A Finite-Element Model of Basal Water Generated by Melting in an Ice Sheet Model

It is well known that water is produced at the bed of an ice sheet when the temperature of the bed reaches the pressure melting point. The current ice sheet model, with its ability to calculate temperatures throughout the ice sheet, is also able to calculate melt rates at the bed. By incorporating a model of the continuity equation for the basal-water flow, this project will attempt to follow the movement of this water under the ice sheet as it flows from source regions to sink regions. The ability to predict wet-based regions is important to the understanding of the occurrence of the sliding mechanism, which is thought to control ice stream dynamics. The primary task will be to ascribe physical meaning to the parameters of the basal-water continuity equation. This will involve extracting, from observational evidence, the laws governing the flow of subglacial water. These will need to capture the essence of the underlying physics and yet remain simple enough to be treatable within the discretized and generalized snapshot of reality provided by numerical simulations. The primary effort will focus on compiling and analyzing the existing observational and theoretical constraints on ice-sheet hydrology. These data will be used to evaluate which modes of subglacial water flow are the most important and what values of parameters must be used to best incorporate the subglacial processes into the ice sheet model.