Will the Indian Ocean Dipole save the monsoon?”

Source: The post is based on the article “Will the Indian Ocean Dipole save the monsoon?” published in “The Times of India” on 29th June 2023. 

Syllabus: GS 1 – Indian geography 

News: The Indian Meteorological Department (IMD) has predicted a normal monsoon despite forecasts of an El Nino event. El Nino typically leads to a deficit monsoon, but this occurs only around 60% of the time.  

What factors contribute to the complex relationship between El Nino and the monsoon? 

El Nino flavours: Every El Nino is not the same. They differ in terms of where the warm waters appear in the tropical Pacific. An El Nino with warming around the Dateline is referred to as a Dateline El Nino or a Central Pacific El Nino. It is considered to have a larger negative impact on the monsoon, but an exception was 2005 El Nino. An El Nino with stronger warming around the central Pacific is called Canonical El Nino.  

Indian Ocean Dipole: it is thought to have mitigated the impact of El Nino in 1997. But the cause-and-effect relationship between monsoon and Indian Ocean Dipole is not clearly understood. 

Atlantic Nino: It is a similar east-west anomaly pattern in the tropical Atlantic. It also influences the monsoon. 

What are the limitations of forecasting models? 

Models cannot reliably forecast Indian Ocean Dipole and Atlantic Nino. So, their potential role in the evolution of monsoons this season is not completely known. 

Models predicting El Nino cannot confidently forecast exactly where the warming will be or how strong the warming will be in the early part of an El Nino event. But early indicators suggest that the El Nino of 2023 may evolve to become a Canonical El Nino. 

Why has the significance of seasonal total rainfall diminished? 

Every aspect of the monsoon has been disturbed the global warming. Even a deficit monsoon comes with large-scale extreme rainfall events and heavy rainfall events are increasing over the dry regions of north-western India. 

What compensations could occur this season to reduce the impacts of El Nino? 

The Arabian Sea has warmed since January by almost 1.5°C which could offset the impact. 

Other factors which may compensate are the Eurasian snow cover and the warm Arctic.