Circumpolar Deep Water and the West Antarctic Ice Sheet

* 9725024雅各布斯 该项目将研究侵入南极西海岸大陆架的绕极深水的动态，以及这种侵入对寒冷、稠密的底层水的产生以及对浮动冰川和冰舌底部融化的影响。 它将集中在阿蒙森海大陆架，特别是在松岛冰川、思韦茨冰川和盖兹冰架地区。 绕极深水（CDW）是一种相对温暖的水团（温度高于+1.0摄氏度），通常被海洋锋限制在大陆架的外缘，将此水团与较冷和较咸的大陆架沃茨分开。 然而，在阿蒙森海，大陆架的较深部分充满了几乎未稀释的CDW，这些CDW向上混合，将大量的热量输送到浮动冰川舌和冰架的底部。 松岛冰川下的融化速度平均每年十米的冰，当地的年融化速度达到二十米。 相比之下，罗斯冰架下的融化速度通常是每年20到40厘米的冰。 此外，松岛和思韦茨冰川都是非常快速的移动，并对西南极洲的区域冰量平衡有重大影响。 因此，该项目与南极冰川学有着重要的联系，特别是在评估全球变化对南极环境的综合影响方面。 该项目的具体目标是：（1）充分描绘大陆架锋面结构，以定量确定CDW流入、融水流出的主要路线，以及CDW影响的向西演变;（2）利用所获得的数据集来验证目前正在构建的冰下海洋环流的三维模型，（3）修正了原位融化对南极冰盖质量平衡的影响。 观测计划将在研究船Nathaniel B上进行。1999年2月和3月，帕尔默。 ***

*** 9725024 Jacobs This project will study the dynamics of Circumpolar Deep Water intruding on the continental shelf of the West Antarctic coast, and the effect of this intrusion on the production of cold, dense bottom water, and melting at the base of floating glaciers and ice tongues. It will concentrate on the Amundsen Sea shelf, specifically in the region of the Pine Island Glacier, the Thwaites Glacier, and the Getz Ice Shelf. Circumpolar Deep Water (CDW) is a relatively warm water mass (warmer than +1.0 deg Celsius) which is normally confined to the outer edge of the continental shelf by an oceanic front separating this water mass from colder and saltier shelf waters. In the Amundsen Sea however, the deeper parts of the continental shelf are filled with nearly undiluted CDW, which is mixed upward, delivering significant amounts of heat to the base of the floating glacier tongues and the ice shelf. The melt rate beneath the Pine Island Glacier averages ten meters of ice per year with local annual rates reaching twenty meters. By comparison, melt rates beneath the Ross Ice Shelf are typically twenty to forty centimeters of ice per year. In addition, both the Pine Island and the Thwaites Glacier are extremely fast-moving, and have a significant effect on the regional ice mass balance of West Antarctica. This project therefore has an important connection to antarctic glaciology, particularly in assessing the combined effect of global change on the antarctic environment. The particular objectives of the project are (1) to delineate the frontal structure on the continental shelf sufficiently to define quantitatively the major routes of CDW inflow, meltwater outflow, and the westward evolution of CDW influence; (2) to use the obtained data set to validate a three-dimensional model of sub-ice ocean circulation that is currently under construction, and (3) to refine the estiamtes of in situ melting on the mass balance of the antarctic ice sheet. The observational program will be carried out from the research vessel Nathaniel B. Palmer in February and March, 1999. ***