The Indian Ocean Dipoles

I have heard mention of the Indian Ocean Dipole [IOD] quite a few times recently in stories concerning the widespread bushfires in Australia. I decided to take a look at the latest SST in the Indian Ocean and see if I could find out a little more about what the IOD is. There are in fact two dipoles for the Indian Ocean the Indian Ocean Dipole [IOD] and the Subtropical Indian Ocean Dipole [SIOD]. A dipole in this instance is just a comparison in the SST anomalies between two areas expressed as an index. The two dipoles of the IOD, often referred to as the Indian El Niño, with the western one off the east coast of Africa with the eastern one close to the island of Sumatra. The chart below is of the latest SST anomalies across the Indian Ocean with the area of the two dipoles marked on it in black, the dipoles of the SIOD in the southern Indian Ocean are marked out with white squares. For a more informed look at why the IOD is one of the key drivers for the climate of Australia take a look at this really informative article about it on the BOM site (no pun intended!).

Courtesy of NCOF

As you can see from the colours in the two black rectangles of the SST chart, the anomalies in two dipole areas are quite similar now in mid January, suggesting that the IOD has returned to a more neutral phase. You can see this in the graph of the IOD which has fallen dramatically in the second half of 2019. I have also included a long range forecast which suggests the IOD will remain neutral till at least June.

Courtesy of the Australian BOM

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