Research Papers

Mesoscale features and phytoplankton biomass at the GoodHope line in the Southern Ocean during austral summer

Published in: African Journal of Marine Science
Volume 34, issue 4, 2012, pages: 511–524
DOI: 10.2989/1814232X.2012.749811
Author(s): S SwartSouthern Ocean Carbon and Climate Observatory, South Africa, SJ ThomallaSouthern Ocean Carbon and Climate Observatory, South Africa, PMS MonteiroSouthern Ocean Carbon and Climate Observatory, South Africa, IJ AnsorgeDepartment of Oceanography, Marine Research Institute, South Africa

Abstract

Two sets of high-resolution subsurface hydrographic and underway surface chlorophyll a (Chl a) measurements are used, in conjunction with satellite remotely sensed data, to investigate the upper layer oceanography (mesoscale features and mixed layer depth variability) and phytoplankton biomass at the GoodHope line south of Africa, during the 2010–2011 austral summer. The link between physical parameters of the upper ocean, specifically frontal activity, to the spatially varying in situ and satellite measurements of Chl a concentrations is investigated. The observations provide evidence to show that the fronts act to both enhance phytoplankton biomass as well as to delimit regions of similar chlorophyll concentrations, although the front–chlorophyll relationships become obscure towards the end of the growing season due to bloom advection and ‘patchy’ Chl a behaviour. Satellite ocean colour measurements are compared to in situ chlorophyll measurements to assess the disparity between the two sampling techniques. The scientific value of the time-series of oceanographic observations collected at the GoodHope line between 2004 to present is being realised. Continued efforts in this programme are essential to better understand both the physical and biogeochemical dynamics of the upper ocean in the Atlantic sector of the Southern Ocean.

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