The mystery of India’s erratic monsoon can be found in the Indian ocean

Farmers cultivating before transplanting the first paddy crop of the monsoon season in the Sitapura Village in the Mandya district of Karnataka on Aug 11, 2018IANS

  • Scientists at MIT have found that the ocean is partly responsible for the intensity of the Indian monsoon.
  • The ocean heat transporting mechanism may be a new knob in controlling the seasonal South Asian monsoon, as well as other monsoon systems around the world.
  • Understanding the role of the ocean is a step towards understanding how the Indian monsoon is one the most intense climate events in the world.
If not for the Himalayas, India would have been a cold desert. This great mountain range has also been taking blame for the notoriously unpredictable Indian monsoons. Not anymore.

Scientists at the Massachusetts Institute of Technology (MIT) seem to have found that oceans have a role to play in deciding the fate of its unpredictable rains.

The Indian ocean and the mountains working in tandem might be the reason why the Indian monsoon is one of the most intense annual climate events in the world, according to the co-authors of the study, John Marshall and Nicholas Lutsko.

What we find is, the ocean’s response plays a huge role in modulating the intensity of the monsoon.

John Marshall, the Cecil and Ida Green Professor of Oceanography at MIT

Hotter with the wind

The very same summer heat that warms up the Indian subcontinent also sends warm winds to sweep across the Indian ocean — up and over South Asia.

As the winds head North, the water beneath pushes south. These waters, which flow south, transport heat, thereby cooling the ocean. This process creates a bigger difference between the temperature of land and the temperature of the ocean.

We initially had a picture that we couldn’t make a monsoon without the Himalayas, which was the established wisdom. But in our model, we had no such barrier, and we were still able to generate a monsoon, and we were excited about that.

Nicholas Lutsko, postdoc at MIT’s Department of Earth

The team of researchers was able to create a model of the Indian monsoon leaving the Himalayas out of the picture altogether — that too on a hunch.

John Marshall and Nicholas Lutsko, co-authors of the study, initially suspected that adding oceans to a monsoon model would decrease its intensity but found the opposite to be true.

One reason the South Asian monsoon is so strong is there’s this big barrier to the north keeping the land warm, and there’s an ocean to the south that’s cooling, so it’s perfectly situated to be really strong.

Nicholas Lutsko, postdoc at MIT’s Department of Earth

Looking forward

Lutsko and Marshall plan on using their research to explain why the monsoon system didn’t work when the northern hemisphere of the world used to be much colder.

Their research could also be the key the making more accurate predictions about the monsoon rains as the influence of one more variable has been accounted for.

The ocean heat transporting mechanism may be a new knob in controlling the seasonal South Asian monsoon, as well as other monsoon systems around the world.



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