Monsoon Updates

How Asian desert dust enhances Indian summer monsoon?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Indian Monsson : Onset and Withdrawal

Mains level : Determinants of Indian Monsoon

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

Try this PYQ:

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 characterized by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
  2. An IOD phenomenon can influence an El Nino’s impact on the monsoon.

Select the correct Option using the code given below:

(a) Only 1

(b) Only 2

(c) Both 1 and 2

(d) Neither 1 nor 2

Why study dust?

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

Impact of dust on Indian Monsoon

  • 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.

Role of the Iranian plateau

  • Not just the dust from the Middle East, 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.
  • 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.

Transported aerosols

  • 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, we have some small deserts that influence the North African monsoon.

Anthropogenic contributions

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

Minor components

  • Earlier it was believed that dust from deserts across the globe will have the same components.
  • But it was found that different deserts have different chemical compositions and this can influence the dust’s properties.
  • For example, dust from the Middle East has the more absorbing ability of solar radiation than dust from North Africa and this difference in absorbing ability might influence monsoon systems.
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