Aerosol hygroscopicity is a critical parameter for predicting radiative forcing and climate sensitivity, particularly under sub-saturated regimes where it drives complex aerosol–water interactions. Here, we show that externally mixed aerosols exert a stronger influence on direct radiative forcing than is currently represented in models. Incorporating our findings into radiative forcing calculations indicates a stronger aerosol cooling effect, especially at suburban sites, highlighting the importance of representing regional differences in mixing state. The conventional bulk-chemistry approach, which assumes volume-based mixing with limited spatial variability, exhibits low predictive performance for aerosol hygroscopicity (R² ≈ 0.61) at urban and suburban sites. Using an interpretable machine learning framework trained on geographically diverse, region-specific datasets can capture this variability with higher accuracy (R² ≈ 0.97), identifying key chemical compositional and mixing-state drivers.
Incorporating regional diversity of aerosol hygroscopicity provides a more accurate representation of aerosol hygroscopicity in climate models, according to a machine learning approach trained on aerosol observational data.
- Regional aerosol hygroscopicity influences radiative forcing globally
- Shravan Deshmukh - Leibniz Institute for Tropospheric ResearchPau Ferrer-Cid - Universitat Politècnica de CatalunyaBaseerat Romshoo - Leibniz Institute for Tropospheric ResearchLaurent Poulain - Leibniz Institute for Tropospheric ResearchJose M. Barcelo-Ordinas - Universitat Politècnica de CatalunyaJorge Garcia-Vidal - Universitat Politècnica de CatalunyaAliki Christodoulou - Paul Scherrer InstituteSpyros Bezantakos - Cyprus InstituteCyrielle Denjean - Météo-FranceBarbara D’Anna - Aix-Marseille UniversitéPaola Formenti - Paris-Est SupSubrata Mukherjee - Indian Institute of Tropical MeteorologyGazala Habib - Indian Institute for Technology New Delhi (IIT-D)Prashant Kumar - Global Centre for Clean Air Research (GCARE), School of Engineering, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Institute for Sustainability, University of Surrey, GuildfordShan Huang - College of Environment and ClimateZhijun Wu - State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and EngineeringBirgit Wehner - Leibniz Institute for Tropospheric ResearchSilvia Henning - Leibniz Institute for Tropospheric ResearchMar Viana - Institute of Environmental Assessment and Water ResearchMarkus D. Petters - University of California, RiversideAjit Ahlawat - Delft University of TechnologyMira Pöhlker - Leipzig University
- Communications earth & environment, Vol.7(1), p.416
- Nature Publishing Group UK
- 07/05/2026
- WE 2757/4-1 / Deutsche Forschungsgemeinschaft (German Research Foundation) (https://doi.org/10.13039/501100001659)
- 991128206802346
- Mechanical Engineering Sciences
- English
- Journal article