Recent freshening of the East Australian Current and its eddies

• Published in: Geophysical research letters Vol. 42; no. 21; pp. 9369 - 9378
• Main Authors: Rykova, Tatiana, Oke, Peter R.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 16.11.2015; John Wiley & Sons, Inc
• Subjects: Argo; Atmospheric precipitations; Australia; Brackish; Circulation; East Australian Current; Eddies; Eddy currents; Fields; Floats; freshening; Geophysics; interannual variability; Marine; mesoscale eddies; Meteorology; Ocean circulation; Ocean currents; Ocean models; Precipitation; Profiles; Properties; Salinity; Salinity effects; Salinity profiles; Temperature; Temperature effects; Trends; Variability; Tasman Sea; Australia; ISEW, Coral Sea, East Australian Current; PSE, Tasman Sea
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2015GL066050

The East Australian Current (EAC) has a relatively weak mean flow and an energetic eddy field that dominates the circulation. The properties of the mean flow have been studied in detail, but the changes in the eddy field have received little attention. We analyze Argo temperature and salinity profiles for 2005–2012 to construct a picture of the time‐mean and time‐varying properties of EAC eddies. We find that eddies and the surrounding waters of the western Tasman Sea are freshening at a rate of 0.017–0.025 practical salinity unit/yr over the top 100 m, with no significant temperature change. Consistent with the observations, fields from an eddy‐resolving ocean model show freshening, with no temperature trend. Moreover, the model results indicate that observed changes are significant in the context of the variability over the last 20 years and may be part of a multiyear (perhaps decadal) cycle. We attribute the freshening of the region to increased precipitation off Eastern Australia. Key Points Argo float data show that the EAC and its eddies have freshened over 2005–2012 There is no warming of the EAC and eddies in neither Argo, nor XBT, nor model fields The freshening is caused by increased precipitation off Eastern Australia