Abstract
In this paper, based on the principle of Mie scattering, we calculated the optical parameters of BC aerosols at different scales and then applied the new optical parameters to simulate the BC aerosols concentration distribution, radiative forcing, and their climate effects. We also compared the results of optical parameters of BC aerosols with homogeneous scales and analyzed the effect on climate. Compared with the conventional uniform-scheme optical parameterization, the concentrations of the first mode of BC aerosols simulated with the optical parameters that were recalculated based on the particle size are significantly higher, while the concentrations of the other modes and the total of BC aerosols are lower. In the respective of statistics, the changes of column burdens of BC in four modes are 0.085, −0.095, −0.089, −0.054 mg/m2. The clear-sky TRF of BC are weakened in the value of 0.03 W/m2 averaged over the domain, while the all-sky TRF of BC are enhanced of 0.06 W/m2 in general. The warming effect of BC becomes weaker when using the new scheme by −0.04 K to −0.24 K. When using the new optical parameters scheme, the regional average surface concentrations of BC in four modes are 0.372, 0.264, 0.055 and 0.004 μg/m3, respectively. Especially, the first and the second mode account for as large as 53% and 38%. The surface concentration and column burden of total BC are 0.69 μg/m3 and 0.28 mg/m2 can be dropped. The regional average direct RFs of BC at the top of the atmosphere are 0.49 W/m2 under clear-sky and 0.36 W/m2 under all-sky averaged over the domain. Over most areas of central China, North China, and East China, BC may increase the temperature in a range of 0.05∼0.15 K, while over South China, BC shows cooling effect. In average, the precipitation variations caused by BC over East China, North China, South China, and Northeast China are −0.83, −0.05, −0.11, and −0.13 mm/d, respectively. As a whole, the variations of circulation, pressure, and temperature show a good correspondence.
Highlights
Atmospheric aerosols can affect the earth’s climate through both direct and indirect effects and play important roles in atmospheric radiation and climate change
E ground surface concentrations of the other modes of black carbon (BC) aerosols are lower under Scheme 2. e total ground surface concentrations of BC aerosols are lower under Scheme 2, and the range of differences is −0.2 to −2.8 μg/m3. e differences in the regional average concentrations of the four modes of BC aerosols and in the total BC aerosol ground surface concentrations are 0.24, −0.16, −0.18, −0.10, and −0.21 μg/m3, respectively
In the North China Plain and South China, the top-of-atmosphere radiative forcing (TRF) changes by −0.2 to −0.8 W/m2; near the Sichuan Basin, there is a region of strongly negative variations of TRF with a maximum value of −0.94 W/m2, which is consistent with the variations in the BC aerosol optical depth
Summary
Atmospheric aerosols can affect the earth’s climate through both direct and indirect effects and play important roles in atmospheric radiation and climate change. Among all of the anthropogenic aerosols, black carbon (BC) aerosols can effectively absorb solar radiation in the visible and infrared bands to heat the atmosphere and affect the climate and air quality [1, 2] and play a unique and important role in the climate systems. East Asia is an important source region of global aerosol emissions [5]. E anthropogenic aerosols in East Asia have increased, which has had a nonnegligible influence on the regional climate.
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