Details

Autor(en) / Beteiligte

• Ribbat, Nina
• Roughan, Moninya
• Powell, Brian
• Rao, Shivanesh
• Kerry, Colette Gabrielle
• Dias, João Miguel

Titel

Transport variability over the Hawkesbury Shelf (31.5-34.5°S) driven by the East Australian Current

Ist Teil von

• PloS one, 2020-11, Vol.15 (11), p.e0241622-e0241622

Ort / Verlag

United States: Public Library of Science

Erscheinungsjahr

2020

Quelle

MEDLINE

Beschreibungen/Notizen

• The Hawkesbury Bioregion located off southeastern Australia (31.5-34.5oS) is a region of highly variable circulation. The region spans the typical separation point of the East Australian Current (EAC), the western boundary current that dominates the flow along the coast of SE Australia. It lies adjacent to a known ocean warming hotspot in the Tasman Sea, and is a region of high productivity. However, we have limited understanding of the circulation, temperature regimes and shelf transport in this region, and the drivers of variability. We configure a high resolution (750m) numerical model for the Hawkesbury Shelf region nested inside 2 data assimilating models of decreasing resolution, to obtain the best estimate of the shelf circulation and transport over a 2-yr period (2012-2013). Here we show that the transport is driven by the mesoscale EAC circulation that strengthens in summer and is related to the separation of the EAC jet from the coast. Transport estimates show strong offshore export is a maximum between 32-33oS. Median offshore transports range 2.5-8.4Sv seasonally and are a maximum during in summer driven by the separation of the EAC jet from the coast. The transport is more variable downstream of the EAC separation, driven by the EAC eddy field. Onshore transport occurs more frequently off Sydney 33.5-34.5oS; seasonal medians range -1.7 to 2.3Sv, with an onshore maximum in winter. The region is biologically productive, and it is a known white shark nursery area despite the dominance of the oligotrophic western boundary current. Hence an understanding of the drivers of circulation and cross-shelf exchange is important.