Source-explicit estimation of brown carbon in the polluted atmosphere over the North China Plain: implications for distribution, absorption, and the direct radiative effect
<p>Brown carbon (BrC) plays a significant role in altering atmospheric radiation. Beyond biomass and biofuel combustion, recent studies identify fossil fuel sources – especially residential coal burning and vehicle exhaust – as major contributors to BrC. This underscores a gap in climate model...
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/7563/2025/acp-25-7563-2025.pdf |
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| Summary: | <p>Brown carbon (BrC) plays a significant role in altering atmospheric radiation. Beyond biomass and biofuel combustion, recent studies identify fossil fuel sources – especially residential coal burning and vehicle exhaust – as major contributors to BrC. This underscores a gap in climate models, which often assume fossil fuel organic aerosols (OAs) are non-absorbing or treat all OA as light-scattering. In this study, we simulate BrC over the North China Plain (NCP) during a winter pollution event using the WRF-Chem model, incorporating explicit BrC absorption properties. The model aligns well with observed pollutant and aerosol levels, revealing an average near-surface BrC concentration of 5.2 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span>, contributing 16.4 % to aerosol absorption at 365 nm. Using a diagnostic adjoint approach, we estimate that BrC exerts a direct radiative effect (DRE) averaging <span class="inline-formula">−</span>0.09 W m<span class="inline-formula"><sup>−2</sup></span> at the top of the atmosphere, reducing the cooling effect of organic carbon by 28.0 % and producing a local warming effect of up to <span class="inline-formula">+</span>0.40 W m<span class="inline-formula"><sup>−2</sup></span>. Coal combustion is the largest BrC source in the NCP in 2014, though secondary BrC also significantly impacts the regional radiation balance.</p> |
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| ISSN: | 1680-7316 1680-7324 |