This paper examines the effect of basal topography and strength on the grounding-line position, flux and stability of rapidly-sliding ice streams. It does so by supposing that the buoyancy of the ice stream is small, and of the same order as the longitudinal stress gradient. Making this scaling assumption makes the role of the basal gradient and accumulation rate explicit in the lowest order expression for the ice flux at the grounding line and also provides the transcendental equation for the grounding-line position. It also introduces into the stability condition terms in the basal curvature and accumulation-rate gradient. These expressions revert to well-established expressions in circumstances in which the thickness gradient is large at the grounding line, a result which is shown to be the consequence of the non-linearity of the flow. The behaviour of the grounding-line flux is illustrated for a range of bed topographies and strengths. We show that, when bed topography at a horizontal scale of several tens of ice thicknesses is present, the grounding-line flux and stability have more complex dependencies on bed gradient than that associated with the ‘marine ice-sheet instability hypothesis’, and that unstable grounding-line positions can occur on prograde beds as well as stable positions on retrograde beds.

中文翻译：

---

床地形和海洋冰盖稳定性

本文研究了基础地形和强度对快速滑动冰流的接地线位置、通量和稳定性的影响。它是通过假设冰流的浮力很小，并且与纵向应力梯度相同的数量级来实现的。做出这种比例假设使得基础梯度和积累率的作用在接地线冰通量的最低阶表达式中明确，并且还提供了接地线位置的超越方程。它还在基础曲率和累积率梯度中引入了稳定条件项。在接地线处的厚度梯度较大的情况下，这些表达式恢复为公认的表达式，结果表明这是流动非线性的结果。接地线通量的行为针对一系列床形貌和强度进行了说明。我们表明，当存在几十个冰厚度的水平尺度的床地形时，接地线通量和稳定性对床梯度的依赖性比与“海洋冰盖不稳定假设”相关的更复杂，并且不稳定的接地线位置可能出现在顺行床上，也可能出现在逆行床上的稳定位置。