School of Environment, University of Auckland, Auckland, New Zealand.
NIWA, Wellington, New Zealand.
Sci Rep. 2023 Mar 8;13(1):3873. doi: 10.1038/s41598-023-31008-w.
Antarctic Bottom Water (AABW) stores heat and gases over decades to centuries after contact with the atmosphere during formation on the Antarctic shelf and subsequent flow into the global deep ocean. Dense water from the western Ross Sea, a primary source of AABW, shows changes in water properties and volume over the last few decades. Here we show, using multiple years of moored observations, that the density and speed of the outflow are consistent with a release from the Drygalski Trough controlled by the density in Terra Nova Bay (the "accelerator") and the tidal mixing (the "brake"). We suggest tides create two peaks in density and flow each year at the equinoxes and could cause changes of ~ 30% in the flow and density over the 18.6-year lunar nodal tide. Based on our dynamic model, we find tides can explain much of the decadal variability in the outflow with longer-term changes likely driven by the density in Terra Nova Bay.
南极底层水（AABW）在南极陆架上形成并随后流入全球深海后，与大气接触几十年到几个世纪后储存热量和气体。来自西部罗斯海的高密度水是 AABW 的主要来源，过去几十年其水特性和体积发生了变化。在这里，我们使用多年的系泊观测结果表明，流出的密度和速度与由 Terra Nova 湾密度控制的 Drygalski 海峡释放一致（“加速器”）和潮汐混合（“刹车”）。我们认为潮汐每年在春分和秋分在密度和流中产生两个峰值，并且可能导致在 18.6 年的月球节点潮汐中流和密度变化约 30%。基于我们的动力模型，我们发现潮汐可以解释流出的大部分十年际变化，而长期变化可能是由 Terra Nova 湾的密度驱动的。
