Air purifier and pollution pump: the Indian monsoon

HALO research aircraft with measuring instruments from KIT has crossed monsoon – results published in Science
Schmutzwolke über Südasien: Die „Atmospheric Brown Cloud“ entsteht während der Wintermonate durch das Verbrennen von Biomasse und fossilen Brennstoffen. (Foto: NASA/Earth Observatory) NASA/Earth Observatory
Pollution cloud over South Asia: combustion of biomass and fossil fuels regularly causes the appearance of “atmospheric brown clouds”.. (Photo: NASA/Earth Observatory)

To examine the interaction between air pollution and the South Asian monsoon, scientists have covered 100,000 kilometers in an aircraft mission. Measuring devices from Karlsruhe Institute of Technology (KIT) were also on board. The measurement campaign was coordinated by the Max Planck Institute for Chemistry. One of the things the mission showed was that a monsoon cleanses the air of the majority of pollutants but distributes the rest across the entire globe. The complete results are published in Science.

The atmospheric effects of anthropogenic air pollution from the combustion of fossil fuels and biomass during the dry season in South Asia are obvious from satellite images year after year. Between December and March visibly polluted air, also simply referred to as “atmospheric brown cloud” in scientific literature, moves from India across the Indian Ocean. There is no improvement in sight for this situation. In fact, in the last decade, the nitrogen oxide and sulfur dioxide emissions in South Asia have increased by 50 percent. This in turn made scientist wonder even more about what is happening with the pollutants during the South Asian monsoon, in other words in the summer. A monsoon is created as soon as air masses are heated up over the Indian subcontinent during the summer months and the warm air rises. At the same time, moist ocean air is sucked in, resulting in heavy rain and thunderstorms. When this massive weather phenomenon spreads from the Mediterranean to the Pacific from June to October, the brown cloud disappears in its updrafts and thunderstorm systems.

Full Text: Press Release 072/2018


mhe, 15.06.2018