El Nino: Will 2014 be a drought year for India?

 
By Vani Manocha
Last Updated: Saturday 04 July 2015

 

imageLatest updates by two international weather bureaus have given India some reason to dread monsoon forecasts which would begin next month. 

The Australian Bureau of Meteorology, on Thursday, said factors that lead to an El Nino were now increasingly visible. "The tropical Pacific Ocean subsurface has warmed substantially over the past few weeks, which was likely to result in a warming of the sea surface in the coming months," it said. US agency National Oceanic and Atmospheric Administration's Climate Prediction Center, which updated its forecast on Wednesday, said temperature anomalies associated with El Nino had strongly increased since the end of January and there was a 50 per cent chance of El Nino developing during the summer or autumn this year.  

El Nino, which refers to the Christ child, is an unusual warming of sea surface waters in eastern and central equatorial Pacific associated with changes in wind patterns that impact weather in many parts of the world. It generally has an adverse effect on the Indian monsoon. 

Last week, Crisil, a credit rating and market research company, said it might have to scale down the economic growth projection for 2014-15 to 5.2 per cent from six per cent in the event of El Nino-driven poor monsoon. According to a few media reports, D Sivanada Pai, lead monsoon forecaster at India Meteorological Department (IMD), has already warned that there is a good chance of El Nino forming this year. But whether it would impact the Indian monsoon or not would depend on its intensity and the timing of its onset. IMD would be making its first prediction on monsoon’s arrival by next month.

Why is El Nino so dreaded?

El Nino/La Nina-Southern Oscillation or ENSO is an ocean-atmospheric phenomenon that occurs in a cycle. La Nina, which is one part of the cycle, is signified by a decrease of 3-5°C in sea surface temperature across the Equatorial Pacific Ocean and it is favourable for monsoons in India. El Nino, which is La Nina’s counter-phenomenon, is often accompanied by drought in India and heavy rainfall in the Pacific coast of Latin America.

Over the years, research has shown there is an association between El Nino and deficient rainfall in India. However, all El Nino years are not deficient in rainfall. Pai, who is also director of long-range forecasting at IMD, says 1997 saw the strongest El Nino phenomenon in the last century, but the monsoon rainfall that year was 101 per cent of long-period average (average of 50 years), which means it was marginally more than 89 cm. The five major droughts of the past 20 years—1982, 1987, 2002, 2004 and 2009—were accompanied by El Nino. A research analysis between 1880 and 2004 by Krishna Kumar of Indian Institute of Tropical Meteorology (IITM) shows that in 13 instances of El Nino occurrence, India experienced normal monsoon rainfall, while in 10 instances rainfall was below normal.

The first prediction on monsoon arrival would be done after the South Asian Climate Outlook Forum scheduled for April 22- 23 in Pune. Based on the weather inputs, agriculture secretary Ashish Bahuguna on Friday asked states to brace for any eventuality.

 

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  • El Nino &La Nina factors were

    El Nino &La Nina factors were used in the long range southwest monsoon rainfall forecasts in India over more than 60 years but failed on many occasions -- this is only one component. Very rarely these long range forecasts predicted extremes -- beyond < 90% [2002, 2004 & 2009] and more than 110% [1994-98, 2003, 2007, 2010-2011] of the mean. The forecast lied between 90 and 110 [normal]. While my 60-year cycle presented above the average pattern since 1987 on majority of the years with 2 to 3 years below the 90% of the average, which will end by 2016 and below the average pattern starts from 2017 onwards -- on majority of the years they fall under below the average with 2 to 3 years above 110% of the average.

    However, the pattern is quite different in areas with southwest & northeast monsoon and in association with Bay of Bengal cyclonic activity. The below the average precipitation pattern already started here.

    Indian scientists are using El Nino and La Nina to ascertain the drought and crop production but they are random in nature.

    Dr. S. Jeevananda Reddy

    Posted by: Anonymous | 6 years ago | Reply