Adjoint sensitivities of sub-ice-shelf melt rates to ocean circulation under the Pine Island Ice Shelf, West Antarctica
Adjoint sensitivities of sub-ice-shelf melt rates to ocean circulation under the Pine Island Ice Shelf, West Antarctica
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DOI：
10.3189/2012/aog60a025
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发表时间：
2012-01-01
影响因子：
2.9
通讯作者：
Losch, Martin
中科院分区：
文献类型：
--
作者：
Heimbach, Patrick;Losch, Martin
我们调查的敏感性下，松岛冰架，西南极洲，在海洋状态的变化，使用伴随的海洋模式，是能够代表流动的冰架腔。伴随码是基于马萨诸塞州理工学院的海洋环流模型（MITgcm）的算法微分（AD）。伴随模型扩展到AD过程中添加相应的子冰架腔代码，实现了三方程热力学融化率参数化，推断热量和淡水通量在冰架/海洋边界。推断的敏感性揭示了主导的时间尺度为30 - 60天的货架出口连接到深层内部通过平流过程。他们表现出丰富的三维时间演变的模式，可以理解的组合的浮力强迫流入的水团，空腔的几何形状和效果的旋转和地形在引导流动的存在下，在基岩测深的突出特点。主要的敏感性途径被发现超过一个门槛，以及“阴影区”的非常低的敏感性。就这些短暂模式的可靠性而言，它们为观测部署和监测方面的决策提供了重要信息。
We investigate the sensitivity of sub-ice-shelf melt rates under Pine Island Ice Shelf, West Antarctica, to changes in the oceanic state using an adjoint ocean model that is capable of representing the flow in sub-ice-shelf cavities. The adjoint code is based on algorithmic differentiation (AD) of the Massachusetts Institute of Technology's ocean general circulation model (MITgcm). The adjoint model was extended by adding into the AD process the corresponding sub-ice-shelf cavity code, which implements a three-equation thermodynamic melt-rate parameterization to infer heat and freshwater fluxes at the ice-shelf/ocean boundary. The inferred sensitivities reveal dominant timescales of 30 60 days over which the shelf exit is connected to the deep interior via advective processes. They exhibit rich three-dimensional time-evolving patterns that can be understood in terms of a combination of the buoyancy forcing by inflowing water masses, the cavity geometry and the effect of rotation and topography in steering the flow in the presence of prominent features in the bedrock bathymetry. Dominant sensitivity pathways are found over a sill, as well as 'shadow regions' of very low sensitivities. To the extent that these transient patterns are robust they carry important information for decision-making in observation deployment and monitoring.