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The warming potential of the small particles is highest close to their sources

The warming potential of the small particles is highest close to their sources

Light-absorbing aerosol particles heat the planet - how much is still uncertain. The warming properties of the particles were experimentally investigated at the source and in background regions in South-Asia. The results were published in January 2019 in the journal Science Advances.

Light-absorbing carbon, the so-called brown carbon, is released from burning wood and other organic matter. A significant fraction of the South-Asian aerosol emissions is brown carbon. It has adverse impacts on climate and human health. The atmospheric aerosols group of the Finnish Meteorological Institute took part in the study in which brown carbon aerosol climate impact was studied both within the source region and further away.

Concurrent measurements in three locations in South-Asian region show what happens to the freshly emitted strongly absorbing carbon aerosol during its atmospheric transport. Aerosol plumes were followed from the highly polluted Indo-Gangetic Plain in Delhi via the Bangladesh Climate Observatory at Bhola to the Maldives Climate Observatory at Hanimaadhoo, in the Indian Ocean.

During this atmospheric transport of over 6.000 km the amount of aerosol dramatically decreased. In addition, the aerosol changed its properties becoming "brighter" and less absorbing with time. This would indicate a decrease in aerosol atmospheric heating. The calculated half-time of the carbon aerosol absorption ability was 3.6 days. However, the result also indicates that the aerosol warming impact is the strongest in the source regions where their concentration is also at its maximum.

These new quantitative results allow for more accurate model prediction of the brown carbon aerosol climate impacts now and in future.

Further information:

Senior Scientist Eija Asmi, Finnish Meteorological Institute, tel. +358 50 390 6638,

Professor Örjan Gustafsson, Stockholm University,

Results were published by the Stockholm University together with various international groups. FMI aerosol group is part of the Maldives Climate Observatory international science team.

S. Dasari, A. Andersson, S. Bikkina, H. Holmstrand, K. Budhavant, S. Satheesh, E. Asmi, J. Kesti, J. Backman, A. Salam, D. S. Bisht, S. Tiwari, Z. Hameed, Ö. Gustafsson, Photochemical degradation affects the light absorption of water-soluble brown carbon in the South Asian outflow. Sci. Adv. 5, eaau8066 (2019).

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