Freshening drives contraction of Antarctic Bottom Water in the Australian Antarctic Basin
Freshening drives contraction of Antarctic Bottom Water in the Australian Antarctic Basin
复制标题
DOI：
10.1002/2013gl058921
复制
发表时间：
2014-03-16
影响因子：
5.2
通讯作者：
Rintoul, Stephen R.
中科院分区：
文献类型：
--
作者：
van Wijk, Esmee M.;Rintoul, Stephen R.
自20世纪60年代末以来，澳大利亚南极海盆的南极底层水（AABW）变得更淡且更轻，在南极底层水的源头附近观测到的变化最大。1969 - 1971年至2008 - 2012年间，中性密度（γₙ）>28.30 kg/m³的南极底层水体积减少了50%，以每十年>100米的速度变薄。在1995年之前，密集的南极底层水的收缩主要由比γₙ = 28.15 kg/m³更轻的水的扩张所平衡，而在1995年之后则由密度较小的南极底层水类别膨胀所平衡。1995年至2011 - 2012年间，在最密集的南极底层水中氧浓度保持不变，对于γₙ>28.31 kg/m³的南极底层水，在中性面上氧浓度增加，这与在此期间持续的通风作用相符。南极底层水的位温、盐度、密度、体积和氧含量的观测变化可归因于源水变淡，但不能仅由形成速率的变化来解释。
要点
变淡导致南极底层水（AABW）收缩
自1970年以来，AABW已收缩约50%，且每十年变薄超过100米
等密度面上氧含量的小幅增加表明AABW持续通风
Antarctic Bottom Water (AABW) in the Australian Antarctic Basin has become fresher and lighter since the late 1960s, with largest changes observed near the sources of AABW. The volume of AABW with neutral density ((n))>28.30kgm(-3) decreased by 50% between 1969-1971 and 2008-2012, thinning at a rate of >100m per decade. Contraction of dense AABW was balanced primarily by expansion of water lighter than (n)=28.15kgm(-3) prior to 1995 and by inflation of less dense classes of AABW after 1995. Oxygen concentrations remained unchanged in the densest AABW and increased on neutral surfaces for AABW with (n)>28.31kgm(-3), between 1995 and 2011-2012, consistent with continued ventilation over this time period. The observed changes in potential temperature, salinity, density, volume, and oxygen of AABW can be accounted for by freshening of the source waters but cannot be explained by changes in formation rate alone.Key Points Freshening drives contraction of Antarctic Bottom Water (AABW) AABW has contracted by about 50% and thinned more than 100 m per decade since 1970 Small increase in oxygen on isopycnals suggests continued ventilation of AABW