Abstract The impact of moderately absorbing aerosols on the energy budget over Central Europe is discussed, based on experimental observations and numerical simulations obtained for the summer of 2015. Aerosol events, defined as aerosol optical depth (AOD) at 500 nm greater than 0.15, especially in August, are mostly attributed to transport of biomass burning (BB) from Eastern Europe. Shortwave (SW) aerosol radiative forcings (ARF) at the surface and the top of the atmosphere (TOA) are estimated from ensembles of ten and eight observational and model-based approaches, respectively. Different measuring methods, including unmanned aviation system (UAS) and ground-based measurements, radiative transfer models, including MOTRAN and Fu-Liou, and parameterisations of aerosol optical properties regarding full vertical profiles, columnar and surface properties, are used in these approaches. The mean ARF is −15.9 ± 2.1 W/m2, -9.1 ± 1.4 W/m2, and 7.0 ± 1.0 W/m2, respectively, for the Earth's surface, TOA, and atmosphere under clear conditions for June–August 2015. During an aerosol event with AOD peak of about 0.6 at 500 nm, the daily mean surface, TOA, and atmosphere ARF are around −30, −18, and 13 W/m2, respectively. The mean ARF differences between all methods are about 4.0 W/m2 for the surface and about 2.3 W/m2 for the TOA, which correspond to 23% of ensemble means. Aerosols are also shown to have a significant impact on observed surface sensible and latent heat fluxes for the study period. Flux sensitivity to AOD for a solar zenith angle of 45° is −70 ± 41 W/m2/τ500, -112 ± 56 W/m2/τ500, and -119 ± 19 W/m2/τ500, respectively, for sensible, latent, and net SW and longwave (LW) radiation flux. When averaged over day time, sensitivities of sensible heat, latent heat fluxes, and net radiation fluxes to AOD are reduced by about 50%, 20%, and 70%, respectively.

中文翻译：

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2015年夏季中欧中等吸收气溶胶对地表感、潜和净辐射通量的影响

摘要 基于 2015 年夏季获得的实验观测和数值模拟，讨论了中等吸收气溶胶对中欧能量收支的影响。气溶胶事件，定义为 500 nm 处大于 0.15 的气溶胶光学深度 (AOD)，特别是在 8 月，主要归因于来自东欧的生物质燃烧 (BB) 的运输。地表和大气顶部 (TOA) 的短波 (SW) 气溶胶辐射强迫 (ARF) 分别通过 10 种和 8 种观测和模型方法的集合进行估计。不同的测量方法，包括无人驾驶航空系统 (UAS) 和地面测量，辐射传输模型，包括 MOTRAN 和 Fu-Liou，以及关于完整垂直剖面的气溶胶光学特性的参数化，在这些方法中使用柱状和表面属性。2015 年 6 月至 8 月在晴朗条件下，地球表面、TOA 和大气的平均 ARF 分别为 -15.9 ± 2.1 W/m2、-9.1 ± 1.4 W/m2 和 7.0 ± 1.0 W/m2。在 500 nm 处 AOD 峰值约为 0.6 的气溶胶事件，日平均表面、TOA 和大气 ARF 分别约为 -30、-18 和 13 W/m2。所有方法之间的平均 ARF 差异对于表面约为 4.0 W/m2，对于 TOA 约为 2.3 W/m2，对应于整体平均值的 23%。研究还表明，气溶胶对研究期间观察到的地表感热和潜热通量有显着影响。对于 45° 的太阳天顶角，对 AOD 的通量敏感度分别为 -70 ± 41 W/m2/τ500、-112 ± 56 W/m2/τ500 和 -119 ± 19 W/m2/τ500，对于敏感、潜在, 和净 SW 和长波 (LW) 辐射通量。当在白天平均时，显热、潜热通量和净辐射通量对 AOD 的敏感性分别降低了约 50%、20% 和 70%。