Community Talk: Jingwei Zhang (UTas)
The Response of the Southern Ocean to Climatological Iceberg Freshwater Forcing
Abstract
Antarctic icebergs, as a moving source of freshwater while drifting in the Southern Ocean, have been suggested to play a significant role in altering water masses and sea ice dynamics, especially during recent increases in Antarctic ice discharge. Most current climate models, however, misrepresent Antarctic iceberg melting by assuming it releases uniformly along the coast. In this study, we investigate the impacts of the climatological spatial distribution of iceberg melt on the Southern Ocean by implementing a recent simulation of iceberg melt pattern in a global ocean-sea ice model. Our results demonstrate that widespread iceberg melting leads to decreased surface salinity and enhanced stratification, which in turn suppresses vertical convection and mixing, ultimately leading to a reduction in upward heat transport. Such reduced heat transport results in an accumulation of heat in the subsurface and a cooling effect at the surface, further intensifying the formation of sea ice. Additionally, we emphasize the significance of incorporating a more realistic distribution of iceberg melt into ocean models, which can reduce model bias of climatological temperature and salinity by up to 30% compared with observations. Our results underscore the necessity of considering iceberg drifting patterns in climate/ocean models. Current models that neglect drifting icebergs must be interpreted based on the responses presented in this study.
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