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Photochemical degradation affects the light absorption of water-soluble brown carbon in the South Asian outflow

Dasari, Sanjeev and Andersson, August and Bikkina, Srinivas and Holmstrand, Henry and Budhavant, Krishnakant and Satheesh, Sreedharan and Asmi, Eija and Kesti, Jutta and Backman, John and Salam, Abdus and Bisht, Deewan Singh and Tiwari, Suresh and Hameed, Zahid and Gustafsson, Orjan (2019) Photochemical degradation affects the light absorption of water-soluble brown carbon in the South Asian outflow. In: SCIENCE ADVANCES, 5 (1).

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Official URL: https://doi.org/10.1126/sciadv.aau8066


Light-absorbing organic aerosols, known as brown carbon (BrC), counteract the overall cooling effect of aerosols on Earth's climate. The spatial and temporal dynamics of their light-absorbing properties are poorly constrained and unaccounted for in climate models, because of limited ambient observations. We combine carbon isotope forensics (delta C-13) with measurements of light absorption in a conceptual aging model to constrain the loss of light absorptivity (i.e., bleaching) of water-soluble BrC (WS-BrC) aerosols in one of the world's largest BrC emission regions-South Asia. On this regional scale, we find that atmospheric photochemical oxidation reduces the light absorption of WS-BrC by similar to 84% during transport over 6000 km in the Indo-Gangetic Plain, with an ambient first-order bleaching rate of 0.20 +/- 0.05 day(-1) during over-ocean transit across Bay of Bengal to an Indian Ocean receptor site. This study facilitates dynamic parameterization of WS-BrC absorption properties, thereby constraining BrC climate impact over South Asia.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to AMER ASSOC ADVANCEMENT SCIENCE
Department/Centre: Division of Mechanical Sciences > Divecha Centre for Climate Change
Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 21 Feb 2019 04:50
Last Modified: 21 Feb 2019 04:50
URI: http://eprints.iisc.ac.in/id/eprint/61773

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