Collaborative Research: Geophysical Study of Ice Stream Stick-slip Dynamics

Winberry/0944794该奖项支持一项为期三年的研究，研究西南极惠兰冰流(Wis)的持续减速和粘滑运动。了解冰流的动态行为对于预测西南极冰盖(WAIS)的未来至关重要。尽管是南极洲研究得最好的冰流之一，但威斯康星令人惊讶的流动特征仍然需要跨学科的研究。最近的估计表明，威斯康星州可能在50年内停滞不前，导致西南极西伯利亚海岸部分的物质平衡发生重大变化。持续停滞的原因并不为人所知，可能(因果或巧合)与粘滑行为有关。我们最近对WIS粘滑运动的研究表明，所有滑移事件都是从冰流上的一个共同位置成核的，这表明相对较小的(直径约10公里)区域对这一大冰流(长100公里，宽100公里)的流动施加了基本控制。我们假设这是一个床层强度增加的区域，我们的测量将解决这一假设。我们将在冰流上部署一系列GPS接收器和地震仪，精确定位成核区，以便进行全面的地面地球物理调查，确定成核点处的床层物理性质。地面地球物理计划将包括反射、地震和冰层穿透雷达研究，这些研究将更好地约束假设的高摩擦成核带及其周围地区的性质。滑动事件还会产生地震能量，这些能量可以记录到距离冰流100公里的地方，因此，GPS和地震仪的部署也将有助于我们将地震波形与滑动事件期间发生的快速运动直接联系起来。将破裂过程与地震辐射联系起来的能力增强，将使我们能够使用存档的地震记录来探索20世纪后半叶WIS行为的变化。这项研究的更广泛影响包括改进了对冰盖动力学的了解，这仍然是气候系统中一个受约束程度较低的组成部分，因此限制了我们预测地球对气候变化反应的能力。这项科学工作包括两名研究生的教育和一名博士后学者的继续培训，从而有助于培养下一代极地科学家。我们将通过与媒体的互动让更广泛的公众接触极地科学，并利用项目将K-12教育工作者纳入我们的实地工作。

Winberry/0944794This award supports a three-year study of the ongoing deceleration and stick-slip motion of Whillans Ice Stream (WIS), West Antarctica. Understanding the dynamic behavior of ice streams is essential for predicting the future of the West Antarctic Ice Sheet (WAIS). Despite being one of the best-studied ice streams in Antarctica, the surprising flow characteristics of WIS continue to demand interdisciplinary research. Recent estimates indicate that the WIS may stagnate within 50 years, resulting in a significant change to the mass balance of the Siple Coast sector of West Antarctica. The reasons for the ongoing stagnation are not well known, and are possibly linked (causally or coincidentally) to the stick-slip behavior. Our recent work on WIS stick-slip motion suggest that all slip events nucleate from a common location on the ice stream, suggesting that a relatively small (approximately 10 km in diameter) region of the exerts fundamental control over the flow of this large ice stream (100s of km long and 100 kilometers wide). We hypothesize that this is a region of increased bed strength and our measurements will address that hypothesis. We will deploy a series of GPS receivers and seismometers on the ice stream to accurately locate the nucleation region so that a comprehensive ground based geophysical survey can be conducted to determine the physical properties of bed at the nucleation point. The ground geophysical program will consist of reflection seismic and ice-penetrating radar studies that will better constrain the properties of both the hypothesized higher-friction nucleation zone and the surrounding regions. Slip events also generate seismic energy that can be recorded 100s of km away from the ice stream, thus, the GPS and seismometer deployment will also aid us in relating seismic waveforms directly with the rapid motion that occurs during slip events. The increased ability to relate rupture processes with seismic emissions will allow us to use archived seismic records to explore changes in the behavior of WIS during the later half of the 20th century. Broader impacts of this study include improved knowledge ice sheet dynamics, which remain a poorly constrained component of the climate system, thus, limiting our ability to predict the Earth's response to climate change. The scientific work includes the education of two graduate students and continued training of one post-doctoral scholar, thus helping to train the next generation of polar scientists. We will expose the broader public to polar science through interactions with the media and by take advantaging of programs to include K-12 educators in our field work.