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、最密集的水，因为它是在高纬度的南极冰层中形成的。全球环流通常通过二维纬度/深度坐标空间中的输运来量化艾德。 然而，AABW的形成，向北的洋流以及大西洋，印度洋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少数几个不同的地点，特别是南部的威德尔海，西部的罗斯海，沿着阿德利海岸，并在普拉茨湾。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调节地球气候起着关键作用。第2部分：AABW运输到北方盆地的地图没有得到很好的限制，与以前的研究得出的结论相矛盾。在一个极端，ACC被认为是一个“管道”，只是允许每种AABW直接向北运输。在另一个极端，有人认为ACC在到达北方盆地之前将所有陆架AABW源“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种互补的分析工具：面向过程的AABW跨ACC出口建模、高分辨率全球海洋模型和观测约束下的全球环流估计。AABW通路的拟议识别和机制理解。该项目还将促进三名博士后研究人员和两名早期职业教师的职业发展，并将继续PI和外国研究人员之间的合作联系。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.