不同污染条件下气溶胶对短波辐射通量影响的模拟研究

Simulation of aerosol influences on shortwave radiative flux under different pollution conditions

中文关键词:  气溶胶  直接辐射强迫  辐射强迫效率  BCC_RAD

英文关键词:Aerosol  Direct radiative forcing  Radiative forcing efficiency  BCC_RAD

中文摘要:

      将高光谱分辨率的气溶胶光学参数化方案应用于高精度的辐射传输模式BCC_RAD（974带）中，研究不同污染状况下气溶胶在地表与近地层大气中造成的直接辐射强迫与辐射强迫效率。发现气溶胶在地表产生的直接辐射强迫为负，在近地层大气中产生的直接辐射强迫为正，且随气溶胶浓度的升高变大，说明大气气溶胶的含量越高，单位气溶胶光学厚度产生的直接辐射强迫越大。将短波划分为3个波段：紫外、可见光和近红外，发现在紫外、可见光和近红外波段中，不同污染状况下气溶胶在地表造成的直接辐射强迫范围分别为：-1.36—-13.66、-3.03—-32.41和-2.74—-28.62 W/m²，在近地层大气中产生的直接辐射强迫范围分别为0.44—4.26、0.99—9.80和0.93—8.87 W/m²。通过进一步对比自然和人为气溶胶的影响，发现人为气溶胶在地表和大气层顶产生的负直接辐射强迫以及对整层和近地面大气造成的正直接辐射强迫均大于自然气溶胶的影响，且上述两种排放源的气溶胶对整层大气辐射收支的影响主要集中在800 hPa高度以下的大气中。按照地表直接辐射强迫大小来分析不同种类气溶胶的影响，结果为硫酸盐 > 有机碳 > 黑碳 > 海盐 > 沙尘；按照近地层大气直接辐射强迫大小排序则为黑碳 > 有机碳 > 沙尘 > 海盐 > 硫酸盐。最后，通过分析散射型气溶胶与吸收型气溶胶对辐射通量的影响，还探究了大气中散射与吸收过程的异同。

英文摘要:

      Aerosol optical properties with high spectral resolution are applied in the radiative transfer model of BCC_RAD (974 bands) to simulate direct radiative forcing (DRF) and radiative forcing efficiency (DFE) of aerosols in the surface and near-surface layer under different pollution conditions. It is found that DRF is negative in the surface but positive in near-surface layer. The DFE increases with increasing aerosol concentration, indicating that higher concentration of atmospheric aerosols cause larger DRF with unit aerosol optical depth (AOD). The shortwave band (SW) is divided into three bands:ultraviolet (UV), visible (VIS) and near-infrared (NIR). The DRF ranges under different pollution conditions in these three bands are -1.36—-13.66, -3.03—-32.41 and -2.74—-28.62 W/m² at the surface, respectively, and the corresponding DRF ranges are 0.44-4.26, 0.99-9.80 and 0.93-8.87 W/m² in the near-surface layer, respectively.
The negative DRF at the surface (SUR) and in the top of the atmosphere (TOA) and the positive DRF over the entire atmospheric layer and at the near-surface caused by anthropogenic aerosols are greater than those caused by natural aerosols. The effects of aerosols from these two sources on the atmospheric radiation balance are mainly concentrated in the atmosphere higher than 800 hPa. The effects of different types of aerosols on radiation are then analyzed according to the magnitude of absolute value of the DRF. Results indicate that SF (sulfate) > OC (organic carbon) > BC (black carbon) > SS (sea salt) > SD (dust) at the surface, and BC > OC > SD > SS > SF in near-surface layer. Finally, the effects of scattering aerosol (SF) and absorbing aerosol (BC) on the radiative flux are analyzed, and the differences between the scattering and absorbing processes in the atmosphere are also compared.