North West Australia Shelf

Quantifying vertical and lateral ocean transport due to submesoscale fronts and eddies

This project aims to quantify the intensity and location of submesoscale ocean currents (<50 km) with unprecedented spatial and temporal resolution on the biologically and economically significant Australian North West Shelf. Ocean processes at these scales dominate the lateral and vertical transport of ocean- borne material, including heat, larvae and pollutants, yet are poorly understood. The proposed cruise offers a once- off opportunity to collect simultaneous in-situ data during the unique rapid-sampling orbit of the pioneering high-resolution SWOT altimetry mission. Our key objectives are:

  1. Develop techniques for separating internal waves and eddies from SWOT 2D snapshots of sea surface height. The Australian Northwest Shelf is distinct from other CalVal regions due to the strength of the barotropic and baroclinic tide, making it a prime location to test these methods.
  2. Develop and test novel techniques to derive, with uncertainty, oceanic submesoscale currents (1-10 km) from remotely-sensed sea surface height (SSH) and/or sea surface temperature (SST) observations.

A novel spatial array of moorings will support the detailed ship-based observations, together providing critical data for development and testing of new algorithms for estimating ocean surface currents at unprecedented fine scales. This new knowledge will enable characterisation of submesoscale dynamics across broader spatial and time scales, elucidate relationships between mesoscale / submesoscale processes and vertical mixing, and establish physical understanding and data required for parameterisations. 

Expected outcomes include a paradigm shift in quantification of fine-scale ocean dynamics with global relevance. SWOT novel high-resolution ocean current information is directly applicable for search and rescue, offshore oil and gas operations, defence, ship routing, pollution response and ecosystem assessments in Australian waters. Our observations will advance regional- and global-scale ocean model predictions by improving our understanding of important subgridscale processes. The project will therefore bring economic, human safety and environmental benefits to Australia, while providing research training that will build Australian capacity in utilising remotely sensed environmental data and more generally in the space technology sector.

Principal investigators: Nicole L. Jones (University of Western Australia); Matt Rayson (University of Western Australia); Shane Keating (University of New South Wales); Jessica Benthuysen (Australian Institute of Marine Science); Jen-Ping Peng (University of Western Australia); Callum Shakespeare (Australian National University); Aurélien Ponte (Ifremer); Greg Ivey (University of Western Australia); Madi Rosevear (University of Western Australia).

Contact point for the study site: Nicole L Jones,

Instantaneous sea surface temperature (SST) from the Himawari-8 satellite in April 2021 with SWOT fast-sampling swaths (khaki), and IMOS mooring (red diamond). (Inset) Study region showing submesoscale eddies and filaments at one instant in time as the sea surface temperature gradient (greyscale). The location of the moorings and ship-surveys are shown (described in legend). BPR= bottom lander pressure sensor.