Submesoscale sea ice-ocean interactions in marginal ice zones

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Identifying critical processes governing marginal ice zone (MIZ) dynamics remains one of the key challenges in our ability to comprehend and accurately model the rapidly changing polar oceans. MIZs are regions of strong mixed layer gradients in ocean temperatures and salinities, indicating that enhanced ocean variability at relatively small spatial scales ought to be present there. However, quantitative estimates of the role of small scale flows in MIZ dynamics are currently missing, and climate models do not parameterize these non-linear processes. This research will test the hypothesis that energetic vertical velocities at relatively small scales can efficiently bring the oceanic heat in contact with the sea ice and affect its melt rates. The research is of critical importance to society for understanding how sea ice and ocean circulation evolve under modified surface forcing conditions in a changing climate. The research activity will develop a diverse and globally competitive STEM workforce by establishing interdisciplinary collaborations among several U.S. academic institutions and broadening participation of underrepresented groups. The project will primarily fund a post-doctoral scientist who will be trained with broad exposure to the fields of physical oceanography and remote sensing. The investigators will contribute to enhancing society's scientific and technological understanding by engaging in undergraduate and graduate teaching activities, mentoring summer undergraduate students and participating in high-school outreach activities.The project will use a submesoscale-permitting global ocean model together with a set of idealized numerical experiments to diagnose the characteristics of submesoscale flows in various MIZs, classify their generation mechanisms, and assess their cumulative impact on sea ice melt rates. Critical forcing will be identified by conducting hydrodynamic stability analysis and by evaluating MIZ processes driving the potential vorticity towards negative values characteristic of sub-mesoscale flows. An energy budget analysis will be explored to understand submesoscale sources and sinks, and reveal the role of sea ice-ocean drag in damping upper-ocean variability. A theoretical framework explaining sea ice velocity and concentration patterns will be developed and used together with satellite data to observationally constrain submesoscale vertical velocities in the ocean. The project implements a synergetic triad of high resolution numerical simulations, theory development, and observational data analysis, representing a timely and unique opportunity to transform our understanding of sea ice-ocean interactions in MIZs. The research will result in a global estimate of submesoscale sea ice-ocean heat fluxes and, supported by satellite observations of sea ice patterns in MIZs, provide a theoretical framework to identify oceanic and atmospheric conditions under which submesoscale heat fluxes prevail. The remote sensing component will unify observations from multiple satellites and create a novel set of two-dimensional observations of ocean vorticity at submesoscales that could be used to directly test and advance upper-ocean turbulence theories. Upon completion, this research project will advance our knowledge of submesoscale sea ice ocean interactions and reveal missing ocean-ice heat pathways; results will also improve future predictions of sea ice extent.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.