With the El Nino phenomenon expected to impact the Indian monsoon this year, the development of a positive Indian Ocean Dipole (IOD) has become crucial. The IOD holds the potential to offset the impacts of El Nino to some extent, offering hope for a balanced monsoon season.
Understanding ENSO (El Nino and Southern Oscillation):
ENSO (El Nino Southern Oscillation) is a climate phenomenon with the power to influence global atmospheric circulation, thus impacting temperature and precipitation patterns worldwide. It alternates between El Nino and La Nina phases irregularly every two to seven years. El Nino refers to above-average sea surface temperatures in the central and eastern tropical Pacific Ocean, while La Nina represents a cooling of these waters.
The Role of El Nino in Indian Monsoon:
El Nino, characterized by warmer ocean surface temperatures, often leads to below-normal monsoon rainfall in India. This climatic anomaly disrupts the intricate weather patterns and can result in drought-like conditions in certain regions, affecting agriculture and water resources.
Introduction to Indian Ocean Dipole (IOD):
The Indian Ocean Dipole (IOD) is an atmosphere-ocean coupled phenomenon occurring in the Indian Ocean. It is defined by the temperature difference between the eastern (Bay of Bengal) and western (Arabian Sea) parts of the ocean. The IOD, along with El Nino and La Nina, influences the behavior of the Indian monsoon.
Historical Performance of the IOD:
Although there is no established correlation between Indian summer monsoon rainfall and the IOD, past studies have shown that positive IOD years witness above-normal rainfall over central India. Notably, in 1997, the IOD delivered commendably by counterbalancing the negative effects of El Nino, resulting in a relatively stable monsoon season.
Current Status of El Nino and IOD:
While El Nino has already established itself in the Pacific Ocean this year, the IOD is currently in a neutral phase. However, there is optimism regarding the development of a positive IOD event in the coming months. Various international climate models support this expectation, and the India Meteorological Department (IMD) has also predicted an 80% chance of a positive IOD occurrence.
The Significance of a Positive IOD:
A positive IOD holds the potential to alleviate the impacts of El Nino to some extent, providing relief to regions affected by below-average monsoon rainfall. Its ability to bring above-normal rainfall to central India during positive IOD years contributes to the overall stability of the Indian monsoon.