在背风侧翼下降时，空气变暖和干燥，只剩下很少或几乎没有降水。这种降雪模式是由风和地形的相互作用造成的，假设是为了控制冰盖本身的形状。研究人员假设，降水和地形之间的反馈控制着冰通量和温度，影响基本条件(冻结和潮湿)和运动，在长时间尺度上可以通过侵蚀影响基本地形。作者建议通过将地形降水模式与平行冰盖模式(PISM)相耦合，研究地形驱动的降水、冰动力学、热力学和南极半岛北部基底侵蚀和抬升之间的反馈。使用理想化和更真实的几何图形，它们将从二维流带模型开始，该模型将扩展到三维，以确定反馈的强度作为基岩几何形状和地形降水梯度强度的函数。在南极半岛现代和未来的快速变化以及自上一次冰川盛期以来的通货紧缩的背景下，南极半岛被视为理想的案例研究。这项工作的更广泛影响包括通过捕捉当前模式中没有包括的与地形降水有关的反馈来加强预报模式。这可能会对气候变化制度下地形降水的影响提供更现实的评估。该项目将支持一名早期职业科学家和一名职业中期女性科学家，并将支持一名博士生，并为一名本科生提供暑期研究经验，作为REU的补充。该项目不需要在南极进行实地工作。

Aschwanden/1644277This 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.