Formation and export of dense shelf water from the Adélie Depression, East Antarctica
Formation and export of dense shelf water from the Adélie Depression, East Antarctica
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DOI：
10.1029/2007jc004346
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发表时间：
2008-04
影响因子：
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通讯作者：
G. Williams;N. Bindoff;S. Marsland;S. Rintoul
中科院分区：
文献类型：
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作者：
G. Williams;N. Bindoff;S. Marsland;S. Rintoul
[1] 阿德利洼地的沿岸浅滩区是澳大利亚 - 南极盆地南极底层水的重要来源。我们展示了来自温度 - 盐度传感器的数据时间序列（1998年4月至1999年5月以及1999年8月至2000年2月），这些数据来自阿德利洼地以及已知的阿德利海槛流出区域，用于描述陆架水密度的年循环。从4月到9月，浅滩区下方的盐化作用产生了高密度的陆架水。在9月 - 10月期间，洼地中的陆架水密度达到峰值，为27.94千克/立方米，并且在布坎南湾以北观测到冰架水冷却和变淡的特征。在11月 - 12月，随着温暖且相对较淡的变性绕极深层水侵入阿德利海槛以东，陆架水密度降低。从1月 - 3月，表层受到大气冷却的影响，这使得上层水体发生翻转。在阿德利海槛处，观测到的日平均海流约为10厘米/秒，在海槛深度处的瞬时强流大于50厘米/秒。利用一个具有矩形横截面积（6×10⁶平方米）的理想化流出区域，我们首次按位势密度等级对陆架水输出进行了估算。假设最小密度为27.88千克/立方米的陆架水具有足够的负浮力用于下坡混合，并且由于卷入作用体积增加四倍（1:3混合比），那么0.1 - 0.5 Sv的高密度陆架水输出导致该区域底层水的年平均产量在0.4 - 2.0 Sv之间。底层水估算值的较大范围是由于数据限制，要缩小这个范围需要进一步的系泊观测。
[1] Coastal polynyas in the Adelie Depression are an important source of Antarctic Bottom Water to the Australian-Antarctic Basin. We present time series (April 1998 to May 1999 and August 1999 to February 2000) of data from temperature-salinity sensors, in both the Adelie Depression and the known outflow region of the Adelie Sill, to describe the annual cycle of shelf water densities. From April through September, salinification beneath the polynya produces dense shelf waters. During September–October, shelf water densities in the depression peak at 27.94 kg m−3, and the cooling and freshening signature of Ice Shelf Water is observed north of Buchanan Bay. In November–December, shelf water densities decrease as intrusions of warm and relatively fresh modified Circumpolar Deep Water enter east of the Adelie Sill. From January–March the surface layer is conditioned by the cooling of the atmosphere, which overturns the upper water column. At the Adelie Sill, observed daily mean currents were approximately 10 cm s−1 with intense instantaneous currents greater than 50 cm s−1 at the sill depth. Using an idealized outflow region with a rectangular cross-sectional area (6 × 106 m2), we present the first estimates of shelf water export by potential density class. Assuming shelf water with a minimum density of 27.88 kg m−3 has sufficient negative buoyancy for downslope mixing and a fourfold volume increase (1:3 mixing ratio) from entrainment, the dense shelf water export of 0.1–0.5 Sv results in an annual average production of bottom water in this region of between 0.4 and 2.0 Sv. The wide range in bottom water estimate results from data limitations, and a narrowing of this range requires further mooring observations.