Combining physics-based and statistics-based approaches to model calving in Antarctica

Abstract

Surface and basal crevasses are deep fractures in ice that are observed on the surface and the base of the Antarctic ice sheet/ice shelves, respectively. They are a direct pre- cursor of formation of rifts in ice shelves and a consequent calving or breaking off of icebergs. Modelling of calving is crucial for better estimation of the ice mass balance in Antarctica because ice shelves act like a supporting mechanism for the inland ice preventing it from accelerating into the ocean. While there have been a number of studies that attempted to parameterise calving, each of them has limitations that do not allow to apply them to all the Antarctic ice shelves on a large scale. A more comprehensive calving model needs to include not only parameterisation of calving at ice fronts, but also the history of fracturing of the ice that led to a calving event such as formation, advection and propagation of both surface and basal crevasses. Towards improving a calving parameterisation in ice sheet models we constructed a set of sub-models for predicting surface and basal fracturing, vertical and horizontal propagation as well as advection. Combining statistics-based and physics-based ap- proachers we developed a preliminary calving model that includes the full history of rifts and crevasses, from their initiation to the final break off at the ice front.