Light absorbing atmospheric aerosols (mainly black carbon, brown carbon and mineral dust) and their radiative effects represent cutting edge international research topics in atmospheric sciences. Recently, the research team led by Professor Tian Pengfei from the College of Atmospheric Sciences, Lanzhou University, has made sustained efforts in this field and yielded a set of innovative achievements on quantitative spectral absorption separation, source identification and climate effect assessment of absorbing aerosols. Relevant papers have been successively published in the international journals Environmental Science & Technology, Atmospheric Chemistry and Physics and Atmospheric Environment. Meanwhile, the team has obtained authorization for a national invention patent.

 

Quantifying Spectral Absorption Contributions of Industrial and Natural Mineral Dust

 

Mineral dust is an important light absorbing atmospheric aerosol. Nevertheless, its light absorption contribution has long been underestimated or even misattributed to carbonaceous aerosols in previous observational studies. For urban environments with co existing industrial and natural sources, prior research failed to accurately distinguish spectral absorption characteristics between industrial dust and natural dust. Drawing on three year high resolution observational datasets from the Lanzhou Atmospheric Composition Monitoring Super Site (LACMS), the team innovatively coupled aerosol optical and chemical observations via a receptor model. This enables precise separation of spectral absorption contributions from industrial dust, natural dust and absorbing aerosols of other origins.

 

 

Figure 1. Supplementary Cover of Environmental Science & Technology (ES&T)

 

The study reveals that natural dust contributes up to 12.6% to aerosol absorption at the 370 nm band in spring, while industrial dust accounts for 10.5% in summer. The Absorption Ångström Exponent (AAE) of both dust types exhibits obvious seasonal variations. After accounting for dust spectral absorption, the mass absorption cross section of organic carbon at 370 nm increases substantially by 21%-59%. Published as a cover paper in the top journal Environmental Science & Technology for atmospheric environment research, this work lists Guan Xu, Cuiying Postdoctoral Fellow, as the first author and Professor Tian Pengfei as the corresponding author. Co authors include Professor Yang Shengli from the College of Earth and Environmental Sciences and Professor Zhang Lei from the College of Atmospheric Sciences.

Article link: https://doi.org/10.1021/acs.est.5c17112

 

Developing a New Method for Quantifying Spectral Absorption of Black Carbon and Brown Carbon

 

Traditional approaches for separating absorption contributions of black carbon (BC) and brown carbon (BrC) heavily rely on empirical assumptions. To address this limitation, the team proposed the Tracer Guided Least Square (TGLS) method. Without pre setting the Absorption Ångström Exponent (AAE) for black carbon, this method can accurately retrieve spectral absorption contributions of black carbon and brown carbon (Figure 2). The new method has been successfully applied to observational campaigns in Beijing and Lanzhou. At the Beijing site, the AAE of black carbon is 0.81 and that of brown carbon is 4.89. Brown carbon contributes approximately 19% to carbonaceous aerosol absorption at 405 nm, which rapidly drops to around 1% in the near infrared band. Distinct differences are found at the Lanzhou site: BC AAE is 0.75 and BrC AAE is 5.40, and brown carbon exerts relatively minor influence on spectral absorption. Further analysis demonstrates that the conventional assumption of a fixed BC AAE value of 1.0 introduces systematic biases. Moreover, the radiative forcing of brown carbon is over four fold more sensitive to AAE variations compared with black carbon.

 

 

Figure 2. Flowchart of the Tracer Guided Least Square method for quantitative calculation of black carbon and brown carbon absorption

 

This achievement is published in the classic journal Atmospheric Environment. Wang Wenfang, master’s student of the 2023 intake, serves as the first author. Professor Tian Pengfei and Researcher Wu Yunfei from the Institute of Atmospheric Physics, Chinese Academy of Sciences, are corresponding authors. Co authors include Shi Jinsen, Cao Xianjie, Liang Jiening and Zhang Lei from the College of Atmospheric Sciences, Lanzhou University. Centered on this new method, the team has been granted a national invention patent titled Spectral Absorption Analysis Method for Carbonaceous Aerosols, Electronic Device and Storage Medium. The patent covers quantitative analysis approaches and relevant implementation techniques for carbonaceous aerosol spectral absorption, offering technical support for the application and transformation of scientific research outputs.

Article link: https://doi.org/10.1016/j.atmosenv.2026.121988

 

Quantifying Spectral Absorption Properties and Radiative Effects of Aerosols

 

Adopting the interpretable machine learning method SHAP (SHapley Additive exPlanations), combined with ground based observations and multi year atmospheric column retrieval datasets from Beijing and Lanzhou, the team systematically quantifies relationships between chemical composition, particle size distribution and aerosol AAE, and evaluates the response of radiative forcing to AAE. Results show that chemical components exert far stronger control over atmospheric column AAE variations than particle size parameters. In Beijing, coarse mode absorbing dust, brown carbon and black carbon contribute 18.9%, 18.5% and 13.9% respectively to the prediction of atmospheric column AAE, with chemical components contributing approximately 65% in total. For Lanzhou, the respective importance values of brown carbon, coarse mode absorbing dust and black carbon are 19.4%, 17.4% and 17.3%, and chemical components contribute around 68% cumulatively (Figure 3). Near surface observations indicate that elevated near surface AAE in Beijing is mainly associated with increased fine dust and decreased non dust water soluble ions, whereas near surface AAE over Lanzhou is predominantly governed by dust.

 

 

Figure 3. Interpretation of aerosol AAE parameters via machine learning models

 

Further SHAP analysis reveals that atmospheric column AAE possesses high explanatory power for predicting top of atmosphere direct radiative forcing. Given fixed total aerosol loadings, atmospheric column AAE becomes the dominant factor modulating predicted radiative forcing efficiency for both Beijing and Lanzhou, each contributing roughly 40%. This study provides systematic observational evidence for parameterizing aerosol absorption properties within climate models and delivers critical references for reducing uncertainties in radiative effect assessment.

Published in the top journal Atmospheric Chemistry and Physics in atmospheric chemistry physics research, this paper lists Wang Wenfang (2023 entry master’s student) as first author. Professor Tian Pengfei and Chen Min from the College of Atmospheric Sciences act as corresponding authors. Co authors include Researcher Wu Yunfei (Institute of Atmospheric Physics, CAS) and Professor Zhang Lei (College of Atmospheric Sciences, Lanzhou University).

Article link: https://doi.org/10.5194/acp 26 6471 2026

 

This series of studies was supported by the Pioneer Project for Disciplinary Breakthroughs in Western Ecological Security, General Programs of the National Natural Science Foundation of China, Gansu Longyuan Youth Elite Fund, Outstanding Young Scholar Support Program of the Fundamental Research Funds for the Central Universities of Lanzhou University, and Gansu Provincial University Graduate “Innovation Star” Project. Focusing on the typical co existence of anthropogenic pollution and natural dust across the semi arid region of Northwest China, Professor Tian Pengfei’s team addresses key scientific challenges including quantitative separation of aerosol spectral absorption and climate effect assessment. It has built a systematic research framework spanning methodological innovation, mechanism interpretation and radiative effect evaluation, and enhanced Lanzhou University’s international standing in studies on atmospheric aerosols and their climatic impacts.

 

Written by: Tian Pengfei, Guan Xu, Wang Wenfang

Figures by: Guan Xu, Wang Wenfang

Edited by: Zhang Tingting