A numerical model of interactions between a marine ice sheet and the solid earth: Application to a West Antarctic ice stream
A numerical model of interactions between a marine ice sheet and the solid earth: Application to a West Antarctic ice stream
复制标题
海洋冰盖与固体地球之间相互作用的数值模型：在南极西部冰流中的应用
DOI：
10.1029/jc090ic01p01100
复制
发表时间：
1985
影响因子：
--
通讯作者：
J. A. Clark
中科院分区：
文献类型：
--
作者：
C. Lingle;J. A. Clark
建立了一个时间相关的数值模型，模拟了全新世海平面上升时期西南极冰架边缘的冰流退缩。本文介绍了一种计算冰流后退过程中冰和水荷载变化引起的固体土变形的方法。在冰流模型中加入了地球变形引起的相对海平面变化作为反馈机制。当假定冰流位于刚性地面上时，由于冰流及其集水区变薄而引起的地球的弹性和粘性隆起会延迟接地线相对于计算后退的速度。据计算，在公元前15000年，由于海平面上升，接地线的撤退开始得非常缓慢。在大约30公里后，在13000 b.p.，由于水深增加和海床向冰盖内部倾斜，退缩加速了。到公元前8000年，地球变形的反馈效应导致接地线的后退延迟了大约1000年，相对于在刚性地球上计算的后退。由于接地线上的隆起部分抵消了水深增加的影响，因此弹性和粘性土响应对计算的后退率有一定的调节作用。计算出的接地线后退速度变慢，并逐渐停止在冰流接地线当前位置附近。相对于在刚性地球上计算的后退，海底的隆起使总后退距离减少了80公里。在距今3000年前到现在之间，由于持续的粘性隆起导致海洋深度下降，接地线向前推进了20公里。正如早期的调查人员所指出的那样，来自罗斯冰架的阻力被发现对阻止罗斯海湾的接地线后退起着至关重要的作用。在给定冰架后退历史的背景下，地球变形的反馈效应导致接地线后退速率的减小，计算的总后退距离的减小，以及海平面上升停止后接地线的前进。
A time-dependent numerical model has been constructed that simulates retreat of a West Antarctic ice stream from the edge of the continental shelf during the Holocene period of rising sea level. This paper describes a method for computing the deformation of the solid earth caused by changes in ice and water loading during retreat of the ice stream. The relative sea level changes caused by earth deformation are incorporated as a feedback mechanism in the ice stream model. Elastic and viscous uplift of the earth, caused by thinning of the ice stream and its catchment area, is found to delay retreat of the grounding line relative to computed retreat when the ice stream was assumed to be resting on a rigid earth. Computed retreat of the grounding line began very slowly, at 15,000 B.P., because of rising eustatic sea level. Retreat accelerated after about 30 km, at 13,000 B.P., because of increasing water depth and a seabed sloping down toward the ice sheet interior. By 8000 B.P. the feedback effects of earth deformation caused retreat of the grounding line to be delayed by about 1000 years, relative to computed retreat on a rigid earth. The elastic and viscous earth response exerted a moderating influence on the computed retreat rate because uplift at the grounding line partially counteracted the effect of increasing water depth. Computed retreat of the grounding line slowed, and gradually stopped, near the present position of the ice stream grounding line. Uplift of the seafloor caused the total retreat distance to be reduced by 80 km relative to retreat computed on a rigid earth. A readvance of 20 km of the grounding line occurred between 3000 B.P. and the present because continuing viscous uplift caused sea depth to decrease. Resistance from the Ross Ice Shelf was found to be of primary importance in bringing retreat of the grounding line to a stop in the Ross Embayment, as suggested by earlier investigators. Within the context of a given ice shelf retreat history the feedback effects of earth deformation caused a reduction of the grounding-line retreat rate, a reduction of the total computed retreat distance, and a readvance of the grounding line after eustatic sea level stopped rising.