Collaborative Research: The Antarctic Circumpolar Current: A Conduit or Blender of Antarctic Bottom Waters?

第 1 部分：由于南极冰层高纬度地区的形成方式，南极底层水 (AABW) 是地球上最冷、最咸、密度最大的水。全球循环通常通过二维纬度/深度坐标空间中的传输来量化。 然而，AABW 的形成、向北流动以及大西洋、印度和太平洋盆地之间的分布基本上是三维过程。 AABW 形成于南极海岸周围的几个不同地点，特别是威德尔海南部、罗斯海西部、阿德利海岸沿线和普里兹湾。 AABW是全球海洋翻转环流的关键组成部分之一，在几十年到千年的时间尺度上对地球气候的调节发挥着关键作用。第 2 部分：AABW 向北部盆地输送的绘图没有得到很好的约束，之前的研究得出了相互矛盾的结论。在一种极端情况下，ACC 被认为是一条“管道”，仅允许每种 AABW 直接向北传送。在另一个极端，有人建议 ACC 在所有陆架 AABW 源到达北部盆地之前将其“混合”在一起。为了缩小理解上的差距，这个合作项目利用了三种互补的分析工具：跨 ACC 的 AABW 输出的面向过程的模型、高分辨率的全球海洋模型以及全球环流的观测受限估计。拟议的 AABW 途径的识别和机制理解。该项目还将促进三名博士后研究人员和两名早期职业教员的职业发展，并将继续 PI 和一名外国研究员之间的合作联系。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Part 1: Because of the manner in which it is formed at high latitudes in the Antarctic ice, Antarctic Bottom Water (AABW) is the coldest, saltiest and densest water on the planet. The global circulation of is often quantified via the transport in a two-dimensional, latitude/depth coordinate space. However, AABW formation, northward flow and distribution between the Atlantic, Indian and Pacific basins are fundamentally three-dimensional processes. AABW is formed in a handful of distinct sites around the Antarctic coast, notably the southern Weddell Sea, the western Ross Sea, along the Ad´elie coast, and in Prydz Bay. AABW is one of the key components of the global ocean overturning circulation, and plays a critical role in regulating Earth's climate, on multi-decadal-to-millennial time scales. Part 2: Mapping of AABW transport to northern basins is not well constrained, with conflicting conclusions drawn in previous studies. At one extreme the ACC has been suggested to be a “conduit" that simply allows each variety of AABW to transit directly northward. At the other extreme, it has been suggested that the ACC “blends" all shelf AABW sources together before they reach the northern basins. To close the gap in understanding, this collaborative project draws on three complementary analytical tools: process-oriented modeling of AABW export across the ACC, a high-resolution global ocean model, and an observationally-constrained estimate of the global circulation. The proposed identification and mechanistic understanding of AABW pathways. This project will also advance the careers of three postdoctoral researchers and two early-career faculty members, and will continue collaborative links between the PI and a foreign investigator.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.