School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
Research Institute of Oceanography, College of Natural Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
Sci Rep. 2022 Jul 16;12(1):12175. doi: 10.1038/s41598-022-16331-y.
Antarctic Bottom Water (AABW) characteristics, derived from multiple water sources with various properties, are significantly affected by and contribute to climate change. However, the underlying causes of changes in AABW characteristics are not well-understood. In this study, we aimed to analyse the east-west contrasting pattern of AABW characteristics in the Southern Indian Ocean (SIO) over the last three decades. We show that AABW has become warmer and more saline in the western SIO (WSIO) but warmer and fresher in the eastern SIO (ESIO) in 2010s than in 1990s. The warming and salinification of WSIO AABW are primarily explained by changes in source water mixing ratios, although the source water properties also significantly contribute to the observed changes. In contrast, the warming and freshening of ESIO AABW cannot be explained without considering changes in the source water properties as the direction of AABW salinity change due to source water mixing ratios is opposite (salinification) to that of observations (freshening). The east-west contrasting pattern of AABW salinity changes and more rapid warming in the ESIO have important consequences for poleward AABW transport and sea-level rise within and beyond the SIO.
南极底层水（AABW）的特性来源于具有不同特性的多种水源，受气候变化的影响很大，并对其产生贡献。然而，AABW 特性变化的根本原因尚不清楚。在本研究中，我们旨在分析过去三十年南印度洋（SIO）东西部 AABW 特性的对比模式。结果表明，与 20 世纪 90 年代相比，2010 年代西印度洋（WSIO）的 AABW 变暖且更咸，而东印度洋（ESIO）的 AABW 变暖且更淡。WSIO AABW 的变暖与盐度增加主要归因于源水混合比例的变化，尽管源水特性也对观测到的变化有显著贡献。相比之下，如果不考虑源水特性的变化，ESIO AABW 的变暖与淡化就无法得到解释，因为源水混合比例导致的 AABW 盐度变化方向（盐化）与观测结果（淡化）相反。AABW 盐度变化的东西对比模式以及 ESIO 更快的变暖对 SIO 内外的 AABW 向极输送和海平面上升具有重要影响。
