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Theses

On the lifecycle of Antarctic Bottom Water

Abstract : Antarctic Bottom Water is the most voluminous water mass of the World Ocean, and it feeds the deepest and slowest component of ocean circulation. The processes that govern its lifecycle are therefore key to the ocean's carbon and heat storage capacity on centennial to multi-millennial timescales. This thesis aims at characterizing and quantifying processes responsible for the destruction (synonymous of lightening and upwelling) of Antarctic Bottom Water in the abyssal ocean. Using an observational estimate of the global ocean thermohaline structure and diagnostics based on the density budget of deep waters, we explore the roles of basin geometry, geothermal heating and mixing by breaking internal waves for the abyssal circulation. We show that the shape of ocean basins largely controls the structure of abyssal upwelling. The contribution of mixing powered by breaking internal waves, though poorly constrained, is estimated to be insufficient to destroy Antarctic Bottom Water at a rate comparable to that of its formation. Geothermal heating plays an important role for the upwelling of waters covering large seafloor areas. The results suggest a reappraisal of the role of mixing in deep straits and sills, but also of the fundamental role of basin geometry, for the lightening and transport of abyssal waters.
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  • HAL Id : tel-01592475, version 1

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Casimir de Lavergne. On the lifecycle of Antarctic Bottom Water. Oceanography. Université Pierre et Marie Curie - Paris VI, 2016. English. ⟨NNT : 2016PA066373⟩. ⟨tel-01592475⟩

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