Dust Aerosols Enhance China's Gross Primary Productivity by Increasing Diffuse Radiation

Dust aerosols play a crucial role in Earth's biogeochemical processes by modulating solar radiation and affecting terrestrial ecosystem productivity. In China, extensive arid and semi-arid regions contribute to high dust aerosol emissions, yet the long-term impact of dust aerosols on gross primary productivity (GPP) remains insufficiently quantified. This study coupled the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) and the Joint UK Land Environment Simulator (JULES) to quantify the impact of dust aerosol radiative forcing on GPP in China's terrestrial ecosystems from 2000 to 2020. Results indicated that dust aerosols significantly alter surface solar radiation components by reducing direct radiation and enhancing diffuse radiation. The mean annual decrease in direct radiation due to dust aerosols was −8.2 ± 0.2 W m⁻², while the increase in diffuse radiation was 5.3 ± 0.1 W m⁻², leading to a net reduction in total surface solar radiation of around −2.9 W m⁻². These radiative changes resulted in an average annual increase in GPP of approximately 0.11 ± 0.024 Pg C yr⁻¹, accounting for around 2% of China's mean annual GPP of 6.44 ± 0.18 Pg C yr⁻¹ during the study period. The enhancement was particularly pronounced in regions with high dust aerosol loads, such as northwest China, and exhibited notable interannual variability. This study underscores the complex interactions between dust aerosols and terrestrial ecosystems, highlighting the importance of considering aerosol radiative effects in carbon cycle assessments and climate models.