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Dense shelf water spreading from A ntarctic coastal polynyas to the deep S outhern O cean: A regional circumpolar model study
Author(s) -
Kusahara Kazuya,
Williams Guy D.,
Tamura Takeshi,
Massom Robert,
Hasumi Hiroyasu
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2017jc012911
Subject(s) - oceanography , circumpolar deep water , antarctic bottom water , ice shelf , geology , sea ice , continental shelf , water mass , tracer , thermohaline circulation , circumpolar star , climatology , north atlantic deep water , cryosphere , physics , nuclear physics
The spreading of dense shelf water (DSW) from Antarctic coastal margins to lower latitudes plays a vital role in the ocean thermohaline circulation and the global climate system. Through enhanced localized sea ice production in Antarctic coastal polynyas, cold and saline DSW is formed over the continental shelf regions as a precursor to Antarctic Bottom Water (AABW). However, the detailed fate of coastal DSW over the Southern Ocean is still unclear. Here we conduct extensive passive tracer experiments using a circumpolar ocean‐sea ice‐ice shelf model to investigate pathways of the regional polynya‐based DSW from the Antarctic margins to the deep Southern Ocean basins. In the numerical experiments, the Antarctic coastal margin is divided into nine regions, and a passive tracer is released from each region at the same rate as the local sea ice production. The modeled spatial distribution of the total concentration of the nine tracers is consistent with the observed AABW distribution and clearly demonstrates nine routes of the DSW over the Southern Ocean along its bottom topography. Furthermore, the model shows that while ∼50% of the total tracer is distributed northward from the continental shelf to the deep ocean, ∼7% is transported poleward beneath ice shelf cavities. The comprehensive tracer experiments allow us to estimate the contribution of local DSW to the total concentration along each of the pathways.