Modeling interannual dense shelf water export in the region of the Mertz Glacier Tongue (1992–2007)
Modeling interannual dense shelf water export in the region of the Mertz Glacier Tongue (1992–2007)
复制标题
模拟默茨冰川舌地区的年际密集陆架水输出（1992-2007）
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
B. Legrésy
中科院分区：
文献类型：
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作者：
E. Cougnon;B. Galton;A. Meijers;B. Legrésy
澳大利亚-南极海盆周围的海洋观测表明，默茨冰川舌（MGT）附近的沿海潜热冰穴对密集陆架水（DSW）和相关的南极底层水（AABW）的形成具有重要意义。在这里，我们使用一个区域海洋/冰架模型，调查从1992年至2007年的Adelie（西部的MGT）和默茨（东部的MGT）凹陷的DSW出口的年际变化。模型的可变性是由观测到的地表热量和盐通量的变化驱动的。该模型模拟了DSW通过Adelie槛的年平均输出量约为0.070.06 Sv。从1992年到1998年，通过Adelie（Mertz）窗台出口的DSW在7月至11月期间达到0.14 Sv（0.29 Sv）的峰值。在平均到强烈的冰间湖活动期间（由表面海洋热损失定义），在阿德利低压形成的DSW可以通过MGT下的空腔传播到默茨低压。一个额外的模拟，海洋/冰架热力学已被禁用，突出了这样一个事实，即没有海洋/冰架相互作用过程的模型将显着高估率DSW出口。MGT的融化速率为1.20.4 m/年（-1）在平均到强冰间湖活动期间，并可增加到3.81.5 m/年在持续的弱冰间湖活动期间，由于相对温暖的水与冰架底部相互作用的存在增加。在弱冰间湖状态期间，MGT的熔化增加可导致DSW的进一步清新化，并最终限制AABW的产生。
Ocean observations around the Australian-Antarctic basin show the importance of coastal latent heat polynyas near the Mertz Glacier Tongue (MGT) to the formation of Dense Shelf Water (DSW) and associated Antarctic Bottom Water (AABW). Here, we use a regional ocean/ice shelf model to investigate the interannual variability of the export of DSW from the Adelie (west of the MGT) and the Mertz (east of the MGT) depressions from 1992 to 2007. The variability in the model is driven by changes in observed surface heat and salt fluxes. The model simulates an annual mean export of DSW through the Adelie sill of about 0.070.06 Sv. From 1992 to 1998, the export of DSW through the Adelie (Mertz) sills peaked at 0.14 Sv (0.29 Sv) during July to November. During periods of mean to strong polynya activity (defined by the surface ocean heat loss), DSW formed in the Adelie depression can spread into the Mertz depression via the cavity under the MGT. An additional simulation, where ocean/ice shelf thermodynamics have been disabled, highlights the fact that models without ocean/ice shelf interaction processes will significantly overestimate rates of DSW export. The melt rates of the MGT are 1.20.4 m yr(-1) during periods of average to strong polynya activity and can increase to 3.81.5 m/yr during periods of sustained weak polynya activity, due to the increased presence of relatively warmer water interacting with the base of the ice shelf. The increased melting of the MGT during a weak polynya state can cause further freshening of the DSW and ultimately limits the production of AABW.