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Indian Ocean Dipole (IOD)

Indian Ocean Dipole describes the changing position of warm and cool waters in the east and west Indian Ocean.

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Read the transcript: Climatedogs - Indy

Click a Climatedog below to view animation:

Key things to know about IOD

Did you know... (click here to find out)
Indy was in positive phase (drier) for 2006, 2007 and 2008.....and we haven't had a good IOD negative since the 1990's (ie 1992, 1993 & 1996 were all IOD negative)
  • The IOD changes between positive, neutral and negative phases.
  • When warmer surface waters are closer to Australia (IOD negative), more moisture becomes available for rainfall.
  • This moisture can travel towards Victoria through stronger winds and large north-west cloud bands.
  • When moisture arrives in Victoria, and connects with cold fronts, higher rainfall can occur.
  • Positive and neutral IOD events have been linked with drought in Australia.

IOD positive

Positive IOD Diagram

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This occurs when the Indian Ocean is warmer in the west (near the coast of Kenya) than it is in the east (near Sumatra). This reduces tropical moisture availability for Victoria, and can make for a drier spring.

Read more about Australian rainfall patterns during positive Indian Ocean Dipole years.

IOD negative

Negative IOD Diagram

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When the Indian Ocean is warmer in the east than it is in the west we have an IOD negative event. This means that more moisture is available closer to Australia, and can be delivered to Victoria through northwest cloud bands. Typically IOD negative events have been associated with wetter seasons in Victoria.

Read more about Australian rainfall patterns during negative Indian Ocean Dipole years.

Where to go for more information

For more information about the IOD visit some of the pages below.

  • Read more about how the Indian Ocean impacts on Australian weather and climate.
  • More information about the Indy on the Bureau of Meteorology website.
  • Read a fact sheet from the South East Australian Climate Initiative about how the region's climate is changing, including research into how Indy influences our climate.