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The AI-based Nonspherical Aerosol Optical Scheme (AI-NAOS) is a newly developed aerosol optical module that improves the representation of aerosol optical properties for radiative transfer simulations in atmospheric models. It incorporates the nonsphericity and inhomogeneity (NSIH) of internally mixed aerosol particles through a deep learning method. Specifically, the AI-NAOS considers black carbon (BC) as fractal aggregates and models soil dust (SD) as super-spheroids, encapsulated partially or completely with hygroscopic aerosols such as sulfate, nitrate, and aerosol water. To obtain AI-NAOS, a database of the optical properties for the models was constructed using the invariant imbedding T-matrix method (IITM), and deep neural networks (DNN) were trained based on this database. In this study, the AI-NAOS was integrated into the mesoscale version 5.1 of Global/Regional Assimilation and Prediction System with Chinese Unified Atmospheric Chemistry Environment (GRAPES_Meso5.1/CUACE). Real-case simulations were conducted during a winter with high pollution, comparing BC aerosols evaluated using three schemes with spherical aerosol models (external-mixing, core-shell, and volume-mixing) and the AI-NAOS scheme. The results showed that NSIH effect led to a moderate estimation of absorbing aerosol optical depth (AAOD) and obvious changes in aerosol radiative effects, short-wave heating rates, temperature profiles, and boundary layer height. The AAOD values based on three spherical schemes were 70.4 %, 125.3 %, and 129.3 % over Sichuan Basin, benchmarked to the AI-NAOS results. Compared to the external-mixing scheme, the direct radiative effect (DRE) induced by the NSIH effect reached +1.6 W/m2 at the top-of-atmosphere (TOA) and -2.9 W/m2 at surface. The NSIH effect could enhance the short-wave heating rate, reaching 20 %. Thus, the warming effect at 700 hPa and the cooling effect on the ground were strengthened by 21 % and 13 %, reaching +0.04 and –0.10 K, which led to a reduction in the height of the Planetary Boundary Layer (PBL) by –11 meters. In addition, the precipitation was inhibited by the NSIH effect, causing a 15 % further decrease. Therefore, the NSIH effects demonstrated their non-negligible impacts and highlighted the importance of incorporating them into chemical weather models. [ABSTRACT FROM AUTHOR]

• A new internally-mixed aerosol optics scheme was developed. • Artificial neural networks were used to parameterize aerosol optical properties. • The inhomogeneous aerosol model had lower absorption than the well-mixed model. • The optics scheme was evaluated using the Weather Research and Forecasting model. • The impact of particle inhomogeneity was obvious in the planetary boundary layer. A new internally-mixed aerosol optics scheme was developed. Aerosols (organic carbon, sea salt, aerosol water, sulfate, and nitrate) were assumed to be internally mixed with black carbon and soil dust (BC and SD, respectively), both of which are treated as cores. In the SD-containing particles, the particle non-sphericity was incorporated. Aerosol optical properties were computed from the invariant imbedding T-matrix method and the Lorenz–Mie theory and then parameterized using a novel method involving artificial neural networks (ANN). The new scheme was evaluated using the Weather Research and Forecasting (WRF) model. A case study involving East Asia was performed on Dec 3-4, 2010. Compared to uniformly mixed aerosols, inhomogeneous mixed aerosols had lower absorbability and stronger solar backscattering, causing a positive aerosol direct radiative effect (DRE) bias at the surface (3.0 and 2.6 W/m2 for the Sichuan Basin and Northern China, respectively) and negative DRE bias at the top of atmosphere ([TOA], −3.5 and −2.2 W/m2, respectively). Inhomogeneity effects caused a large reduction (up to 0.2K) in the atmospheric warming above the planetary boundary layer (PBL) and caused a northerly anomaly at 850 hPa on the order of 0.3 m/s. The non-sphericity effect was only significant over the Tarim Basin. DREs related to non-sphericity decreased at both the surface and TOA (−1.0 and −0.6 W/m2, respectively) due to stronger extinction. Non-sphericity caused more surface dimming and more solar heating, which had opposite effects on temperature perturbation, producing a more obvious impact within the PBL than in the free atmosphere. [ABSTRACT FROM AUTHOR]