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What is it
El Niño is the warm phase of the El Niño Southern Oscillation (ENSO), a climate event that happens when warm water in the Pacific Ocean interacts with the atmosphere, causing various weather events around the world, from droughts to floods.
An El Niño arrives on a cycle of about every three to seven years. There are several clues that one is brewing around the corner this year, all of which meteorologists have been keeping a keen eye on for over a year.
Origins
El Niño meaning, The Little Boy, or Christ Child was originally recognized by fishermen off the coast of South America in the 1600s, with the appearance of unusually warm water in the Pacific Ocean. The name was chosen based on the time of year (around December) during which these warm waters events tended to occur.
Effect
El Niño affects the weather in large parts of the world. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.
The effects depend strongly on the location and the season. The strongest effects on precipitation are in South-East Asia and the western Pacifc Ocean, especially in the dry season (August-November). There are temperature effects throughout most of the tropics. The number of tropical cyclones also depends on El Niño in most basins. In boreal winter the effects are most wide-spread: from southern Africa to eastern Russia and most of the Americas.
Video on El Niño by MET Office Hadley Centre
EFFECT ON INDIA
India Meteorological Department announced last week that even as the possibility of below-par rainfall grew, both IMD and US forecasters have predicted a greatly increased chance of El Niño conditions persisting through the summer.
The Indian monsoon -- which besides India, also affects other regions of south and southeast Asia and Australia -- is the most monetarily important because of its profound influence on the economy of India and neighboring countries.
It is directly linked to the ENSO phenomenon. In summer months, temperatures over much of India rise to as high as 110 degrees Fahrenheit while the Indian Ocean is much cooler. Consequently, the warm air over the land rises and cooler moisture-bearing air blows in from the sea, bringing heavy rains to the region.
ENSO-induced warm zones in the Pacific cause the warm air over them to rise and initiate circulation cells. Such cells along northern Australia, Indonesia and the eastern edge of the Indian Ocean could have their downdraft sides over a nascent monsoon circulation cell in the Indian Ocean, which would disrupt its formation, causing poor monsoon rains over the subcontinent.
This Indian monsoon model thus implies that El Niño years should coincide with deficient monsoon rains.
The MET department has already blamed the El Niño phenomenon for below normal rainfall this year."El Niño has affected rainfall bringing it below normal eight times in past 14 years. The impact of El Niño has been factored in this year's forecast," said IMD Director General Laxman Rathore.
Adam Scaife, professor at the Met Office Hadley Centre for Climate Change, tells online weather portal Geographical, that with the current prediction, the Indian monsoon, tropical West Africa, the maritime continent [Indonesia], and Australian impacts - all of those regions are at increased risk of drought.
For particularly India's case he says, “In the summer to autumn – when the Indian monsoon is active – it is likely to suppress the monsoon convection and kill off the rainfall. This is only around perhaps ten per cent or so of the total rainfall in the monsoon season, but that ten per cent is a big change. It affects agriculture, it causes breaks in the monsoon when there’s no rainfall at all, and if that lasts too long then obviously crops wilt and die. So there are all sorts of impacts on agriculture.”
In another view, according to Balaji Rajagopalan, Assistant Professor at the College Of Engineering & Applied Science, University of Colorado, more than 100 years scientists have connected the variability of the summer monsoon rains in India to El Niño. But events in the last 25 years seem to have reduced forecasters’ ability to predict the monsoon to a mere roll of the dice.
He further says the effect turns out to be more adverse for India as the country lacks large reservoirs that can moderate a drought’s impact on food supplies.
What records say
Analysis by the India Meteorological Department shows that, of the 18 El Niño years between 1880 and 2006, twelve coincided with deficient or below-normal rainfall in India. This means that, for a third of the time, there was no correlation, and that has resulted in some spectacularly wrong forecasts for the monsoon.
More recent research however aimed at finding a more robust correlation indicates that not all El Niño's cause drought, and only warming in the central Pacific correlates with drought in India while warming in the eastern Pacific means a normal monsoon.
