EFFECT OF DUST ON MONSOON
CONTEXT
Recently, a study details how the Indian monsoon gets influenced by the atmospheric dust particles swept up by winds from deserts in the Middle East (Asian Deserts).
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Dust is very small dry particles of earth or sand.
o PM10 and PM2.5 refers to dust classified by the size of particles.
The natural erosion of soil, sand and rock is the most common source of dust.
Dust emission is common in urban areas from a range of activities such as gardening, to large scale industrial operations.
It is known to influence monsoons, hurricanes and even fertilize rainforests.
The dust emission scheme is extremely sensitive to climate change and understanding these mechanisms and effects of dust can help understand our monsoon systems in the face of global climate change.
Dust storms 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.
EFFECT OF DUST ON MONSOON
Dust from the Middle East [West Asia] and also from the Iranian Plateau also influences the Indian Summer Monsoon (South West Monsoon).
o 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].
Reverse Effect – Indian Summer Monsoon has a reverse effect and can increase the winds in West Asia to produce yet more dust.
o A strong monsoon can also transport air to West Asia and again pick up a lot of dust.
Effect of Anthropogenic Dust – There is a difference of opinion, some studies found that 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.
o Aerosols are defined as a combination of liquid or solid particles suspended in a gaseous or liquid environment.
o Anthropogenic aerosols include sulfate, nitrate, and carbonaceous aerosols, and are mainly from fossil fuel combustion sources.
o However, a recent study showed that they can strengthen Indian summer monsoon rainfall.
Aerosol particles, such as dust, play an important role in the precipitation process, providing the nuclei upon which condensation and freezing take place.
Role of Deserts in Monsoon – Deserts across the globe play important roles in monsoons.
o 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.
o In the southwest United States, there are some small deserts that influence the North African monsoon.