Preprints
https://doi.org/10.5194/egusphere-2025-4936
https://doi.org/10.5194/egusphere-2025-4936
15 Oct 2025
 | 15 Oct 2025

An Ensemble Machine Learning Method to Retrieve Aerosol Parameters from Ground-based Sun-sky Photometer Measurements

Qiurui Li, Zhongxia Sun, Meijing Liu, Huizheng Che, Yu Zheng, and Jing Li

Abstract. Ground-based Sun-sky photometers have been widely used to measure aerosol optical and microphysical properties, yet the conventional numerical inversion schemes are often computationally expensive. In this study, we developed an explainable Ensemble Machine Learning (EML) model that simultaneously retrieves aerosol single scattering albedo (SSA), scattering asymmetry parameter (g), effective radius (reff), and fine-mode fraction (FMF) from direct and diffuse solar radiation measurements, with feature importance quantified using SHapley Additive exPlanations (SHAP). The EML model was trained and validated on a dataset of 110,000 samples simulated using the T-matrix particle scattering model and the VLIDORT radiative transfer model, encompassing diverse aerosol, atmospheric, and surface conditions. The algorithm demonstrated robustness through ten-fold cross validation, achieving correlation coefficients of 0.94, 0.95, 0.92, and 0.90 for SSA, g, reff, and FMF on the validation set, respectively. SHAP-based feature importance analysis confirmed the physical interpretability of the model, highlighting its effective use of multi-band radiance information and the stronger dependence of SSA retrieval on aerosol optical depth (AOD) relative to g and reff. Retrieval uncertainties estimated from repeated noise perturbation experiments were 0.03 for SSA, 0.02 for g, 0.08 for reff, and 0.09 for FMF. Applied to 132,067 sets of raw photometer measurements, the EML-based retrieval produced forward radiance fitting residuals comparable to those of the AERONET official inversion products. Moreover, compared with numerical algorithms, the EML model eliminates the need for a priori assumptions and smoothness constraints, while improving computational efficiency by more than five orders of magnitude.

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Journal article(s) based on this preprint

16 Apr 2026
An ensemble machine learning method to retrieve aerosol parameters from ground-based Sun-sky photometer measurements
Qiurui Li, Zhongxia Sun, Meijing Liu, Huizheng Che, Yu Zheng, and Jing Li
Atmos. Meas. Tech., 19, 2507–2528, https://doi.org/10.5194/amt-19-2507-2026,https://doi.org/10.5194/amt-19-2507-2026, 2026
Short summary
Qiurui Li, Zhongxia Sun, Meijing Liu, Huizheng Che, Yu Zheng, and Jing Li

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-4936', Anonymous Referee #1, 02 Jan 2026
    • AC1: 'Reply on RC1', Jing Li, 26 Feb 2026
  • RC2: 'Comment on egusphere-2025-4936', Anonymous Referee #2, 28 Jan 2026
    • AC2: 'Reply on RC2', Jing Li, 26 Feb 2026

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-4936', Anonymous Referee #1, 02 Jan 2026
    • AC1: 'Reply on RC1', Jing Li, 26 Feb 2026
  • RC2: 'Comment on egusphere-2025-4936', Anonymous Referee #2, 28 Jan 2026
    • AC2: 'Reply on RC2', Jing Li, 26 Feb 2026

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
AR by Jing Li on behalf of the Authors (01 Mar 2026)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (08 Mar 2026) by Ilias Fountoulakis
RR by Anonymous Referee #1 (21 Mar 2026)
ED: Publish as is (29 Mar 2026) by Ilias Fountoulakis
AR by Jing Li on behalf of the Authors (03 Apr 2026)  Manuscript 

Journal article(s) based on this preprint

16 Apr 2026
An ensemble machine learning method to retrieve aerosol parameters from ground-based Sun-sky photometer measurements
Qiurui Li, Zhongxia Sun, Meijing Liu, Huizheng Che, Yu Zheng, and Jing Li
Atmos. Meas. Tech., 19, 2507–2528, https://doi.org/10.5194/amt-19-2507-2026,https://doi.org/10.5194/amt-19-2507-2026, 2026
Short summary
Qiurui Li, Zhongxia Sun, Meijing Liu, Huizheng Che, Yu Zheng, and Jing Li
Qiurui Li, Zhongxia Sun, Meijing Liu, Huizheng Che, Yu Zheng, and Jing Li

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
We present a fast, interpretable machine learning method to retrieve key aerosol parameters from ground-based Sun-sky photometer measurements. Trained on simulated data covering diverse aerosol and atmospheric conditions, ensuring robustness and physical consistency. Applied to real observations, it agrees well with AERONET products and reduces computation time by orders of magnitude, offering a practical tool for monitoring aerosols and their effects on air quality and climate.
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