Indian Ocean Dipole & Effects on Monsoon

Indian Ocean Dipole upsc notes
IMD predicts normal monsoon
El Nino event possibility
Monsoon and El Nino
Seasonal wind reversal
Brings heavy rainfall
Affects 25 countries
Covers 18000 km east to west
Covers 6000 km south to north
El Nino
Climate pattern
Warmer-than-average sea temperatures
In central and eastern Pacific Ocean
Has global weather impacts
Factors Impacting Monsoon Rains
El Nino/La Nina
El Nino weakens monsoons
La Nina enhances monsoons
Dateline El Nino/Central Pacific El Nino
Negative impact on monsoon
2005 El Nino an exception
Atlantic Nino
East-west anomaly pattern
Influences the monsoon
Indian Ocean Dipole (IOD)
Positive IOD enhances monsoon
Negative IOD weakens monsoon
Sea Surface Temperatures
Warmer enhances monsoon
Cooler weakens monsoon
Atmospheric Pressure
Change affects circulation and rainfall
Land-Sea Temperature Contrast
Greater contrast influences monsoon strength
Himalayan Mountain Range
Influences winds and rainfall patterns
Shapes local wind patterns
Affects rainfall distribution
Tropical Cyclones
Influence monsoon rainfall
Global Climate Patterns
Madden-Julian Oscillation affects monsoon dynamics
Local Factors
Vegetation, soil moisture, land use
Indian Ocean Dipole (IOD)
Climate phenomenon
Sea surface temperature fluctuation
Atmospheric pressure fluctuation
Similar to El Nino-Southern Oscillation (ENSO)
Effects of IOD on Monsoon
Positive IOD
Enhances monsoon rainfall
1997: Offset El Nino, above-normal rainfall
Negative IOD
Weakens monsoon rainfall
2019: Contributed to deficient rainfall
Neutral IOD
Minimal impact on monsoon
Monsoon Forecast Conditions (ESSO & IMD)
North Atlantic and North Pacific SST gradient
Equatorial south Indian Ocean SST
East Asia Mean Sea Level pressure
Northwest Europe surface air temperature
Equatorial Pacific Ocean warm water volume
Limitations in Forecasting
IOD and Atlantic Nino
Forecasting models lack reliability
Specific role in monsoon patterns uncertain
El Nino
Challenges in predicting location and intensity

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