AGU study reveals Antarctic Bottom Water moves north via two pathways

LinkedIn +

Researchers in a new study, published in the AGU’s Geophysical Research Letters, used a numerical simulation of Earth’s oceans to investigate the movement of Antarctic Bottom Water (AABW), discovering that it moves via two distinct pathways (“conduits”) from its four principal source areas northward.

This study, named How Does Antarctic Bottom Water Cross the Southern Ocean?, also found that the geographical boundaries between the water’s conduits occur near seafloor ridges, and little AABW exchange occurs across them. Circulation pathways within each conduit blend together AABW formed in two of the four main formation regions and export them to different oceans. Identification of these pathways elucidates the origin of observed trends in AABW properties and helps to predict where these changes may propagate in the coming decades.

Cooling, ice formation and mixing near Antarctica create dense ocean waters, known as Antarctic Bottom Water, which is derived from dense water that forms in several distinct Antarctic shelf regions. Due to their high density, these waters sink and propagate northward to fill the deepest parts of the Southern, Indian, Pacific and Atlantic Oceans.

Previous modeling studies have reached conflicting conclusions regarding export pathways of AABW across the Southern Ocean and the degree to which AABW originating from distinct source regions are blended during their export. This study addressed these questions using passive tracer deployments in a 61-year global high-resolution (0.1°) ocean/sea-ice simulation. Two distinct export “conduits” were identified – Weddell Sea- and Prydz Bay-sourced AABW are blended together and exported mainly to the Atlantic and Indian Oceans, while Ross Sea- and Adelie Land-sourced AABW are exported mainly to the Pacific Ocean.

Northward transportation of each tracer occurs almost exclusively (>90%) within a single conduit. These findings imply that regional changes in AABW production may impact the three-dimensional structure of the global overturning circulation. Hence AABW export has a significant and near-global impact on deep-ocean circulation and the distribution of physical properties (e.g., salinity, temperature, dissolved oxygen).

Share this story:

About Author

mm
, web editor

As the latest addition to the UKi Media & Events team, Elizabeth brings research skills from her English degree to her keen interest in the meteorological and transportation industries. Having taken the lead in student and startup publications, she has gained experience in editing online and print titles on a wide variety of topics. In her current role as Editorial Assistant, Elizabeth will create new and topical content on the pioneering technologies in transportation, logistics and meteorology.

Comments are closed.