Modeling the Impact of Icebergs on the Southern Ocean Freshwater Budget and Circulation

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ABSTRACTOCE-0350912Icebergs released from the Antarctic Ice Sheet are dispersed by the winds and ocean currents, ultimately melting and accounting for up to 30 percent of the freshwater input to the Southern Ocean. In the absence of comprehensive observational estimates of long-term iceberg calving fluxes, oceanic distribution and dissolution, the investigation of icebergs in the Southern Ocean is limited to indirect estimates, and theoretical and computational models of iceberg processes. This study, will develop a model of the complex land ice-iceberg-sea ice-ocean, validate it against glaciological and oceanographic observations, and run with it climatic change and variability scenarios. Off-the-shelf models of the land ice, sea ice, and ocean components will be combined with a novel formulation for iceberg transport. A computationally efficient Eulerian approach based on the calculation of a time-dependent distribution function for iceberg size will be used instead of the more common Lagrangian iceberg models which require far more computational overhead. Such a distribution function conveys information on the probability of finding icebergs of a predetermined size at a given point in space and time, without the need of tracking each of them independently. A 1-km-resolution, "iceberg-resolving" model will also be used to reproduce the evolution of the giant iceberg B-15 across the Ross Sea from 2000 till today. Analysis of the experimental results will help to improve existing parameterizations of the iceberg momentum balance and the development of new ones if necessary.Broader impacts will include improved iceberg parameterization for present-day and paleoclimate studies. With close collaboration with the Oceanography Section of NCAR, the iceberg model will be incorporated into the Community Climate System Model. A summer undergraduate student will be trained and introduced to current problems in ocean and climate dynamics. A high school student will be mentored within the scope of this project to participate in the Intel Science Talent Search competition.