With indications of a milder El Niño and a positive Indian Ocean Dipole, rainfall during the summer monsoon this year is likely to be well-distributed across the country and yield India’s third consecutive good harvest of kharif crops, the Met office clarified as one of its forecast models still shows the probability of below-normal rains in June.
Based on initial conditions in February, the India Meteorological Department’s climate forecast system model showed below-normal rainfall for the country in June. However, the Met office said the parameters have changed significantly now.
“El Niño was warmer in February but it has become milder now, which will help the country get normal rainfall… The model forecast based on initial conditions of April is very different,” said KJ Ramesh, director general of IMD. “With positive IOD (Indian Ocean Dipole) over equatorial Indian Ocean during the monsoon season of 2019, it suggests a normal season with very good spatial rainfall distribution that should turn into a third consecutively good kharif season for the farming community of India.”
While the IMD predicted that this year’s monsoon rainfall would be “near normal,” the Australian Bureau of Meteorology retained its El Nino alert outlook, saying the chances of the weather phenomenon developing in the coming months is about 70%, which is almost three times the normal likelihood. However, the Bureau also said that if El Niño does develop, it is likely to be short-lived and weak.
El Niño, associated with the warming of the sea surface in the Pacific Ocean, has sometimes reduced the monsoon rainfall in India and even resulted in drought. The IOD refers to the oscillating sea surface temperatures in the Indian Ocean, with the western part becoming warmer and then colder than the eastern part. A weaker El Niño and the prospect of the IOD remaining positive during the monsoon months are likely to help India get better rains.
Although meteorologists are upbeat about normal rainfall as the El Niño weakens, research says its relationship with the Indian monsoon is complex.
“Most of the severe droughts over India are associated with El Niño,” M Rajivan, secretary of the Ministry of Earth Sciences, and DS Pai, head of Long Range Forecast at IMD, said in a research paper. “However, only less than half of El Niño events are associated with deficient rainfall over India.”
Their research shows that all severe droughts (with less than 20% of normal monsoon rainfall) in India occurred in association with El Niño events. However, there is no one-to-one relationship.
Observations over the 1880–2005 period indicate that the Indian summer monsoon rainfall was deficient only in 43% of El Niño events, while in other El Niño years, monsoon rainfall was either normal or above normal.
Another paper by Pai suggested that the monsoon rainfall has a cyclical nature. While rainfall during 1905-1945 was below normal, it was above normal during 1945-1986. The present epoch that started in 1986 is of below-normal rainfall. Data shows that during epochs of below-normal rainfall, the association between the monsoon and El Niño is strong.