Format

Send to

Choose Destination
Sci Adv. 2019 Jan 30;5(1):eaau8066. doi: 10.1126/sciadv.aau8066. eCollection 2019 Jan.

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

Author information

1
Department of Environmental Science and Analytical Chemistry (ACES), Bolin Centre for Climate Research, Stockholm University, Stockholm 10691, Sweden.
2
Maldives Climate Observatory at Hanimaadhoo (MCOH), Hanimaadhoo, Republic of the Maldives.
3
Centre for Atmospheric and Oceanic Sciences and Divecha Centre for Climate Change, Indian Institute of Sciences (IISC), Bangalore 560012, India.
4
Atmospheric Composition Unit, Finnish Meteorological Institute (FMI), Helsinki 00560, Finland.
5
Servicio Meteorológico Nacional (SMN), C1425 CABA, Argentina.
6
Department of Chemistry, University of Dhaka, Dhaka 1000, Bangladesh.
7
Indian Institute of Tropical Meteorology (IITM), New Delhi 110008, India.
8
Maldives Meteorological Services (MMS), Hulhule 22000, Republic of Maldives.

Abstract

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 (δ13C) 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 ~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.

Supplemental Content

Full text links

Icon for PubMed Central
Loading ...
Support Center