El Nino and Indian Ocean Dipole (IOD)

In Context :

• Southwest monsoon 2022 will be “normal” predicted by private weather forecaster Skymet. 
• El Nino and Indian Ocean Dipole (IOD) are not going to affect it  .

About 

• El Nino:
  • This is a name given to the periodic development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peruvian current.
  • ‘El Nino’ is a Spanish word meaning ‘the child’, and refers to the baby Christ, as this current starts flowing during Christmas.
  •  The presence of the El Nino leads to an increase in sea-surface temperatures and a weakening of the trade winds in the region. 
  • In a normal monsoon year (without El Nino), the pressure distribution along the coast of Peru in South America has a higher pressure than the region near northern Australia and South East Asia.

•  Indian Ocean Dipole (IOD):
  • It is defined by the difference in sea surface temperature between two areas (or poles, hence a dipole) – a western pole in the Arabian Sea (western Indian Ocean) and an eastern pole in the eastern Indian Ocean south of Indonesia. 
  • In scientific terms, the IOD is a coupled ocean and atmosphere phenomenon, similar to ENSO but in the equatorial Indian Ocean.
  •  It is thought that the IOD has a link with ENSO events through an extension of the Walker Circulation to the west and associated Indonesian throughflow (the flow of warm tropical ocean water from the Pacific into the Indian Ocean). 
  • The IOD affects the climate of Australia and other countries that surround the Indian Ocean Basin, and is a significant contributor to rainfall variability in this region.

Source:TH