Indian scientists have discovered a hitherto unknown effect of the tropical weather phenomenon known as Madden-Julian Oscillation (MJO), which plays an important role in determining the fate of Indian summer monsoon.
The scientists have now found that when winds of MJO reach eastern Indian Ocean, particularly over the North West Australian Basin, its energy gets transferred down to the ocean bottom, leading to an oscillation of the entire water column.
This results in an inter-play of underlying topography of the basin and non-uniform density of seawater across the water column. It subsequently gets radiated out through fast-moving ocean waves that eventually invade the entire tropical Indian Ocean within some hours.
These waves carry a lot of energy and momentum. The kinetic energy contained within the North Indian Ocean due to these waves is about 20 Peta Joules – similar to explosion of hundreds of atomic bombs.
The scientists have found that the sea level in the Indian Ocean rises and falls by up to four cm every 30 to 80 days because of the movement of the water column. In addition, the rise and fall of sea level leads to exchange of as much as three trillion tons of water between the Indian Ocean and the Pacific Ocean.
Such large mass exchange can influence polar motion of the earth and length of the day, whose variability is of utmost importance to the accuracy of the Global Positioning System (GPS).
Reference- India Science Wire story, Climate.gov website