Articles | Volume 13, issue 6
Biogeosciences, 13, 1967–1975, 2016
Biogeosciences, 13, 1967–1975, 2016

Research article 31 Mar 2016

Research article | 31 Mar 2016

Physical and biogeochemical spatial scales of variability in the East Australian Current separation from shelf glider measurements

Amandine Schaeffer1, Moninya Roughan1,3, Emlyn M. Jones2, and Dana White1 Amandine Schaeffer et al.
  • 1Coastal and Regional Oceanography Lab, School of Mathematics and Statistics, University of New South Wales, Sydney NSW, Australia
  • 2CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia
  • 3Sydney Institute of Marine Science, Mosman, NSW 2088, Australia

Abstract. In contrast to physical processes, biogeochemical processes are inherently patchy in the ocean, which affects both the observational sampling strategy and the representativeness of sparse measurements in data assimilating models. In situ observations from multiple glider deployments are analysed to characterize spatial scales of variability in both physical and biogeochemical properties, using an empirical statistical model. We find that decorrelation ranges are strongly dependent on the balance between local dynamics and mesoscale forcing. The shortest horizontal (5–10 km) and vertical (45 m) decorrelation ranges are for chlorophyll a fluorescence, whereas those variables that are a function of regional ocean and atmosphere dynamics (temperature and dissolved oxygen) result in anisotropic patterns with longer ranges along (28–37 km) than across the shelf (8–19 km). Variables affected by coastal processes (salinity and coloured dissolved organic matter) have an isotropic range similar to the baroclinic Rossby radius (10–15 km).

Short summary
The water properties of the coastal ocean such as temperature, salt, oxygen, or chlorophyll content vary spatially, and estimates need to be made regarding the scales of variability. Here, we use statistical techniques to determine the spatial variability of ocean properties from high-resolution measurements by gliders. We show that biological activity is patchy compared to the distribution of physical characteristics, and that the size and shape of this is determined by coastal ocean processes.
Final-revised paper