Context

Rainfall over the Southern peninsular region has been deficient so far.

About

• India actually has two monsoons -
  • the southwest monsoon
  • the northeast monsoon
• Southwest monsoon: The southwest monsoon, which is the main monsoon, comes in from the sea and starts making its way up India’s west coast in early June.
  • By mid-July, most of the country is covered in rain. This gradually starts clearing from most places in northwest India by October.
• Northeast monsoon: Also called the winter monsoon, the northeast monsoon affects India’s east coast during November and December.
  • It is a short but intense monsoon.
  • Major States receiving NE Monsoon: The states of Tamil Nadu, Karnataka, and Kerala receive most of their rainfall from the northeast monsoon, while the rest of the country receives most of its rainfall from the southwest monsoon.
  • Influences: Northeast Monsoon is influenced by global climate parameters such as ENSO (El Nino – Southern Oscillation), IOD (Indian Ocean Dipole) and MJO (Madden Julian Oscillation).
• The northeast Indian monsoon (NEM) season is usually defined by the calendar months of October–December (OND), when there is significant rainfall in the southeastern part of peninsular India.

Why is the rainfall deficient this season?

La Niña

• The deficiency of rainfall is linked it to the prevailing La Niña conditions in the Pacific Ocean.
• While El Niño (Spanish for ‘little boy’), is the abnormal surface warming observed along the eastern and central regions of the Pacific Ocean (region between Peru and Papua New Guinea), La Niña (Spanish for ‘little girl’) is an abnormal cooling of these surface waters.
• Together, the El Niño and La Niña phenomena are termed as El Niño Southern Oscillation (ENSO).
• These are large-scale ocean phenomena which inflence the global weather — winds, temperature and rainfall.
• They have the ability to trigger extreme weather events like droughts, floods, hot and cold conditions, globally.
• Each cycle can last anywhere between 9 to 12 months, at times extendable to 18 months — and re-occur after every three to five years.
• Meteorologists record the sea surface temperatures for four different regions, known as Niño regions, along this equatorial belt.
• Depending on the temperatures, they forecast either as an El Niño, an ENSO neutral phase, or a La Niña.