Category: ENSO

Second Seasonal El Nino Thresh Hold Reached – Full Fledged El Nino As Per NOAA Criteria Requires ONI >= +0.5ºC For A Continuous Period Of Three More Months

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Second Seasonal El Nino Thresh Hold Reached – Full Fledged El Nino As Per NOAA Criteria Requires ONI >= +0.5ºC For A Continuous Period Of Three More Months

El Nino થ્રેશ હોલ્ડ બીજા ચરણે પહોંચ્યું – હવે વિધિવત El Nino માટે NOAA ના નિયમો મુજબ સળંગ ત્રણ મહિના ONI >= +0.5ºC રહેવું જોઈએ

Enso Status on 4th August 2023

Second El Nino thresh hold has been achieved for MJJ 2023 with ONI at +0.8ºC, the first El Nino thresh hold being for AMJ 2023 with ONI at +0.5ºC. Earlier Enso Neutral conditions had prevailed in the earlier three 3-monthly seasons JFM ONI at -0.4ºC, FMA ONI at -0.1ºC and MAM 2023 ONI at +0.2ºC.

Ashok Patel’s Analysis & Commentary :

Second El Nino thresh hold has been achieved for MJJ 2023 with ONI at +0.8ºC, the first El Nino thresh hold being for AMJ 2023 with ONI at +0.5ºC. Earlier Enso Neutral conditions had prevailed in the earlier three 3-monthly seasons JFM ONI at -0.4ºC, FMA ONI at -0.1ºC and MAM 2023 ONI at +0.2ºC. NOAA criteria stipulates that a Full fledged El Nino requires five 3-monthly seasons with ONI => +0.5C, which can only be achieved earliest at the end of October 2023 since only two El Nino thresh holds have been achieved and three consecutive more thresh holds have to be achieved. Hence it can be concluded that a full fledged El Nino is not possible during the Indian Southwest Monsoon season which ends at the end of September 2023. The other development is that SOI is currently in the Neutral territory after having been in negative zone in May 2023. Pacific Ocean and atmosphere were not fully coupled, as occurs during El Niño events. However, SOI is now progressing towards the negative zone as required for an El Nino event.

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 +106% of LPA at the end of 30th September 2022. 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 is much better than expected. See the Graph for Rainfall performance over India till 3rd August 2023. Although the second El Nino thresh hold is at +0.8ºC the corresponding Rainfall for July 2023 has been a very much above normal. However, Kerala, Bihar & Jharkhand have a huge deficit of rainfall till date while All the States from Gujarat Rajasthan, Punjab, Haryana, Jammu & Kashmir, Himachal Pradesh, Ladakh & Telangana have received huge surplus rainfall.

અશોક પટેલ નું તારણ અને વિશ્લેષણ :

MJJ 2023 નું ONI +0.8ºC છે અને AMJ 2023 નું ONI +0.5ºC હોય એટલે કે El Nino બીજા ચરણે (બીજા ત્રિમાસિક) પહોંચ્યું. AMJ 2023 પહેલા ના 3 ત્રિમાસિક સિઝન માં જે JFM ONI -0.4ºC, FMA ONI -0.1ºC અને MAM 2023 ONI +0.2ºC હતા જે Enso Neutral હતા. બીજા ત્રિમાસિક સીઝન El Nino થ્રેશ હોલ્ડે પહોંચ્યું હોય NOAA ના નિયમો મુજબ હવે આવા 3 મહિના El Nino થ્રેશ હોલ્ડ સળંગ જળવાય રહેવો જોઈએ તો વહેલા માં વહેલું ઓક્ટોબર 2023 માં વિધિવત El Nino પ્રસ્થાપિત થઇ શકે. ત્યાં સુધી માં ઇન્ડિયા નું ચોમાસુ સપ્ટેમ્બર 2023 માં પૂરું થઇ જશે. El Nino સાથે સંકળાયેલ પરિબળ SOI છે. SOI મે મહિના આખર માં નેગેટિવ ઝોન માં હતું પરંતુ જૂન આખર માં SOI ન્યુટ્રલ ઝોન માં હતું જે જુલાઈ માં SOI નેગેટિવ તરફ આગળ વધેલ છે. એલ નિનો માટે SOI નેગેટિવ ઝોન માં હોવું જરૂરી છે. પ્રશાંત મહાસાગર અને તેની ઉપર નું વાતાવરણ હજુ સંપૂર્ણ રીતે જોડાયેલા ના હતા જે હવે જોડાવા પ્રયત્ન કરે છે, જેમ કે El Nino ઘટનાઓ દરમિયાન થાય 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. 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.

દક્ષિણ પશ્ચિમ ચોમાસુ 2023 ની પ્રગતિ સમગ્ર દેશ લેવલ માં જોઈએ તો ધારણા કરતા ઘણી સારી છે. ઉપર આપેલ ગ્રાફ જોવો જે 3 ઓગસ્ટ સુધી ના વરસાદ ની હકીકત દર્શાવે છે. જુલાઈ માં એલ નિનો બીજા ત્રિમાસિક ચરણ માં પહોંચ્યું હોવા છતાં જુલાઈ મહિના માં દેશ લેવલ માં નોર્મલ થી વધુ વરસાદ નોંધાયેલ છે. તેમ છતાં કેરળ, બિહાર, ઝારખંડ માં વરસાદ ની મોટી ઘટ રહી છે જયારે ગુજરાત, રાજસ્થાન, પંજાબ, હરિયાણા, હિમાચલ પ્રદેશ, જમ્મુ કાશ્મીર, લડાખ અને તેલંગાણા માં નોર્મલ થી ઘણો વધુ વરસાદ નોંધાયેલ 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
Second El Nino Thresh Hold Has Been Achieved End Of July 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   28.30   27.29    1.00

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

Summary by: Climate Prediction Center / NCEP  Dated 31st July 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 weak El Niño conditions.
There is a greater than 90% chance that El Niño will continue through the Northern Hemisphere winter.*

* 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.

Recent (preliminary) Southern Oscillation Index values as per The Long Paddock – Queensland Government.

30 Days average SOI was -3.32 at the end of July 2023 and was -6.39 on 4th August 2023 as per The Long Paddock – Queensland Government and 90 Days average SOI was -7.99 on 4th August 2023. The SOI is now moving from neutral zone towards negative zone.

Southern Oscillation Index

As per BOM, Australia

The 30-day Southern Oscillation Index (SOI) for the period ending 30 July 2023 was −4.3, with the value decreasing from +3.9 over the past fortnight. The 60-day SOI and the 90-day SOI were −2.7 and −7.9, respectively. Both the 30-day SOI is moving from neutral zone towards negative zone.
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 1st August 2023