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19.02.2016 01:08 Age: 2 yrs
Category: Home Slider, IMOS OceanColour, SA-IMOS

The Bonney Coast Upwelling: biological hotspot sampled by an IMOS glider

An IMOS Slocum glider is presently making the most detailed survey ever conducted of the bio-physical properties of a Bonney Coast upwelling event.


Glider track Bonney Coast 1-13 February, 2016

Chlorophyll-a image for Bonney Coast 9 Feb, 2016, showing the track of the glider as a blue line at bottom right

The dissolved oxygen data are perhaps the most exciting: percent saturation values exceeded 150 within the upwelled water on 3 February, confirming that the phytoplankton were very actively photo-synthesising, producing much more oxygen than was lost to the atmosphere. You can step through the mission seeing either 4 days or 12 days of the mission track at a time.

Excepting some spurious measurements affected by bio-fouling, values this high have not been seen in Australian waters by the glider fleet. The closest comparison was in upwelled waters inshore of the East Australian Current near Coffs Harbour in Dec 2010, but these may have been affected by bio-fouling. The present mission dissolved oxygen data are not suspicious, because the high readings occurred early in the mission.

The Bonney Coast is the 200km-long stretch of narrow continental shelf near Portland, Victoria, that is famous (especially, but not only, in marine scientist circles) for its periods of summer-time wind-driven upwelling. Upwelling events are routinely evident in satellite imagery but rarely sampled extensively at sea.

MODIS estimates of chlorophyll-a show that the present event is not an extraordinary one. The track of the glider can be seen in the image to the right as a blue line (bottom right of image). See also the chlorophyll-a images for 1 February and onwards, and/or sea surface temperature images.

 

Article sourced from IMOS OceanCurrent News.