Meteorologists are likely to review the threat to the Indian monsoon from a possible El Nino. Scientists from the India Meteorological Department, Indian Institute of Tropical Meteorology and the Ministry of Earth Sciences are expected to meet in Pune later this week to analyse a range of forecasts from international climate models – and their own –that suggest waters are likely to warm and change wind patterns enough to El Nino-like conditions.
El Nino refers to an anomalous heating up of the waters in the central-eastern regions of the equatorial Pacific and implies a consistent, average rise in temperature of 0.5 degree Celsius above normal. Historically that translates to the monsoon drying up over India six out of 10 years.
In the normal course of events, the Pacific waters ought to have been in the converse cool, La Nina mode and only begin a warming trend late after India’s summer monsoon period of June-September.
However these trends are expected to begin around March and – the part that’s still contentious – have an El Nino during the latter half of the monsoon.
Meteorologists however say it’s too early to be sure of an El Nino and its impact on the monsoon.
For one, predictions made from a climate model before March could dramatically differ from that in April or later because of the way oceans and atmosphere influence each other, a phenomena that meteorologist call the Spring Barrier effect. Secondly, according to K.J. Ramesh, Director General of IMD, an El Nino by itself wasn’t enough to disrupt a monsoon.
“We have to study how it influences the sea around India and there could be local factors that may be stronger,” he told The Hindu. However, one significant influencer, the Indian Ocean Dipole (IOD), doesn’t bode well for India. According to a report by the IMD in mid January: “…positive IOD conditions weaken in MAM (March, April, May) and turn to negative IOD conditions from AMJ (April, May, June) onwards.” A positive IOD is traditionally known to bolster monsoon rains in India.
