Circulation and melting beneath George VI Ice Shelf, Antarctica
Circulation and melting beneath George VI Ice Shelf, Antarctica
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DOI：
10.1029/2007jc004449
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发表时间：
2008-04-12
影响因子：
3.6
通讯作者：
Jacobs, Stan
中科院分区：
文献类型：
--
作者：
Jenkins, Adrian;Jacobs, Stan
海洋学数据从东部别林斯高晋海，代表第一个近同期的采样条件附近的北方和南部的乔治六冰架冰锋。温度超过1摄氏度的绕极深水（CDW）淹没了整个大陆架，并形成了冰架下空腔的主要流入。我们使用的盐度，潜在的温度，稳定同位素比和溶解氧，氦，氖的测量表明，流出物中含有的浓度上升到最大值约3%的融水。假定海流处于地转平衡，我们计算了沿着冰锋断面的相对速度，然后通过反演示踪剂守恒方程估计绝对速度。我们得到的总平均融化速率为3-5 m a（-1），冰架下由南向北的净通流为0.17-0.27 Sv。平均融化速率超过了平衡所需的，与最近观察到的冰架变薄和退缩。融化冰架下的驱动器上升流约0.1西弗的总CDW到表面混合层在两个冰锋。单位面积冰架覆盖的有效垂直热通量为8 W m（-2），是通过邻近开阔水域主密度跃层垂直扩散估算的4倍多。南向北的通流携带一个特别强烈的签名上涌CDW，包括低溶解氧和高营养盐浓度，向北进入玛格丽特湾。
Oceanographic data are presented from the eastern Bellingshausen Sea, representing the first near-contemporaneous sampling of conditions near both the northern and southern ice fronts of George VI Ice Shelf. Circumpolar Deep Water (CDW) with a temperature in excess of 1 degrees C floods the entire continental shelf and forms the main inflow to the cavity beneath the ice shelf. We use measurements of salinity, potential temperature, stable isotope ratios and dissolved oxygen, helium, and neon to show that the outflows contain meltwater in concentrations that rise to a maximum of around 3%. Assuming that the currents are in geostrophic balance, we calculate relative velocities along the ice front sections, then estimate the absolute velocity by inversion of the tracer conservation equations. We obtain an overall mean melt rate of 3-5 m a(-1) and a net south-to-north throughflow beneath the ice shelf of 0.17-0.27 Sv. The mean melt rate exceeds that required for equilibrium, consistent with recent observations of ice shelf thinning and retreat. Melting beneath the ice shelf drives upwelling of about 0.1 Sv in total of CDW into the surface mixed layer at the two ice fronts. The effective vertical heat flux per unit area of ice shelf cover is 8 W m(-2), more than 4 times that estimated for vertical diffusion through the main pycnocline of the neighboring open water region. The south-to-north throughflow carries a particularly strong signature of upwelled CDW, including low dissolved oxygen and high nutrient concentrations, north into Marguerite Bay.