Airborne-radar and ice-core observations of snow accumulation in West Antarctica
Airborne-radar and ice-core observations of snow accumulation in West Antarctica
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南极洲西部积雪的机载雷达和冰芯观测
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发表时间：
2014
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通讯作者：
B. Medley
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作者：
B. Medley
南极洲西部积雪的航空雷达和冰芯观测布鲁克混合泳监督委员会主席：伊恩R。Joughin应用物理实验室世界上的冰盖储存了足够的水，可以使全球海平面上升几十米，因此，其大小的任何波动都会导致海平面上升或下降。与海洋交换的净质量-定义为质量平衡-决定了冰川对海平面的贡献，并且是在内部积累的雪和在冰盖外围排入海洋的冰的差异。虽然远程获取表面速度的新技术改进了流量测量，但在大部分冰盖上，积雪仍然无法测量。这项工作旨在提高我们对南极洲两个变化最快的冰川（Pine Islan d和Thwaites）的雪积累的理解。具体来说，我们使用两个机载雷达系统来成像和跟踪近地表内部地层测量两个冰川的积雪速率。这种方法允许调查的空间和时间的变化积累在catchmen的t尺度，这是必不可少的确定冰川物质平衡。对松岛和思韦茨冰川上雷达导出的积累率s的检查揭示了几个结果，包括：（1）1980年至2009年间累积量没有表现出明显的趋势，（2）松岛和思韦茨的海平面贡献增加了两倍，从20世纪90年代中期的+0.09毫米/年增加到+0.27毫米/年到2010年，（3）在冰芯和雷达记录中都观察到，在1944-1984年和1985- 2009年之间发生了向更高积累的转变，（4）大气模式足以取代在观测较少的地区的积累测量。这些发现表明，积累并没有同时补偿该地区增加的冰排放，因此，这些冰川对海平面的贡献正在增加。此外，最近向更高的平均积累的转变表明，这些冰川可能比最初认为的更早失去平衡。
Airborne-radar and ice-core observations of snow ac cumulation in West Antarctica Brooke Medley Chair of the Supervisory Committee: Dr. Ian R. Joughin Applied Physics Laboratory The world’s ice sheets store enough water to raise global eustatic sea level by several tens of meters, and therefore, any fluctuations in their size will cause sea level to rise or fall. The ne t mass exchanged with the ocean – defined as the mass balance – determines the glacial contribution to sea level and is the difference in snow accumulated in the interior and ice discharged into the ocean at the ice sheet peripher y. While new techniques in remotely acquired surface velocities lead to improved discharge measu r ments, snow accumulation remains unmeasured over much of the of the ice sheet. This work aims to improve our understanding of sno w accumulation over two of the most rapidly evolving glaciers in Antarctica: Pine Islan d and Thwaites. Specifically, we use two airborne radar systems to image and track the nearsurface internal stratigraphy to measure snow accumulation rates over both glaciers. This method allows for investigation of the spatial and temporal variations in accumulation at the catchmen t-scale, which is essential for determining glacier mass balance. Examination of the radar-derived accumulation rate s over Pine Island and Thwaites glaciers revealed several results including: (1) ac cumulation exhibited no significant trend between 1980 and 2009, (2) the sea-level contributi on from Pine Island and Thwaites tripled from +0.09 mm yr -1 in the mid-1990s to +0.27 mm yr -1 by 2010, (3) a shift towards higher accumulation occurred between 1944–1984 and 1985–20 09, observed in both ice core and radar records, and (4) atmospheric models are an adequate replacement for accumulation measurements in areas with few observations. These findings indicate that accumulation is not c oncurrently compensating the enhanced ice discharge from the region, and as a result, the sea-level contribution from these glaciers is increasing. Furthermore, a recent shift towards hi gher mean accumulation suggests these glaciers might have been out of balance earlier tha n originally thought.