An Introduction to the Indian Ocean Dipole Zhuomin Chen zchen@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 Event An 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 Ocean Negative: warmer in the tropical eastern Indian Ocean and cooler in the tropical western Indian Ocean Positive IOD Phase Negative IOD Phase

IOD Influence on Surrounding Climate A 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 droughts A 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

However many problems still remain unsolved. Summary Preconditioned major wildfires in southeast Australia Caused coral reef death across western Sumatra Exacerbated malaria outbreaks in East Africa …… A better understanding of the relationship between the Indian Ocean Dipole and extreme weather events…… However 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!

Thank you!