Recent analyses reveal that the El Niño weather phenomenon, known for its cyclical nature, significantly impacts rainfall patterns across India. This complex system, characterized by the warming of surface waters in the eastern Pacific Ocean, weakens trade winds and alters various atmospheric conditions. Normally, El Niño has a strong suppressive effect on summer rainfall in India. New findings show a more shocking trend — the intensification of rainfall is most pronounced in the dampest parts of the country.
Further, researchers analyzed daily records of rainfall from the India Meteorological Department, spanning 1901-2020. Their goal is to determine the complex, changing connection between El Niño events and the Indian monsoon rainfall. Their results indicate that El Niño summers result in a statistically significant increase in extreme precipitation days. This holds particularly true for areas already accustomed to excessive precipitation.
Understanding El Niño’s Mechanism
El Niño interferes with the usual climate-related patterns across the globe—primarily through its effects on sea surface temperatures and atmospheric circulation. The phenomenon’s weakening of the trade winds has been sufficient to cause severe disruptions in upper-level weather patterns. In India, this results in an unusual pattern: while overall rainfall may decrease in some parts of the country, the wettest regions see an increase in daily rainfall.
The researchers calculated that extremely heavy downpours over 250 mm are 43% more likely in El Niño years. The latter is a pattern all too familiar in every monsoon-affected region across India. For the Central Monsoon Zone, this increase is even higher, jumping to 59%! More arid areas will face worsening drought conditions. At the same time, places that typically get a lot of rain are going to experience a significant intensification of precipitation.
Impact on Rainfall Distribution
The varied impacts of El Niño across India highlight the complicated behavior of this climate phenomenon. Dry conditions prevail across southeastern and northwestern India. In times of El Niño, these regions see less overall precipitation and are protected from more severe weather patterns. In climate vulnerable areas, such as the Western Ghats and northeastern states, El Niño summers enhance convective buoyancy. This dramatic increase significantly exacerbates the occurrence of extreme rainfall events throughout these undisturbed spaces.
The scientists applied advanced statistical methods to determine the occurrence, return period, and intensity of these one-in-a-hundred-year extreme rainfall events. To answer this question, they cross-referenced atmospheric data from 1979-2020 with historical rainfall records. This analysis showed that the connections between El Niño conditions and increased precipitation in humid areas are strong. These findings show a critical link. The more severe the El Niño conditions become, the greater the chance of extreme daily rainfall.
Implications for Weather Forecasting
The link between El Niño and Indian rainfall has far-reaching consequences for meteorological prediction and disaster preparedness. More accurate predictions of rainfall patterns informed by El Niño would be an important part of reducing the risk of flooding before it starts. By predicting intense rainfall events in advance, decision-makers can take proactive steps to safeguard lives and property in high-risk communities.