Understanding the physical, chemical and biological processes across the subtropical convergence during austral automn

• Main Author: George, Caren
• Other Authors: Ansorge, Isabelle Jane, Froneman, William
• Format: Master Thesis
• Language: English
• Published: University of Cape Town 2009
• Subjects: Oceanography; Austral; Indian; Southern Ocean
• Online Access: http://hdl.handle.net/11427/6475; https://open.uct.ac.za/bitstream/11427/6475/1/thesis_sci_2009_george_c.pdf

Includes abstract. Includes bibliographical references (leaves 49-58). A research survey was conducted, consisting of six transects between 38°- 46°S and 38 - 41°45'E, during the austral autumn of 2007. The aim of the survey was to investigate the physical, chemical and biological dynamics of the Subtropical Convergence (STC), in the SW Indian sector of the Southern Ocean. Satellite data was obtained and in-situ data were collected. Mixed layer depth (MLD), geostrophic velocities, density and Brunt Vaisala frequencies were calculated. The STC meandered across the survey area between 41 ° - 42°15'S. The total integrated Chl-a ranged from 12.8 to 40.1 mg Chl-a/m2. The most significant correlation between biological and physical data was that of Chl-a and MLD (r=-0.374, n=45, p=0.013) over the entire survey region. Phosphate and nitrate (r=0.8779, n=45, p=0.001) measured over the survey region were strongly correlated, as expected. The surface currents showed cyclonic motion between 38° - 39°E and 38 - 42°S, with the exception of an eddy-like feature between 39.5°and 40.5"S and generally anti-cyclonic motion to the east of 39°E.