With reference to 'Indian Ocean Dipole (IOD)' sometimes mentioned in the news while forecasting Indian monsoon which of the following statements is/are correct?

1. IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.

2. An IOD phenomenon can influence an EI Nino's impact on the monsoon.

Select the correct answer using the code given below:

The correct answer is 2 only.

Indian Ocean Dipole (IOD)

• It is the difference in sea surface temperature between two poles or areas (hence a dipole) i.e. an eastern pole in the eastern Indian Ocean south of Indonesia, and a western pole in the Arabian Sea (western Indian Ocean). Hence, statement 1 is not correct.
• The IOD affects the climate of countries that surround the Indian Ocean Basin like India, Australia and others, and is a significant contributor to rainfall variability in this region. 
• The IOD, in scientific terms, is a coupled ocean and atmosphere phenomenon, similar to El Nino–Southern Oscillation (ENSO) but in the equatorial Indian Ocean.
• 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), it is thought that the IOD has a link with ENSO events.
  • Hence, negative IOD events are often associated with La Nina and positive events with El Nino. Hence, statement 2 is correct.