Remotely-sensed estimation of alkalinity in coastal waters around Australia

Chair: Thomas Trull

Kimberlee Baldry(1,2), Nick Hardman-Mountford(1,2), Jim Greenwood(2), Bronte Tilbrook(3)

1 University of Western Australia, Crawley, WA, Australia
2 CSIRO Oceans & Atmosphere, Floreat, WA 6913, Australia
3 CSIRO Oceans & Atmosphere, Hobart, TAS 7001, Australia

Background
The Australian coastline is over 36,000kn long and comprises diverse and unique marine life. Notably, it is home to iconic reef systems hosting many marine organisms with carbonate-based skeletons which may be sensitive to changes in pH and carbonate saturation states.

Methods
We have analysed time series measurements of physical and biogeochemical variables obtained from the IMOS national reference station network around Australia to assess the accuracy of prediction for total alkalinity in Australian coastal waters, comparing local, regional and global approaches. We then reconstruct alkalinity using data derived from remote sensing satellites.

Findings/ Conclusions
We find that regional algorithms applied to remote sensing data provide a cost-effective means of extending alkalinity estimates from point time series around the vast Australian coastline. Such approaches will assist with monitoring potential changes in seawater alkalinity due to predicted changes in rainfall patterns around Australia, hence with monitoring the progress of ocean acidification in these valuable ecosystems.