Ice-Shelf Backpressure: Form Drag Versus Dynamic Drag

摘要: The traditional concept of ice-shelf backpressure, defined as the stress deficit reducing spreading rates below unconfined-expansion limit, is inadequate to predict regime at an ice-stream grounding line when flow geometry differs from ideal, rectangular channel flow. This inadequacy results action glaciostatic stresses distributed around margins ice shelf, which lead a reaction force, termed form drag, stream. Here, I examine West Antarctic Ice Sheet in terms drag and dynamic latter arises purely due motion viscous coupling shear margins. Finite-element simulations Ross Shelf discussed here show that dominates streams B C. As demonstration consequence this dominance, future evolution Shelf, C are simulated assess response impulsive removal Crary Rise. simulation shows forces restraining Stream do not change by significant amount even after 1000 years adjustment. C, however, reduce 40% over year period, with initial 25% occuring within first 250 years. contrast between attributed dominance its dependence on thickness distribution, effect Rise has lines two streams.