A new model for the Marginal Ice Zone (MIZMAS)

The marginal ice zone (MIZ) is generally defined as a transition region from open water to pack ice with changing concentration, thickness, and ice floe sizes and shapes. The state of sea ice in the MIZ is currently modeled by an ice thickness distribution (ITD) that provides no information on the geometry of the ice pack, i.e., no description of the floe size distribution (FSD). This is not optimal, given that the FSD impacts ice strength and roughness, ice melt and growth, air–sea fluxes, and surface wave propagation. The FSD is in turn influenced by many of these processes.

Towards a prognostic description of Floe Size Distribution

At present, most ITD-based modeling of Arctic Ocean sea ice has focused on the large-scale climate response to changing winds and thermodynamic forcing, with relatively little attention paid to the special physics found in the MIZ. At the same time, there is a body of literature on floe dynamics that is largely theoretical or applied only to simple models. What is needed now is to combine the results of these two fields into a full model of the arctic sea ice pack including the MIZ which includes both ITD and FSD, validated with new MIZ observations. This will be especially exciting when applied to the Chukchi and Beaufort MIZ (CBSMIZ), where rapid transformation has occurred in recent years in response to arctic warming and changing atmospheric and oceanic circulation.

The overarching goal of this project is to enhance our understanding of MIZ processes and interactions, and to strengthen our prediction capability of future climate change, particularly the changes in both the ITD and the FSD, in the CBS. We propose numerical investigations of the historical and contemporary changes in the sea ice and upper ocean of the CBSMIZ. We also plan to investigate future changes of the CBSMIZ under global warming scenarios. These investigations involve new and potentially transformative theoretical and numerical work to develop, implement, and validate a new coupled ice–ocean Marginal Ice Zone Modeling and Assimilation System (MIZMAS) that will enhance the representation of the unique MIZ processes by incorporating a FSD and corresponding model improvements.

The development of MIZMAS will be based on systematic model parameterization, calibration, and validation, and data assimilation, taking advantage of the integrated observational and modeling efforts planned by the ONR MIZ DRI.