Full Fledged El Nino Established End Of October 2023 – A Month After The Completion Of Southwest Monsoon In India

ભારતીય દક્ષિણ પશ્ચિમ ચોમાસુ પૂર્ણ થયા પછી એક મહિને વિધિવત એલ નિનો પ્રસ્થાપિત થયો

Enso Status on 4th November 2023

The first four El Nino thresh holds being AMJ 2023 ONI at +0.5ºC, MJJ 2023 ONI at +0.8ºC, JJA 2023 ONI at +1.1ºC and JAS 2023 ONI at +1.3ºC. Now the Fifth El Nino thresh hold has been achieved with ASO 2023 ONI at +1.5ºC, thereby completing five consecutive ONI >= +0.5ºC, fulfilling the criteria for a Full Fledged El Nino.

Ashok Patel’s Analysis & Commentary :

It had been mentioned here during the start of Southwest Monsoon in India that the  earliest a Full Fledged El Nino can be established would be at the end of October 2023. With the fifth El Nino thresh hold of ASO 2023 at +1.5ºC a Full Fledged El Nino has been established a month after the completion of Indian Southwest Monsoon season which ended at the end of September 2023. The other development is that SOI that was -13.0 level is currently -7.0 level end of October.

Indian Monsoon & Enso relationship for India:

Based on earlier more than 100 years weather Data for Indian Summer Monsoon, The Average Rainfall in an El Nino years is 94% of LPA while in La Nina Years it has been 106 % of LPA for the whole country. Monsoon Rainfall over India had been +94.4% of LPA at the end of 30th September 2023. El Nino or La Nina may affect the Monsoon differently for different Regions of India and warrants research for concrete co-relations for each region of India if any. Performance of Southwest Monsoon 2023 over the entire Country was much better than expected.

અશોક પટેલ નું તારણ અને વિશ્લેષણ :

ચોમાસા ની શરૂવાત માં જણાવેલ કે વિધિવત એલ નિનો ભારતીય દક્ષિણ પશ્ચિમ ચોમાસા દરમિયાન નહિ થાય તેમજ વહેલા માં વહેલું ઓક્ટોબર આખર માં થઇ શકે. તે ધારણા મુજબ, પાંચમું એલ નિનો ONI થ્રેશ હોલ્ડ ASO  +1.5ºC આવતા વિધિવત એલ નિનો શરુ થયો કહેવાય તે દક્ષિણ પશ્ચિમ ચોમાસુ પૂરું થયા બાદ એક મહિના પછી થયો. El Nino સાથે સંકળાયેલ પરિબળ SOI છે. SOI જે ઓક્ટોબર શરૂવાત માં -13.0 લેવલ માં હતો તે હવે -7.0 લેવલ પર છે. 

આગળ ના 100 વર્ષ થી વધુ ની શરેરાશ પ્રમાણે એલ નિનો વર્ષ માં ભારતીય ચોમાસુ 94% રહેલ છે, જયારે લા નિના વર્ષ માં ચોમાસુ 106% રહેલ છે. ભારતીય ચોમાસા માટે વિવિદ્ધ પરિબળો પૈકી નું એલ નિનો/લા નિના ફક્ત એક પરિબળ છે. ભારતીય દક્ષિણ પશ્ચિમ ચોમાસુ નબળું રહેવાની ધારણા હતી જે 94.4% રહ્યું જે નોર્મલ ગણાય. ભારત ના અલગ અલગ વિસ્તારો ના ચોમાસા પર એલ નિનો/લા નિના ની અસર એક સરખી નથી થતી, જે હાલ રિસર્ચ નો ઠોસ વિષય છે.

How ONI is determined:

The ONI is based on SST departures from average in the Niño 3.4 region, and is a principal measure for monitoring, assessing, and predicting ENSO. Defined as the three-month running-mean SST departures in the Niño 3.4 region. Departures are based on a set of further improved homogeneous historical SST analyses (Extended Reconstructed SST – ERSST.v5).

NOAA Operational Definitions for El Niño and La Niña, El Niño: characterized by a positive ONI greater than or equal to +0.5ºC. La Niña: characterized by a negative ONI less than or equal to -0.5ºC. By historical standards, to be classified as a full-fledged El Niño or La Niña episode, these thresholds must be exceeded for a period of at least 5 consecutive overlapping 3-month seasons.

CPC considers El Niño or La Niña conditions to occur when the monthly Niño3.4 OISST departures meet or exceed +/- 0.5ºC along with consistent atmospheric features. These anomalies must also be forecast to persist for 3 consecutive months.

The Climate Prediction Center (CPC) is a United States Federal Agency that is one of the NECP, which are a part of the NOAA

Latest Oceanic Nino Index Graph Shows
El Nino Has Been Established End Of October 2023

The Table below shows the monthly SST of Nino3.4 Region and the Climate adjusted normal SST and SST anomaly from July 2021. Climate Base 1991-2020. ERSST.v5

Period    Nino3.4 ClimAdjust
YR   MON  Temp.ºC Temp.ºC ANOM ºC


2021   7   26.90   27.29   -0.39
2021   8   26.32   26.86   -0.53
2021   9   26.16   26.72   -0.55
2021  10   25.78   26.72   -0.94
2021  11   25.76   26.70   -0.94
2021  12   25.54   26.60   -1.06
2022   1   25.61   26.55   -0.95
2022   2   25.88   26.76   -0.89
2022   3   26.33   27.29   -0.97
2022   4   26.72   27.83   -1.11
2022   5   26.83   27.94   -1.11
2022   6   26.98   27.73   -0.75
2022   7   26.60   27.29   -0.70
2022   8   25.88   26.86   -0.97
2022   9   25.65   26.72   -1.07
2022  10   25.73   26.72   -0.99
2022  11   25.80   26.70   -0.90
2022  12   25.75   26.60   -0.86
2023   1   25.84   26.55   -0.71
2023   2   26.30   26.76   -0.46
2023   3   27.19   27.29   -0.11
2023   4   27.96   27.83    0.14
2023   5   28.40   27.94    0.46
2023   6   28.57   27.73    0.84
2023   7   28.31   27.29    1.02
2023   8   28.21   26.86    1.35
2023   9   28.32   26.72    1.60
2023  10   28.38   26.72    1.66

Indications and analysis of various International Weather/Climate agencies monitoring ENSO conditions is depicted hereunder:

Summary by: Climate Prediction Center / NCEP  Dated 30th October 2023

ENSO Alert System Status: El Niño Advisory
El Niño conditions are observed.*
Equatorial sea surface temperatures (SSTs) are above average across the central and eastern Pacific Ocean.
The tropical Pacific atmospheric anomalies are consistent with El Niño.
El Niño is anticipated to continue through the Northern Hemisphere spring
(with an 80% chance during March-May 2024).* *

Note: These statements are updated once a month (2nd Thursday of each month) in association with the ENSO Diagnostics Discussion, which can be found by clicking here.

Southern Oscillation Index

As per BOM, Australia

The 30-day Southern Oscillation Index (SOI) for the period ending 31 October 2023 was −6.8, which was -13.0 around the first week of October.
Sustained negative values of the SOI below −7 typically indicate El Niño while sustained positive values above +7 typically indicate La Niña. Values between +7 and −7 generally indicate neutral conditions.

As per BOM – Australia 24 October 2023