How Middle East Dust Intensifies Summer Monsoons on Indian Subcontinent  News
Date:2021-03-31   Source:[美国] Desert News

"We know that dust coming from the desert, when lifted by strong winds into the atmosphere, can absorb solar radiation," said lead author Qinjian Jin, lecturer and academic program associate with KU's Department of Geography & Atmospheric Science. "The dust, after absorbing solar radiation, becomes very hot. These dust particles suspended in the atmosphere can heat the atmosphere enough that the air pressure will change -- and it can result in changes in the circulation patterns, like the winds."

This phenomenon, dubbed an "elevated heat pump," drives moisture onto the Indian subcontinent from the sea.

"The Indian summer monsoon is characterized by strong winds in the summer," Jin said. "So once the winds change, the moisture transport from ocean to land will change, and consequently they will increase the precipitation. The precipitation is very important for people living in South Asia, especially India, and important for agriculture and drinkable water."

While the dust from the Middle East boosts the power of the monsoons on the Indian subcontinent, there is also a reverse effect that results in a positive feedback loop where the monsoons can increase the winds in the Middle East to produce yet more dust aerosols.

"The monsoon can influence dust emission," Jin said. "When we have a stronger monsoon, we have heating in the upper atmosphere. The convection associated with the monsoon can go up to a very high elevation, as much as 10 kilometers. When this pattern of air over the monsoon is heated, you produce something like a wave. Across the area, you'll have high pressure, then low pressure, then high pressure. Those waves can transport air to the Middle East. The air comes upward over the Indian subcontinent, then goes to the Middle East and goes downward -- and when the downward air strikes the surface, it can pick up a lot of dust aerosols."

Jin's co-authors on the paper are Bing Pu, assistant professor of geography & atmospheric science at KU; Jiangfeng Wei of the Nanjing University of Information Science and Technology in Nanjing, Jiangsu, China; William K.M. Lau of the University of Maryland and Chien Wang of Laboratoire d'Aerologie, CNRS/UPS, Toulouse, France.

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