NSFGEO-NERC: Investigating the direct influence of meltwater on Antarctic Ice Sheet dynamics

表面融化在南极洲周边地区很普遍，预计还会显着增加。这可能会影响海平面上升，因为它会让地表融化的水到达冰盖床，并改变流入海洋的冰川流量。这一机制在南极洲几乎没有受到关注，部分原因是我们团队的成员最近才发表了关于今天发生这种情况的证据。随着南极洲变暖，这一机制可能会变得越来越重要，我们将迈出理解和预测这些变化的第一步。我们将检验三个假设：(1)卫星数据显示的冰速的短期变化是表面融水到达南极半岛出口冰川床的结果，(2)这在今天的南极普遍存在，以及(3)这导致平均年冰流量显著增加。我们提出了一个由英国南极调查局(BAS)支持的关于南极半岛出口冰川的有针对性的实地活动，以结合成熟的和更多的实验技术来验证假设1。BAS将为现场工作提供支持，因为我们的现场距离Rothera研究站很近。目前的成果将包括直接比较现场融化速度(来自能源收支气象站)和冰的动态变化(来自GPS和无人驾驶飞行器)和冰下水流(来自被动地震仪和穿冰雷达)。我们还将进行全大陆范围的遥感调查，使用合成孔径雷达和多光谱图像来全面绘制地面冰上融化的水(最类似的工作集中在漂浮的冰架上)和短期速度变化。来自实地考察和遥感调查的综合新数据集将被用来检验我们的三个假设。冰川学界对南极冰架表面融化和水文学的兴趣正在迅速增长。该项目将把这一学科引向一个新的但相关的方向，并在理解地面冰对不断增加的融化速度的反应所涉及的不同过程方面取得重要进展。作为最早关注大气/冰-动力耦合这一方面的项目之一，我们将对表面融化引起的冰流速度短期变化的驱动因素和影响产生早期的洞察。例如，得出结论，表明融化的水直接影响南极的冰动态，这将对我们理解南极洲对大气变暖的反应具有重大影响，就像近20年前格陵兰岛首次发现这种现象时一样。这项工作还将对其他领域产生影响，因为地表到海床的融水流动可能会对冰流变学、冰川下水文学、海底融化和崩解、海洋环流和海洋生物地球化学产生影响。

Surface melting is widespread around the periphery of Antarctica and predicted to increase significantly. This could impact sea-level rise by allowing surface-derived meltwater to reach the ice-sheet bed and modify glacier flow into the ocean. This mechanism has received little attention in Antarctica, partly because evidence for it happening today has only recently been published, by members of our team. This mechanism is likely to become increasingly important as Antarctica warms and we will take the first steps towards understanding and predicting these changes. We will test three hypotheses: (1) short-term changes in ice velocity indicated by satellite data result from surface meltwater reaching the bed of outlet glaciers in the Antarctic Peninsula, (2) this is widespread in Antarctica today, and (3) this results in a measurable increase in mean annual ice discharge.We propose a targeted field campaign supported by the British Antarctic Survey (BAS) on an Antarctic Peninsula outlet glacier, to test hypothesis 1 using a combination of well-established and more experimental techniques. BAS will support the fieldwork because of our field site's proximity to Rothera Research Station. Immediate outcomes will include a direct comparison of in situ melt rates (from energy-budget weather stations) and ice dynamic changes (from GPS and uncrewed aerial vehicles) and subglacial water flow (from passive seismometers and ice-penetrating radar). We will also conduct a continent-wide remote sensing survey, using synthetic aperture radar and multi-spectral imagery to comprehensively map meltwater on grounded ice (most similar efforts have focused on floating ice shelves) and short-term velocity variations. Comprehensive new datasets from the field and remote-sensing surveys will be used to test our three hypotheses.There is rapid growth in the glaciology community's interest in surface melting and hydrology on Antarctic ice shelves. This project will take the discipline in a new, but related direction and make important progress in understanding the different processes involved in the response of grounded ice to increasing melt rates. As one of the first projects to focus on this aspect of atmosphere/ice-dynamics coupling, we will produce early insights into both the drivers and implications of short-term changes in ice flow velocity caused by surface melting. For example, showing conclusively that meltwater directly impacts Antarctic ice dynamics would have significant implications for our understanding of the response of Antarctica to atmospheric warming, as it did in Greenland when the phenomenon was first detected there nearly 20 years ago. This work will also have implications for other fields, as surface-to-bed meltwater flow may have implications for ice rheology, subglacial hydrology, submarine melting and calving, ocean circulation, and ocean biogeochemistry.