Sunday, April 16, 2023

El-Nino...Will it or will it not affect Our Summer Monsoon ?...

Neutral Conditions through the Northern Hemisphere spring (April/May), followed by a 62% chance of El Niño developing during May-July 2023. 

Models remain highly biased with El-Nino 

In the year 1997, very strong El-Nino prevailed,. 

The behavior of the 1997 monsoon is related to its evolution during June and July, with westward migration of cloudbands from West Pacific that increased convection (Depressions) over Bay of Bengal.

 A similar behavior has also been noticed during the 1983 monsoon, with precursors indicating a possible poor monsoon but subsequent events changed the course of the monsoon.

"Based on El-Nino considerations alone, it has been feared, in some quarters, that 1997 might become a year of extreme deficit summer monsoon rainfall. However, the actual rainfall over India during June – September 1997 was 2 % above normal. India Meteorological Department had predicted "normal" rainfall (+-10% of the rainfall)."

A positive IOD saved that year from a poor Monsoon.  

2023 year also positive IOD will evolve during monsoon months. 

Models are not considering its impact, they are heavily skewed with ENSO conditions. 

So,Vagaries still will maintain nothing can be said with certainty how the monsoon will unfold,

 However in recent decades North India rain has strong correlation with ENSO conditions. But again, recent decades stats show there is almost no correlation of Central India rain with ENSO conditions.

 Intensity of El Nino in June/July/August also uncertain...that can play a big role in forcing the atmosphere to respond to ocean conditions

Important  point to be considered: This year first three months have been very "volatile", in extremes, meteorologically speaking.. So model based predictions have to be very conservatively analysed.

Note:  El-Nino does not guarantee entire India will see below normal rain  

  1. In the past decade, the El Niño occurred in 2002, 2004, 2006, and 2009
  2. But 2002-03 was the only year that India showed negative agri sector growth with average rainfall dropping 20 per cent below normal.

We need to be watchful and alert... not get to hasty conclusions and panic.

Author's Note with contributions from Vag. Dr. Vinnet and Vag. Shreyas.

4 comments:

sridu said...

Hi Rajesh, if its a El_NIno year what are the chances of increased cyclone formation over arabian sea and mumbai in particluar.. el-nino Modoki for instance ..

Rajesh said...

Sridu...Please read this article written earlier by me
http://devconsultancygroup.blogspot.com/2012/07/indian-monsoon-whats-brewing-in-pacific.htm

Rajesh said...

on Author's page in blog

sridu said...

Read it, Wow .. that was quite detailed... thanks....

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