Collaborative Research: Thermodynamic and Dynamic Drivers of the Arctic Sea Ice Mass Budget at MOSAiC

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Energy fluxes to the sea ice, and the processes that control them in time and space, comprise some of the largest uncertainties in current models of the central Arctic system and are likely changing as the sea ice thins. This project will make observations to provide the type of information that model developers need for representing emergent Arctic processes. These observations will be the first set of comprehensive, coupled atmosphere-ice-ocean energy and momentum flux measurements collected within a well-defined network. They will enable a process-based understanding of ice thermodynamics and dynamics via synergistic use of a coupled model. The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition is a tremendous opportunity to leverage large US and international investments MOSAiC is motivated by the changing Arctic system and declining sea ice, and their significant implications for the global climate system and numerous stakeholders. The initiative seeks to address leading deficiencies in model representation of coupled, atmosphere-ice-ocean processes in the Arctic system through intensive, year-round observations from a drifting station in the central Arctic and coordinated multi-scale modeling. This project will examine the detailed interplay of sea-ice thermodynamic and dynamic processes and how they control the state of the ice over a full year. This project will entail an observational array of five nodes installed at approximately 15 km separation in the central Arctic sea ice, each of which has systems to measure continuously the states of the upper ocean and lower atmosphere, the heat and momentum fluxes from the ocean and atmosphere to the ice, and the ice thermodynamic state and mass balance. A network of position buoys will be used to measure ice movement and deformation across the observing domain. Regional, coupled-system model simulations will provide the means to synthesize observational information towards process understanding. Together these tools will be used to build comprehensive sea ice energy, upper ocean heat, and sea-ice momentum budgets, examine how these co-vary in space and time over all seasons, and develop temporally-evolving process relationships among multiple key parameters. They will use the detailed observations and coupled regional model to examine how energy transfer processes (thermodynamics) are influenced by sea-ice deformation (dynamics) on sub-seasonal to seasonal time scales, and they will assess sea-ice predictability related to dynamic and thermodynamic process relationships, using a full year of quasi-operational, 10-day sea-ice forecasts. Improved predictive models are an important means for addressing major societal needs related to Arctic change and declining sea ice. The project will provide an observational and process-based foundation for model development that has been called for by model developers and international experts. Moreover, it will offer insight into the sources of sea ice predictability, which will help to constrain future research pathways for improved sea ice models. The observations will enable a wide array of coupled system research that reaches well beyond the proposed project to impact research on other aspects of the Arctic physical, biological, and biogeochemical systems. Moreover, this project will support development towards autonomous ocean and atmospheric flux measurements that will help fill critical gaps in the Arctic observing network. Educational content developed around the project's research themes will support student learning on the physics of the Arctic system and enable broader scientific outreach efforts.