资源环境科技发展态势分析平台

The total effective radiative forcing (ERF) due to partial internally mixed (PIM) and externally mixed (EM) anthropogenic aerosols, as well as their climatic effects since the year of 1850, was evaluated and compared using the aerosol-climate online coupled model of BCC_AGCM2.0_CUACE/Aero. The influences of internal mixing (IM) on aerosol hygroscopicity parameter, optical properties, and concentration were considered. Generally, IM could markedly weaken the negative ERF and cooling effects of anthropogenic aerosols. The global annual mean ERF of EM anthropogenic aerosols from 1850 to 2010 was -1.87 W m(-2), of which the aerosol-radiation interactive ERF (ERFari) and aerosol-cloud interactive ERF (ERFaci) were -0.49 and -1.38 W m(-2), respectively. The global annual mean ERF due to PIM anthropogenic aerosols from 1850 to 2010 was -1.23 W m(-2), with ERFari and ERFaci of -0.23 and -1.01 W m(-2), respectively. The global annual mean surface temperature and water evaporation and precipitation were reduced by 1.74 K and 0.14 mm d(-1) for EM scheme and 1.28 K and 0.11 mm d(-1) for PIM scheme, respectively. However, the relative humidity near the surface was slightly increased for both mixing cases. The Intertropical Convergence Zone was southwardly shifted for both EM and PIM cases but was less southwardly shifted in PIM scheme due to the less reduction in atmospheric temperature in the midlatitude and low latitude of the Northern Hemisphere.

Plain Language Summary The internal mixing of aerosols is common in atmosphere. Different aerosol species merged together and become inhomogeneous particles with complex interior structures. Compared to the individual pure particles of external mixing, the treatment of internal mixing is much more complex and can bring about large changes in the optical and hygroscopic properties to the aerosol particles. In this paper, we discussed the impacts of anthropogenic aerosol mixing state on effective radiative forcing and some major climate factors since preindustrial era by introducing two mixing schemes of external mixing and partial internal mixing (PIM) to the BCC's Atmospheric General Circulation Model (BCC_AGCM2.0_CUACE/Aero). The results show that the cooling effect of anthropogenic aerosols is greatly reduced, the southward shift of ITCZ is alleviated, and the Hadley circulation is further inhibited due to PIM. However, to obtain the mixing properties (volume ratio, mixing rate, and material composition) of aerosols in a global scale is very difficult. The quantitative evaluation of aerosol internal mixing is still of large uncertainty.