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ENSO, IOD, MJO, and India’s Weather: What You Need to Know

El Nino effect
Natural disaster cartoon composition with outdoor landscape with dry tree and hot sands vector illustration

Introduction

El Nio-Southern Oscillation (ENSO), one of the major elements determining India’s climate, is one of the natural phenomena that have an impact on the country’s weather patterns. The primary cause of this phenomenon is thought to be shifts in global rainfall patterns. Contrarily, the Indian Ocean Dipole (IOD) and the Madden-Julian Oscillation (MJO) have a significant impact on India’s weather. In this post, we shall examine these occurrences and how they affect India’s weather forecast.

El Nio and La Nina:

El Nino

In areas of South America, the southern United States, the Horn of Africa, and some regions of Central Asia, El Nio episodes often result in an increase in rainfall. On the other side, extreme droughts in Australia, Indonesia, Southeast Asia, and northern South America may be brought on by La Nia occurrences. It’s crucial to remember that no two El Nio events are alike, and occasionally, substantial variances can occur that can cause unanticipated weather shifts.

ENSO News:

Starting from February 2023, we’ve witnessed significant fluctuations in sea surface temperatures (SST) within the central equatorial Pacific Ocean. In February, these anomalies were registering at a half-degree below the average, but by the time May rolled around, they had surged to more than half a degree above the norm. As of the latest data, the entire Nio region is experiencing temperatures over one degree Celsius warmer than usual. Over the past fortnight, the Nio 3.4 region, which serves as an indicator for El Nio, has consistently recorded temperatures 1.6 degrees Celsius above the normal range.

These fluctuations initially raised uncertainties, mainly stemming from the unstable interaction between ocean waters and the atmosphere. Despite nearing the conclusion of the monsoon season, it appears that the die has already been cast. The ongoing El Nio event has unleashed substantial climatic impacts, setting off reactions in the atmosphere. In August 2023, the Southern Oscillation Index (SOI) plummeted from +0.3 in June to -0.3 in July. This decline is primarily attributed to the disruption of atmospheric pressure patterns caused by the warming of the ocean’s surface. Alterations in the strength of the trade winds and their weakening are contributing factors to the changes in pressure across the tropical Pacific Ocean.”

Status of the Indian Ocean Dipole (IOD):

IOD

On September 10, 2023, the IOD index for the previous week was 1.13 degrees Celsius. This positive IOD index has increased from +0.79 degrees Celsius on August 21, 2023, to 1.05 degrees Celsius on September 5, 2023, and is now above the threshold (+0.4 degrees Celsius) for the fourth week in a row. The possibility of a positive IOD event this year is indicated by the growing positive IOD index. A prolonged positive IOD event is one in which the index remains over the cutoff for eight weeks or more. The negative effects of El Nio are typically lessened by a favorable IOD event.


Madden-Julian Oscillation (MJO): 

MJO - Madden-Julian Oscillation

The Indian Ocean’s equatorial region was traversed by a modest MJO pulse. There is still uncertainty in dynamic models on the direction and size of the MJO. For the next two weeks, the Global Forecast System (GFS) predicts that a weak MJO with amplitude in phases 2 and 3 will provide support. This might increase the amount of rain that falls during the monsoon in central and eastern India, thus reducing rainfall deficits.


Conclusion: 

Rain will continue across Madhya Pradesh, Maharashtra, Gujarat, and eastern and southern Rajasthan due to the ongoing meteorological activity linked to the outlined low-pressure region that initially formed over the Bay of Bengal. Rajasthan may have a delayed start to the southwest monsoon’s exit. Close observation and readiness are required due to the changing climate signals and their effects on India’s weather forecast.

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