Dust and Indian Monsoon

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Recently, a study has shown details on how dust coming from the deserts in the West, Central and East Asia plays an important role in the Indian Summer Monsoon.

Key Highlights of the Study

• Dust
  • Dusts are solid particles, ranging in size from below 1 µm up to at least 100 µm, which may be or become airborne, depending on their origin, physical characteristics and ambient conditions.
  • It may occur naturally (pollens, volcanic ashes and sandstorms) and is also generated by anthropogenic factors (vehicles, mining, construction, etc.) like work processes generating chemical, mineral, metallic dusts, etc.
• Effects Natural Dust on Monsoon
  • Dust is lifted by strong winds and 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.
  • Due to the vast amount of dust along with the sand, deserts play an important role 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.
    • Scientists are also planning to study the mineral components of desert dust aerosols as different desert dust have different chemical compositions which can influence the dust’s properties.
    • For example, as per the scientists, dust from the Middle East (West Asia) has more absorbing ability of solar radiation than dust from North Africa and this difference might influence monsoon systems.
• Effects of Anthropogenic Dust on Monsoon
  • Studies have found that absorbing aerosols such as dust can strengthen the monsoon circulation.
    • In the latest study, scientists used the climate model to simulate the impact of anthropogenic aerosols on India and the results showed that they can strengthen Indian summer monsoon rainfall.
• Effects on Indian Monsoon
  • Dust from the Middle East (West Asia) as well as from the Iranian Plateau influences the Indian Summer Monsoon.
  • The hot air over the Iranian Plateau heats the atmosphere over the plateau, strengthens the circulation over the deserts of the Arabian Peninsula and increases dust emission from the Middle East (West Asia).

• Reverse Effect
  • The Indian Summer Monsoon has a reverse effect and can increase the winds in West Asia to produce yet more dust.
  • A strong monsoon can also transport air to West Asia and again pick up a lot of dust, which forms a positive feedback loop.
• Significance
  • Studies have shown that the dust emission is extremely sensitive to climate change and understanding these mechanisms and effects of dust will help understand the Indian monsoon systems in the face of global climate change.

Source: TH