Indian Ocean affects Australian drought

The Climate Change Research Centre at the University of New South Wales has been doing some interesting research. They have found a correlation between three of Australia's largest droughts (1895-1902, 1937-1945, and the present one, since 1995) and oceanic conditions - in the Indian ocean!

Say what? Shouldn't that be the Pacific and El Nino?

Apparently not.

In a paper to be published in Geophysical Research Letters, the team have linked the last three major droughts in Australia with the Indian Ocean Dipole (IOD).

Basically, the dipole consists of a cooler body of water in the central Indian Ocean, and a warmer body of water to the north east. This is a negative IOD (-IOD).

Under these conditions, warm, moist air forms along Indonesia, and is channeled from there, across western Australia and then across southern Australia. This happens because the warm moist air formed over Indonesia is influenced by the weather patterns that run west to east across southern Australia, and the moist air is dragged diagonally across the continent.

This is good, because it brings rain to western and southern Australia

However, when things are reversed, with a warm body of water in the central Indian Ocean, and a cool body of water to the north east (a positive IOD), warm, moist air does not form.

This is bad because it results in drought to western and southern Australia.

So -IOD good, +IOD bad.

The team has found that throughout the period 1995 to present, no -IODs have formed, and similarly -IODs were rare in previous times of extended drought.

What about El Nino? Well, we are actually in an El Nina at the moment, and there have been several in the last 12 years.

So it looks like there is a better fit with IOD than with El Nino/El Nina.