There is a looming fear that El Niño might disrupt India’s monsoon rains. In such a scenario, the Indian Ocean Dipole (IOD) emerges as a major ray of hope for our farmers. Here is a detailed look at this phenomenon.
The Indian agricultural sector is entirely dependent on the monsoon (Southwest) rains. In recent years, due to global climate change, the ‘El Niño’ phenomenon frequently weakens the monsoon, raising fears of drought. In these times, the Indian Ocean Dipole (IOD) acts as a saviour for India. It is highly essential for our farmers to understand the IOD to plan their cropping patterns and irrigation effectively.
What is the Indian Ocean Dipole (IOD)?
Simply put, the difference in sea surface temperatures between the eastern part of the Indian Ocean (near Indonesia) and the western part (near the east coast of Africa) is called the ‘Indian Ocean Dipole’. It severely impacts ocean winds and rain-bearing monsoon currents. It consists of three phases:
Positive IOD (The Farmer’s Friend): In this state, the waters of the western Indian Ocean near Africa become warmer than normal, while the eastern part near Indonesia cools down. Negative IOD (Harmful to Rain): This is the exact opposite of the positive phase. Here, the waters near Indonesia become warmer, and the waters near Africa cool down.
Neutral IOD: The ocean temperatures remain around normal levels.
The Dynamic Between El Niño and Positive IOD
When ‘El Niño’ is active, there is a more than 60% chance of a deficit monsoon and subsequent drought in India. However, if a Positive IOD develops in the Indian Ocean during the same year, it counteracts the ill effects of El Niño.
Increased evaporation occurs over the Arabian Sea from the warmer western Indian Ocean, creating strong rain clouds. The monsoon winds then push these clouds toward the Indian landmass. As a result, even during an El Niño year, India—especially Southern and Central India—receives good or normal rainfall.
What are the Benefits for Farmers?
When a Positive IOD is active, farmers can expect the following positive changes:
Adequate Monsoon Rains: Timely rains suitable for sowing become available.
Groundwater Recharge: Good rainfall between July and September helps increase the water table in lakes, ponds, and borewells. A Boon for Rabi Crops: A Positive IOD sometimes extends the monsoon rains into October. This leaves excellent residual moisture in the soil for sowing winter (Rabi) crops.
Precautions and Tips for Farmers
When the meteorological department forecasts a Positive IOD, farmers can confidently plan their agricultural operations without panicking. Even if the rainfall is slightly delayed at the beginning of the monsoon due to El Niño, the IOD influence brings heavy rains in July-August.
Sow Wisely: Sow your seeds only after the soil has gained full moisture. Water Management: Just because good rain is expected, do not over-irrigate. Set up proper drainage systems in fields and orchards to prevent crops from rotting due to excess water.
Water Harvesting: Build recharge pits (soak pits) in farms to trap rainwater, securing groundwater for the upcoming summer. While nature poses a challenge through El Niño in the Pacific Ocean, it simultaneously provides a solution through the IOD in the Indian Ocean. By keeping an eye on weather forecasts and farming scientifically using rays of hope like the IOD, farmers can achieve an excellent yield
