GS PAPER I: Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location-changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.

Context: A new study now details how dust coming from the deserts in the West, Central and East Asia plays an important role in the Indian Summer Monsoon.

Introduction: Carl Sagan once described Earth as a ‘small speck of dust’, a seemingly insignificant tiny particle.

• But dust has incredible power: it is known to influence monsoons, hurricanes and even fertilize rainforests.

Reverse effect

• The researchers also explain how the Indian Summer Monsoon has a reverse effect and can increase the winds in West Asia to produce yet more dust.
• Dust swarms from the desert when lifted by strong winds can absorb solar radiation and become hot.
• This can cause heating of the atmosphere, change the air pressure, wind circulation patterns, influence moisture transport and increase precipitation and rainfall.
• A strong monsoon can also transport air to West Asia and again pick up a lot of dust. The researchers say this is a positive feedback loop.
• Not just the dust from the Middle East [West Asia], the Iranian Plateau also influences the Indian Summer Monsoon.
• The hot air over the Iranian Plateau can heat the atmosphere over the plateau, strengthen the circulation over the deserts of the Arabian Peninsula and increase dust emission from the Middle East [West Asia].

Aerosols transported

• Deserts across the globe play important roles in monsoons.
• The dust aerosols from deserts in West China such as the Taklamakan desert and the Gobi Desert can be transported eastward to eastern China and can influence the East Asia summer monsoon.
• And in the southwest United States, some small deserts influence the North African monsoon.

Can anthropogenic dust from vehicles, mining, construction can influence monsoons?

• Some studies have found that the anthropogenic aerosols emitted from the Indian subcontinent can decrease summer monsoon precipitation, while others found that absorbing aerosols such as dust can strengthen the monsoon circulation.

Why study dust?

• Many studies have shown that the dust emission scheme is extremely sensitive to climate change and the understanding these mechanisms and effects of dust will help understand our monsoon systems in the face of global climate change.

https://www.thehindu.com/sci-tech/science/how-asian-desert-dust-enhances-indian-summer-monsoon/article34232324.ece?homepage=true

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