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🌊 Indian Ocean Dipole (IOD) – UPSC Notes

IOD is an ocean-atmosphere phenomenon in the Indian Ocean. It is similar to El Niño but happens in the Indian Ocean, not the Pacific.
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🌊 Indian Ocean Dipole (IOD) – Explained Simply

🔹 What is IOD?

  • IOD is an ocean-atmosphere phenomenon in the Indian Ocean.

  • It is similar to El Niño but happens in the Indian Ocean, not the Pacific.

  • It refers to the difference in sea surface temperature (SST) between:

    • Western Indian Ocean (near Africa)

    • Eastern Indian Ocean (near Indonesia)

Indian Ocean Dipole

🔁 Types of IOD:

✅ 1. Positive IOD

  • Western Indian Ocean becomes warmer.

  • Eastern Indian Ocean becomes cooler.

  • Effect:

    • More rainfall in East Africa and India ☔

    • Drought in Indonesia and Australia 🌵

    • Good Indian monsoon

❌ 2. Negative IOD

  • Eastern Indian Ocean becomes warmer.

  • Western Indian Ocean becomes cooler.

  • Effect:

    • Less rainfall in India (weak monsoon) ☀️

    • More rainfall in Indonesia and Australia

🔄 3. Neutral IOD

  • Sea temperatures are nearly equal; no strong effect on weather.

🌀 IOD vs El Niño (Key Difference):

Feature IOD El Niño
Ocean Indian Ocean Pacific Ocean
Main Region Africa ↔ Indonesia South America ↔ Australia
Positive Phase Helps Indian Monsoon Weakens Indian Monsoon
Negative Phase Weak Monsoon May strengthen La Niña effects

🔍 Why IOD is Important for India (UPSC focus):

  • A positive IOD can neutralize the bad effect of El Niño on Indian monsoon.

  • IMD tracks IOD using satellite and sea data.

  • IOD impacts:

    • 🌾 Agriculture

    • 🌧️ Monsoon predictions

    • 🌀 Cyclone formation

🌐 Bonus:

  • IOD is part of the Indian Ocean climate system.

  • It can influence global weather patterns too.


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