The Roller­coaster that was the 2023 monsoon

Context:

• India’s 2023 monsoon rainfall hit five-year low due to the El Nino weather pattern, affecting the agricultural production.

More about the news: 

• As per the India Meteorological Department (IMD), rainfall over the country during June to September was 94% of its long period average, the lowest since 2018.

Chart 1: It shows the cumulative departure (in %) of rainfall from the Long Period Average (LPA) in India this monsoon season.

• The LPA is the average rainfall received between 1971 and 2020. 
• Departure of ­20% or lower points to deficient rainfall, departure of +20% or higher points to surplus rainfall, and anything in between is considered normal. 
• There was a severe deficit in the first two weeks of June, which was compensated in July, and a severely dry August was later compensated in September, leading to a “normal” monsoon in the end.

Chart 2:

• The monthly percentage departure of rainfall from the LPA in India was ­9% in June, +13% in July, ­36% in August, and +13% in September.
• Region wise split of the monthly departure:  The northwest region received excess rainfall (>+19% departure) in the first two months of the monsoon, though it ran a deficit in August. 

Map 3:

• It shows the meteorological sub division wise percentage departure of rainfall from the LPA in India at the end of the monsoon season. 
• The sub­divisions — eastern Uttar Pradesh, Bihar, Jharkhand, Gangetic West Bengal, south­interior Karnataka and Kerala — ended with a deficient rainfall. 
• The subdivisions Saurashtra & Kutch, and West Rajasthan ended with a surplus rainfall. The rest of India recorded a normal rainfall (within the +19% and ­19% range).

Chart 4:

• The impact El Nino and La Nina had on the percentage departure of rainfall from the LPA in the southwest monsoons between the 1950s and 2023. 
  • El Nino is a warming of Pacific waters that is typically accompanied by drier conditions over the Indian subcontinent.
  • La Nina is a climate pattern that describes the periodic cooling of sea surface temperatures in the eastern and central Pacific that is associated with surplus rain in India.