Enhanced light absorption for solid-state brown carbon from wildfires due to organic and water coatings
Wildfires emit solid-state strongly absorptive brown carbon (solid S-BrC, commonly known as tar ball), critical to Earth's radiation budget and climate, but their highly variable light absorption properties are typically not accounted for in climate models. Here, we show that from a Pacific Northwest wildfire, over 90% of particles are solid S-BrC with a mean refractive index of 1.49 + 0.056i at 550 nm. Model sensitivity studies show refractive index variation can cause a ~200% difference in regional absorption aerosol optical depth. We show that ~50% of solid S-BrC particles from this sample uptake water above 97% relative humidity. We hypothesize these results from a hygroscopic organic coating, potentially facilitating solid S-BrC as nuclei for cloud droplets. This water uptake doubles absorption at 550 nm and the organic coating on solid S-BrC can lead to even higher absorption enhancements than water. Incorporating solid S-BrC and water interactions should improve Earth's radiation budget predictions.
Authors
- Amna Ijaz (ORCID: https://orcid.org/0000-0001-8727-7739)
- Zezhen Cheng (ORCID: https://orcid.org/0000-0001-6320-4519)
- Gregory W. Vandergrift (ORCID: https://orcid.org/0000-0002-8962-9897)
- Daniel P. Veghte
- K.-P. Tseng (ORCID: https://orcid.org/0000-0002-1487-5137)
- Kaitlyn J. Suski (ORCID: https://orcid.org/0000-0001-5183-7335)
- Manish Shrivastava (ORCID: https://orcid.org/0000-0002-9053-2400)
- Swarup China (ORCID: https://orcid.org/0000-0001-7670-335X)
- Nurun Nahar Lata (ORCID: https://orcid.org/0000-0003-1466-3545)
- Alla Zelenyuk (ORCID: https://orcid.org/0000-0002-0674-0910)
- Jerome D. Fast (ORCID: https://orcid.org/0000-0002-2006-5675)
- William Kew (ORCID: https://orcid.org/0000-0002-4281-4630)
- Gourihar Kulkarni (ORCID: https://orcid.org/0000-0001-8069-4281)
- Larry K. Berg (ORCID: https://orcid.org/0000-0002-3362-9492)
- Lynn Rebecca Mazzoleni (ORCID: https://orcid.org/0000-0002-0226-7337)
- Johannes Weis (ORCID: https://orcid.org/0000-0002-9802-6174)
- Libor Kovarik
Institutions
- Michigan Technological University (US)
- Pacific Northwest National Laboratory (US)
- Lawrence Berkeley National Laboratory (US)
- University of Illinois Urbana-Champaign (US)
- The Aerospace Corporation (US)
- Environmental Molecular Sciences Laboratory (US)
- The Ohio State University (US)
Publication Details
- Journal
- Nature Communications
- Published
- 2024-11-28
- DOI
- https://doi.org/10.1038/s41467-024-54506-5
- Citations
- 14
- Primary Topic
- Atmospheric chemistry and aerosols
- Type
- article
- Field-Weighted Citation Impact
- 5.27
Funders
- U.S. Department of Energy
- Office of Science
- Biological and Environmental Research