Molecular-Specific Aromatic Compounds Absorption Drives Divergent Radiative Forcing in High-Altitude Air and Snow
Xinyuan Wu1,2,3, Zining Zou4, Yaoyin Zhang5
1Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, P. R. China.
Environmental Science & Technology
|February 9, 2026
Summary
Aromatic compounds in Tibetan Plateau PM2.5 impact climate through atmospheric heating and snow darkening. Their radiative forcing varies seasonally, influenced by biomass burning and cloud interactions.
Area of Science:
- Atmospheric Chemistry
- Climate Science
- Aerosol Physics
Background:
- Aromatic compounds (ACs) are significant brown carbon components influencing Earth's radiative balance.
- Radiative forcing of ACs in high-elevation regions like the Tibetan Plateau (TP) is not well understood.
- PM2.5 samples collected at Mt. Gongga, TP, were analyzed for ACs.
Purpose of the Study:
- To characterize year-round concentrations and optical properties of ACs (nitrated phenols, PAHs, NPAHs) in PM2.5.
- To quantify the direct radiative forcing (DRF) of ACs under clear-sky and all-sky conditions.
- To assess the impact of AC deposition on snow radiative forcing.
Main Methods:
- Year-round sampling of PM2.5 at Mt. Gongga, Tibetan Plateau.
- Chemical characterization of aromatic compounds (NPs, PAHs, NPAHs).
- Measurement of mass absorption coefficients (MAC365) and calculation of radiative forcing.
Main Results:
- AC concentrations were higher in the dry season, but MAC365 peaked in the wet season.
- Clear-sky DRF was positive, stronger in the dry season (6.8 × 10⁻³ W m⁻²).
- AC deposition significantly increased snow radiative forcing (~19-fold) during the dry season.
Conclusions:
- Trace ACs over the TP exert dual radiative impacts: atmospheric heating and cryospheric forcing.
- Cloud modulation and long-range biomass-burning transport influence AC radiative effects.
- Understanding ACs is crucial for accurate climate modeling in high-elevation areas.
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