Explanation:

• Indian Ocean Dipole (IOD), sometimes referred to as the Indian Nino, plays out in the relatively smaller area of the Indian Ocean between the Indonesian and Malaysian coastline in the east and the African coastline near Somalia in the west. One side of the ocean, along the equator, gets warmer than the other. IOD is said to be positive when the western side of the Indian Ocean, near the Somalia coast, becomes warmer than the eastern Indian Ocean. It is negative when the western Indian Ocean is cooler. Hence, statement 1 is correct. • The air circulation in the Indian Ocean basin moves from west to east, that is from the African coast towards the Indonesian islands, near the surface, and in the opposite direction at the upper levels. That means the surface waters in the Indian Ocean get pushed from west to east. In a normal year, warmer waters in the western Pacific near Indonesia cross over into the Indian Ocean and make that part of the Indian Ocean slightly warmer. That causes the air to rise and helps the prevailing air circulation. • In the years when the air circulation becomes stronger, warmer surface waters from the African coast are pushed towards the Indonesian islands, making that region warmer than usual. This caused more hot air to rise and the cycle reinforced itself. This is the state of negative IOD. The opposite case involves air circulation becoming slightly weaker than normal. In some rare cases, the air circulation even reverses direction. The consequence is that the African coast becomes warmer while the Indonesian coastline gets cooler. • A positive IOD event is often seen developing at times of an El Nino, while a negative IOD is sometimes associated with La Nina. During El Nino, the Pacific side of Indonesia is cooler than normal because the Indian Ocean side also gets cooler. That helps the development of a positive IOD. • A positive IOD helps rainfall along the African coastline and also over the Indian sub-continent while suppressing rainfall over Indonesia, Southeast Asia, and Australia. The impacts are opposite during a negative IOD event because Negative IOD can lead to increased rainfall and atmospheric convection over the eastern Indian Ocean, Indonesia, and northern Australia. Hence, statement 2 is correct.