Warming and Freshening in the Abyssal Southeastern Indian Ocean
Warming and Freshening in the Abyssal Southeastern Indian Ocean
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DOI：
10.1175/2008jcli2384.1
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发表时间：
2008-10-01
影响因子：
4.9
通讯作者：
Bullister, John L.
中科院分区：
文献类型：
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作者：
Johnson, Gregory C.;Purkey, Sarah G.;Bullister, John L.
利用从南极洲向北延伸至赤道的水文断面的两个密切抽样的高质量地点的数据，量化了1994/95年至2007年期间东印度洋深海水域的变暖和淡化。这些变化仅限于伊丽莎白公主海槽和澳大利亚-南极盆地的深海水域，东南印度洋海脊以北几乎没有明显的深海变化。与以前的研究一样，在这两个南部盆地的海底潜在温盐关系中观察到了显著的降温和清新。此外，对压力面的分析表明，在伊丽莎白公主海槽，深海增温约0.05摄氏度，并使1978年实际盐度尺度(pss-78)变新约0.01；在深海澳大利亚-南极盆地，增温约0.1摄氏度，淡水约0.005。这些12年的差异在两个深盆地的水柱底部几到数百分贝的95%可信区间内从零开始具有统计学意义。变暖和淡化都会降低海水的密度，导致水柱垂直膨胀。这些盆地低于3000 dbar的变化表明，当地海平面分别上升了1厘米和4厘米。2007年占领的瞬时示踪数据定性地表明，南部两个盆地发生变化的深海水域具有在过去几十年中暴露在海面上的重要成分，而在没有发现变化的东南印度洋海脊以北，经历过这种通风的深海水域的成分大大减少。
Warming and freshening of abyssal waters in the eastern Indian Ocean between 1994/95 and 2007 are quantified using data from two closely sampled high-quality occupations of a hydrographic section extending from Antarctica northward to the equator. These changes are limited to abyssal waters in the Princess Elizabeth Trough and the Australian-Antarctic Basin, with little abyssal change evident north of the Southeast Indian Ridge. As in previous studies, significant cooling and freshening is observed in the bottom potential temperature-salinity relations in these two southern basins. In addition, analysis on pressure surfaces shows abyssal warming of about 0.05 degrees C and freshening of about 0.01 Practical Salinity Scale 1978 (PSS-78) in the Princess Elizabeth Trough, and warming of 0.1 degrees C with freshening of about 0.005 in the abyssal Australian-Antarctic Basin. These 12-yr differences are statistically significant from zero at 95% confidence intervals over the bottom few to several hundred decibars of the water column in both deep basins. Both warming and freshening reduce the density of seawater, contributing to the vertical expansion of the water column. The changes below 3000 dbar in these basins suggest local contributions approaching 1 and 4 cm of sea level rise, respectively. Transient tracer data from the 2007 occupation qualitatively suggest that the abyssal waters in the two southern basins exhibiting changes have significant components that have been exposed to the ocean surface within the last few decades, whereas north of the Southeast Indian Ridge, where changes are not found, the component of abyssal waters that have undergone such ventilation is much reduced.