Issues in large-scale sea ice dynamics modeling

Capabilities to model sea ice dynamics have grown substantially over the last few years. As a result, users now face many decisions when choosing an appropriate mathematical model for a specific application. Models share the purpose of simulating ice motion, but on different time and space scales. Although development of these models has been aimed at different applications, models do appear to be reaching a stage of maturity where they have many common features. In this review, we examine various application needs, and describe the range of important features available in a variety of geophysical scale ice behavior models, to enable the user to make an intelligent model choice. The range of applications requiring choice of a model by the user may widely vary. For instance, a great amount of uncertainty in motions of the sea ice cover makes modeling of general scientific interest. To gain basic scientific understanding of the behavior of sea ice requires knowledge of all external forces as well as the constitutive relationship between internal stress and deformations and therefore models are helpful. These motions are also of engineering importance because of ongoing petroleum development along the North Slope of Alaska. Ice motions are of direct importance, because oil spilled in the ice would be transported by the motion of the ice cover. The geophysical scale forces from winds and currents over wide areas of the ice pack cause motion which can be transmitted over large distances when internal ice stress is large. The ice stress transmitted shoreward can generate forces on any drilling structures positioned there. On scales of a hundred meters and less these forces affect the design and use of these offshore drilling structures. Artificial islands, docks and breakwaters, and conical platforms must therefore be designed to withstand the forces that sea ice can apply. Other engineering and operational applications include warning of possible ice invasions during petroleum drilling operations in open water conditions. Also at scales of hundreds of kilometers resolution, sea ice behavior affects climate dynamics, where the effects of sea ice motion and deformation are felt primarily through the generation of open water that increases heat transfer from the atmosphere to the ocean. Here, ice stress is not of direct physical concern. Ice stress does, however, play a role in estimating noise generated by the ice cover, still another possible application for an ice motion model.