Dynamics of the Bonney Coast Upwelling: insights from hourly Himawari-8 satellite imagery

Mr Aero Leplastrier1, Dr Zhi Huang1

1Geoscience Australia, Canberra, Australia

Abstract

The Bonney Coast Upwelling (BCU) is recognised as a KEF in the Australian marine area, due to its influence on pelagic productivity and biodiversity. Located along the southeast coast of South Australia, the BCU is a wind-driven system that operates intermittently throughout the austral summer. The upwelling has been investigated previously using a range of physical oceanographic techniques, from shipboard sampling to modelling and remote sensing. The application of remote sensing, however, has been limited by the temporal frequency of the MODIS and AVHRR satellite passes over the Australasian region (twice a day) making data susceptible to cloud contamination. This study utilised hourly images from the Himawari-8 geostationary satellite to generate daily sea surface temperature composites and applied a topographical position index method to isolate the signatures of the BCU. With the BCU mapped on a daily basis, we are able for the first time to quantitatively investigate the development of the BCU, from onset to termination, during an entire upwelling season. The initial analysis covered the period November 2016 – April 2017, and identified three distinct upwelling events (4–17 January, 19 January – 2 February, and 6 February – 31 March). At maximum development, these three events covered areas ranging between 10,052 and 25,253 km². The upwelling events showed rapid development with the spatial extent of the surface plume increasing by up to 10-fold within the first 48 hours. Connectivity between the BCU and other local upwelling features off Kangaroo Island and the Eyre Peninsula will also be discussed.

Biography

Aero graduated from the Australian National University in 2015 from the Research School of Earth Science with first class honours and a University Medal. He Joined Geoscience Australia at the start of this year as part of a graduate programme and will be continuing on in the marine section of the agency.

About the Association

The Australian Coastal Society (ACS) was initiated at the Coast to Coast Conference in Tasmania in 2004. The idea was floated as a means for those interested in coastal matters to communicate between conferences and where possible take resolutions of the conference to appropriate levels of government.

The idea was discussed further at the Coast to Coast Conference in Melbourne in 2006 and it was agreed that Bruce Thom develop a constitution of a company limited by guarantee that would operate on a national basis.

This plan was accomplished and in 2008 at the Coast to Coast Conference in Darwin the constitution was ratified and an Executive appointed. The company received charitable status in 2011.

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