Australia: The Land Where Time Began

A biography of the Australian continent 

East Australian Current and its eddies – Recent Freshening

The East Australian Current (EAC) has a mean flow that is relatively weak and an eddy field that is energetic which dominates the circulation. There have been detailed studies on the mean flow but there has not been much attention paid to changes in the eddy field. In this paper Rykova & Oke report the results of their analysis of Argo temperature and salinity profiles for 2005-2012 in order to construct a picture of the time-mean and time-varying properties of EAC eddies. Their results show that freshening is occurring at a rate of 0.017-0.025 practical salinity unit/year of the top 100 m of the eddies and their surrounding waters in the western Tasman Sea, though there has been no significant change of temperature. Fields from an ocean model that resolves eddies shows freshening with no trend in temperature, which is consistent with the observations. The results of the model also indicate that in the context of the variability over the last 20 years observed changes are significant and may be part of a multilayer, possibly decadal, cycle. Rykova & Oke attribute freshening of the region to increased precipitation off Eastern Australia.

Sources & Further reading

1. Rykova, T. and P. R. Oke (2015). "Recent freshening of the East Australian Current and its eddies." Geophysical Research Letters 42(21): 2015GL066050.