Geoengineering: Whiter skies?
Geoengineering: Whiter skies?
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地球工程：天空更白？
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
K. Caldeira
中科院分区：
文献类型：
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作者：
B. Kravitz;D. MacMartin;K. Caldeira
使用平流层硫酸盐气溶胶的地球工程的一个拟议副作用是白天天空变白，日落时产生余辉，就像大规模火山喷发后所看到的那样。平流层中的硫酸盐气溶胶会增加地面接收的漫射光，但光谱分布不均匀。我们使用一个辐射传输模型来计算理想的硫酸盐气溶胶尺寸分布的光谱辐照度。总辐照度减少2%，大约足以抵消二氧化碳浓度翻倍造成的人为升温，天空变亮(漫射光增加)3至5倍，具体取决于气溶胶的大小分布。当光学薄卷云被包括在我们的模拟中时，相对增加较少。半径较小的粒子对光谱形状的影响很小。半径为∼0.5μm的颗粒优先增加红色波长的漫射辐照度，而大颗粒(∼0.9μm)优先增加蓝色波长的漫射辐照度。光谱显示主要波长几乎没有变化，这表明天空色调几乎没有变化，但所有颗粒尺寸分布都会产生相对于晴朗天空条件下的白光增加。我们在平流层气溶胶地球工程模拟中的漫射天空光谱与今天城市地区的平均条件相似。
One proposed side effect of geoengineering with stratospheric sulfate aerosols is sky whitening during the day and afterglows near sunset, as is seen after large volcanic eruptions. Sulfate aerosols in the stratosphere would increase diffuse light received at the surface, but with a non‐uniform spectral distribution. We use a radiative transfer model to calculate spectral irradiance for idealized size distributions of sulfate aerosols. A 2% reduction in total irradiance, approximately enough to offset anthropogenic warming for a doubling of CO2 concentrations, brightens the sky (increase in diffuse light) by 3 to 5 times, depending on the aerosol size distribution. The relative increase is less when optically thin cirrus clouds are included in our simulations. Particles with small radii have little influence on the shape of the spectra. Particles of radius ∼0.5 μm preferentially increase diffuse irradiance in red wavelengths, whereas large particles (∼0.9 μm) preferentially increase diffuse irradiance in blue wavelengths. Spectra show little change in dominant wavelength, indicating little change in sky hue, but all particle size distributions produce an increase in white light relative to clear sky conditions. Diffuse sky spectra in our simulations of geoengineering with stratospheric aerosols are similar to those of average conditions in urban areas today.