A partial internal mixing (PIM) treatment of black carbon (BC), organic carbon (OC), and sulphate was examined, and the core-shell model was used to represent the internally mixed aerosols with BC as the core and sulphate or OC as the shell. The influences of PIM treatment on the effective radiative forcing due to aerosol-radiative interaction (ERFari) and global temperature were examined and compared to those of external mixing (EM) treatment using an aerosol-climate online coupled model of BCC_AGCM2.0_CUACE/Aero. Radiative forcing due to aerosol-radiation interaction (RFari) of the anthropogenic aerosols since the preindustrial era was -0.34 W m(-2) for EM and -0.23 W m(-2) for PIM, respectively. The global annual mean ERFari of anthropogenic aerosols since the preindustrial era was -0.42 W m(-2) for EM and -0.34 W m(-2) for PIM, respectively. The change in global annual mean surface temperature increased accordingly from -0.18K in the EM case to -0.125K in the PIM case. Well geographic consistence between the change in low-level cloud amount and the change in temperature can be found. The atmospheric temperature in the troposphere was markedly less reduced in the PIM case than in the EM case. The RFari/ERFari for 50% and 100% were -0.11/-0.07 and 0.13/0.14 W m(-2), respectively. RFari, ERFari, and surface temperature changed approximately linearly with the internal mixing proportion.

The morphology, mixing state and hematite content of polluted mineral dust are not well accounted in the optical models and this leads to uncertainty in the radiative forcing estimation. In the present study, based on the morphological and mineralogical characterisation of polluted dust, the three-sphere, two-sphere and two-spheroid model shapes are considered. The optical properties of the above model shapes are computed using Discrete Dipole Approximation code. The single scattering albedo, omega(0), was found to vary depending on hematite content (0-6%) and model shape. For the two-sphere BC-mineral dust system, hematite was found to be a dominating absorber compared to that of black carbon as the R-BC/R-dust decreases. The omega(0) of the polluted dust system is larger if polluted dust is considered as pure dust spheroid (with 4% hematite) while smaller value is observed for Q(ext). Among all the systems, the omega(0) of BCBCD (two BC spheres attached to one dust sphere) system showed the maximum departure (40 and 35% for polluted dust with 0 and 6% hematite, respectively) from that of pure dust spheroid with 0 and 6% hematite. For the Asian region (pollution-prone zone), the modelled polluted dust optics will help to trace the optical and radiative properties of dust.