Both observations and recent model results reveal a significant organic component in stratospheric aerosols. However, intrinsic optical properties (i.e., complex refractive index) of this organic component and the mixing state of organic and ubiquitous sulfuric acid components are quite uncertain. We examine the effects of different complex refractive indices and particle mixing states on shortwave radiative forcing (RF) of stratospheric aerosols in northern midlatitudes. In the absence of large volcanic sulfur emissions, our calculations show that organic components may have substantial impacts on stratospheric aerosol optical depth (AOD). Compared to pure sulfuric acid/water aerosol, organic-containing aerosols could cause ±100% change in shortwave RF (for low AOD conditions) depending on the refractive index and mixing state. The range found here of shortwave RF results, for different scenarios of organic complex refractive index and mixing state, call for better understandings of chemical and transport processes determining aerosol optical properties in the stratosphere.

中文翻译：

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中纬度北部平流层气溶胶短波辐射强迫的成分依赖性

观测和最近的模型结果都揭示了平流层气溶胶中的重要有机成分。然而，这种有机组分的固有光学特性（即复折射率）以及有机和普遍存在的硫酸组分的混合状态是相当不确定的。我们研究了不同复折射率和粒子混合状态对中纬度北部平流层气溶胶短波辐射强迫 (RF) 的影响。在没有大量火山硫排放的情况下，我们的计算表明有机成分可能对平流层气溶胶光学深度 (AOD) 产生重大影响。与纯硫酸/水气溶胶相比，根据折射率和混合状态，含有机物的气溶胶可能导致短波 RF（低 AOD 条件）发生 ±100% 的变化。