An Introduction to the Indian Ocean Dipole Zhuomin Chenzchen@marine.rutgers.edu

What is IOD?First described by Dr. Saji et al. in 1999 Second mode of EOF, explains about 12% of the total variation of anomalous Indian Ocean sea-surface temperatures Dipole Mode Index (DMI)

Evolution of a Dipole Mode EventAn IOD event usually starts around May or Jun, intensifies in the following months and peaks between Aug and Oct and then rapidly decays.

Positive & Negative Phases of IOD

Positive: cooler in the tropical eastern Indian Ocean and warmer in the tropical western Indian OceanNegative: warmer in the tropical eastern Indian Ocean and cooler in the tropical western Indian Ocean

IOD Influence on Surrounding ClimateA positive phase of the IOD tends to cause droughts in East Asia and Australia, and flooding in parts of the Indian subcontinent and East Africa.

Australian droughtsA 2009 study by Ummenhofer et al. at the University of New South Wales Climate Change Research Centre, has demonstrated a significant correlation between the IOD and drought in the southern half of Australia, in particular the south-east.

Floods in Kenya, Eastern Africa

Preconditioned major wildfires in southeast AustraliaCaused coral reef death across western SumatraExacerbated malaria outbreaks in East Africa A better understanding of the relationship between the Indian Ocean Dipole and extreme weather eventsHowever many problems still remain unsolved. have not reached an agreement on how IOD formed;have questions about the relationship between ENSO and IOD;and how they affect the climate together More Effort Counts!Summary

Thank you!