A synchronously coupled global model iOM4: a new modeling tool for simulations of the ocean-cryosphere interactions

Recent model developments have allowed to account for the effect of the Antarctic Ice Sheet in the Earth System Models (ESMs). Thus far, coupling between an ice-sheet model and other model components of an ESM is performed off-line, and the exchange of the relative fields is done once a year. However, decades of remote sensing and in situ observations show that there is a tight couplingbetween the Southern Ocean, sea ice and Antarctic Ice Sheet on a variety of temporal scales,including seasonal and subseasonal. Interactions between theocean, sea ice and ice sheet give rise to a number of feedbacks in this tightly coupled system. Investigations of such interactions and feedbacks require modeling tools capable of representing tight coupling between all three components. In order to be able to accurately simulate these interactions, investigate feedbacks and mutual impacts of these components, we have developed a synchronously coupled global ocean-cryosphere model iOM4. In this model, a global ocean-circulation model MOM6, an ice-sheet model MOM6-IS, which is a component of MOM6, and a sea-ice model SIS2, share the same horizontal grid; this ensures a tight coupling between the ice shelves and ocean circulation in the cavity. As a demonstration of the coupled-model capabilities, we perform global simulations using JRA-55 reanalysis as the atmosphericforcing for MOM6 and SIS2 and the output of simulations of the regional model MAR forced with JRA-55 for MOM6-IS.