Minowa Masahiro, Sugiyama Shin, Ito Masato, Yamane Shiori, Aoki Shigeru
Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan.
Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan.
Nat Commun. 2021 Jul 9;12(1):4209. doi: 10.1038/s41467-021-23534-w.
Basal melting of ice shelves is considered to be the principal driver of recent ice mass loss in Antarctica. Nevertheless, in-situ oceanic data covering the extensive areas of a subshelf cavity are sparse. Here we show comprehensive structures of temperature, salinity and current measured in January 2018 through four boreholes drilled at a ~3-km-long ice shelf of Langhovde Glacier in East Antarctica. The measurements were performed in 302-12 m-thick ocean cavity beneath 234-412 m-thick ice shelf. The data indicate that Modified Warm Deep Water is transported into the grounding zone beneath a stratified buoyant plume. Water at the ice-ocean interface was warmer than the in-situ freezing point by 0.65-0.95°C, leading to a mean basal melt rate estimate of 1.42 m a. Our measurements indicate the existence of a density-driven water circulation in the cavity beneath the ice shelf of Langhovde Glacier, similar to that proposed for warm-ocean cavities of larger Antarctic ice shelves.
冰架的底部融化被认为是近期南极洲冰量损失的主要驱动因素。然而，覆盖次冰架空腔广大区域的现场海洋数据却很稀少。在此，我们展示了2018年1月通过在南极洲东部朗霍夫德冰川一个约3公里长的冰架上钻的四个钻孔所测量的温度、盐度和水流的综合结构。测量是在234 - 412米厚的冰架下方302 - 12米厚的海洋空腔中进行的。数据表明，经过改良的温暖深层水在分层的浮力羽流下方被输送到陆架冰区域。冰 - 海洋界面处的水温比原地冰点高0.65 - 0.95°C，由此得出的平均底部融化速率估计为1.42米/年。我们的测量表明，在朗霍夫德冰川冰架下方的空腔中存在由密度驱动的水体循环，这与为更大的南极冰架的温暖海洋空腔所提出的情况类似。
