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

第一部分：南极底层水(AABW)是地球上最冷、最咸、密度最高的水，这是因为它在南极冰层的高纬度形成的方式。全球环流通常是通过在二维纬度/深度坐标空间中的输送来量化的(fi)。然而，AABW的形成、向北的flow以及大西洋、印度和太平洋fic盆地之间的分布基本上是三维过程。AABW在南极海岸周围几个不同的地点形成，特别是南部韦德尔海、西部罗斯海、阿德埃利海岸和普里兹湾。AABW是全球海洋翻转环流的关键组成部分之一，在几十年至千年的时间尺度上，在调节地球气候方面发挥着关键作用。第二部分：AABW向北部盆地输送的地图没有受到很好的限制，以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”，允许每一种AABW直接向北运输。在另一种极端情况下，有人建议ACC在所有陆架AABW来源到达北部盆地之前，将它们“混合”在一起。为了缩小理解上的差距，这一合作项目利用了三个互补的分析工具：以过程为导向的跨行政协调委员会AABW出口建模、高分辨率全球海洋模式和受观测约束的全球环流估计。提出了对AABW途径的识别和机理理解。该项目还将促进三名博士后研究人员和两名职业生涯早期教师的职业生涯，并将继续保持PI与一名外国研究人员之间的合作关系。该奖项反映了NSF的法定使命，并通过使用基金会的学术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.