Slope exchange processes in the Weddell and Amundsen Seas

Do Valle Chagas Azaneu, Marina (2019) Slope exchange processes in the Weddell and Amundsen Seas. Doctoral thesis, University of East Anglia.

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Abstract

This thesis aims to investigate the dynamical processes of the along-slope currents in the Weddell and Amundsen Seas (Antarctica), their variability and the mechanisms that regulate the cross-slope exchange of properties. Firstly, this thesis explores the short-term and spatial variability of the Antarctic Slope Front system at the northwestern Weddell Sea using data from three ocean gliders. Twenty-two sections along the eastern Antarctic Peninsula are grouped regionally and composited by isobaths. The along-slope transport of the Antarctic Slope Current (upper 1000 m) varies between 0.2 and 5.9 Sv. Higher eddy kinetic energy (0.003m2s¡2) is observed on sections where dense water is present, possibly due to baroclinic instabilities in the deep layer. These results provide some of the first observational confirmation of the high frequency variability associated with an active eddy field that has been suggested by recent numerical simulations in this region. Using a multidisciplinary dataset, the physical processes associated with phytoplankton biomass distribution and how these relate to frontal processes east of the Antarctic Peninsula are assessed. There is a distinction between upperslope and off-shelf areas, which are likely disassociated from each other. Over the shelf, the relatively low stratification and the likely enhanced mixing and nutrient input from sediments would contribute to the relatively high primary production. Offshore, the stronger pycnocline and passive sinking of phytoplankton creates a deeper subsurface chlorophyll maximum. Finally, observations from moorings and from ship-based hydrographic stations at eastern Amundsen Sea are analysed to investigate the variability of the slope undercurrent and the Circumpolar Deep Water layer within troughs at the continental shelf. The cumulative onshore temperature transport of CDW was 1.21 TW and 1.79 TW at the central and eastern trough, respectively. High-frequency variability of temperature transport estimates are different among shelf-breakmoorings; eddies and coastal-trapped waves are likely contributors.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Environmental Sciences
Depositing User:	Stacey Armes
Date Deposited:	12 Apr 2019 12:00
Last Modified:	12 Apr 2019 12:00
URI:	https://ueaeprints.uea.ac.uk/id/eprint/70550
DOI:

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