Evidence of a large seasonal coastal upwelling system along the southern shelf of Australia

• Published in: Geophysical research letters 2004-05, Vol.31 (9), p.L09310.1-n/a
• Main Authors: Kämpf, Jochen, Doubell, Mark, Griffin, David, Matthews, Roger L., Ward, Tim M.
• Format: Article
• Language: English
• Subjects: Earth, ocean, space; Exact sciences and technology; Marine
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2003GL019221

We report observational existence of a large seasonal coastal upwelling system that establishes in austral summer (December–April) along Australian southern shelves. Wind‐driven upwelling events occur simultaneously in three upwelling centres spanning a distance of ∼800 km. During each summer period there are ∼2–3 major upwelling events, each lasting ∼1 week. The simultaneous, rapid response of SST to wind forcing in the upwelling centres, which display vastly different shelf widths, points to the existence of a larger‐scale process that carries cold water onto the shelf prior to the upwelling season. Exploration of a major upwelling event in March 1998 shows the evolution of peak surface chlorophyll‐a concentrations of >4 μg/L lagging the onset of upwelling by ∼1 week. The associated (exponential) growth rate can be estimated at 0.4 d−1. Another week later we found a distinct sub‐surface chlorophyll‐a maximum at a depth of 50 m centred along the upwelling front. Reasons for the formation of this maximum are not fully understood.