Ice Shelf Ocean Research Articles

Computing marine-ice thickness at an ice-shelf base

AbstractThe freezing of sea water to the base of an ice shelf can give rise to large patches of accumulated ice, a phenomenon known as marine ice. In this study a numerical method is presented for calculating the thickness of the marine-ice layer using an ice- shelf-ocean model. The present-day modeling paradigm of ice-shelf–ocean interaction usually involves the fixed specification of the ice-shelf geometry while the ocean circulation in the cavity beneath the ice shelf evolves freely. This approach relies on several assumptions, such as steady-state ice-shelf thickness and ice-shelf flow fields, in order to make reasonable quantitative estimates of the thermodynamic exchange processes occurring at the ice-shelf base. This paper discusses the impact of these and other assumptions on the estimation of the thickness of the marine-ice layer. Model simulation results are presented for an idealized ice-shelf–ocean configuration as a demonstration of the feasibility of the numerical method. A sensitivity analysis is given so as to quantify the relative uncertainty in the marine-ice thickness that arises from uncertainties in the model input parameters, these being principally the ice-shelf flow field, the basal accumulation rate and the ice-shelf thickness field.

Adaptation of an Isopycnic Coordinate Ocean Model for the Study of Circulation beneath Ice Shelves

Abstract Much of the Antarctic coastline comprises large, floating ice shelves, beneath which waters from the open ocean circulate. The interaction of the seawater with the base of these ice shelves has a bearing both on the rate at which Antarctic Bottom Water is formed and on the mass balance of the ice sheet. An isopycnic coordinate ocean general circulation model has been modified so as to allow the incorporation of a floating ice shelf as an upper boundary to the model domain. The modified code admits the introduction of an arbitrary surface pressure field and includes new algorithms for the diagnosis of entrainment into, and detrainment from, the surface mixed layer. Special care is needed in handling the cases where the mixed layer, and isopycnic interior layers, interact with surface and basal topography. The modified model is described in detail and then applied to an idealized ice shelf–ocean geometry. Simple tests with zero surface buoyancy forcing indicate that the introduction of the static s...

Temperature field of an ice shelf in the vicinity of a hot water-drilled well

The temperature of an ice shelf following open thermic drilling is investigated. The time dependence of the ice temperature and the profile of its lower surface are analyzed. The time of relaxation of the system ocean—ice shelf—atmosphere to the equilibrium state is estimated. The results are used to substantiate the use of data on the dynamics of the lower surface of an ice shelf in monitoring of global temperature of the ocean.