RUI: Spectral Imaging of Overcast Skies

这项研究的科学目的是利用最新的光谱成像技术来量化和更好地了解阴云的可见特征。这些改进将为检验阴云可见波长光谱结构的大气辐射传输模型的真实性创造新的观测标准。这项拟议研究的智力价值在于，它将以一种全新的方式研究阴云，通过从数字图像中提取高分辨率光谱来补充传统的光谱辐射测定法。这种组合允许对阴云经常快速变化的特征进行新的分析。在此之前，对阴天辐射光谱的精细角度细节进行研究是不可能的（当然也不可能逐秒进行），因此提出的研究构成了一种全新的大气被动遥感方法。没有类似的工作存在于狭窄视野的阴天辐射。阴天辐射度的光谱结构有助于描述云光学深度和吸收率的空间分布。这反过来又提供了对近地表热收支细节的见解。有了合适的数据反演技术，各种大气散射模型将被测试，看看它们在多大程度上解释了一个给定的阴天的可见结构，包括通过线性偏振器看到的细节。目前，似乎还没有关于阴天极化的详细观测研究。这种广泛的观察可以为日常现象提供有价值的新见解，这些现象现在被认为在理论和现象学上都得到了很好的理解。这项研究的更广泛影响将来自于对科学教育的好处和对公众的影响。为美国国家科学基金会资助的研究开发的数字成像技术将转化为日常课堂教学和海军学院学员为期一年的荣誉研究项目。提高对阴天辐射的空间和光谱分布的理解在从室内照明、公路安全到植物生长发育的许多领域都有实际应用。首席研究员的演讲很容易成为招募未来大气科学家的有力工具，也可以向公众推广。

The scientific objective of this research is to use newly available spectral imaging techniques to quantify and thus better understand overcasts' visible features. Such improvements will create new observational criteria for testing the realism of atmospheric radiative transfer models of overcasts' visible-wavelength spectral structure.The intellectual merit of the proposed research is that it would investigate overcasts in a fundamentally new way by complementing conventional spectroradiometry with high-resolution spectra extracted from digital images. This combination permits new kinds of analyses of overcasts' often rapidly changing features. Before now, studying the fine angular details of overcast radiance spectra has not been possible (and certainly not second-by-second), so the proposed research constitutes a wholly new method of atmospheric passive remote sensing. No comparable work exists for narrow field-of-view overcast radiances. The spectral structure of overcast radiances is useful in describing the spatial distribution of cloud optical depth and absorptivity. This in turn offers insights into details of the near-surface heat budget.With suitable data inversion techniques, various atmospheric scattering models will be tested to see how well they account for a given overcast's visible structure, including details seen through linear polarizers. Currently, no detailed observational study of overcast polarization seems to exist. Such wide-ranging observations can provide valuable new insights into everyday phenomena that are now thought to be well understood both theoretically and phenomenologically.The broader impacts of the study will be derived from benefits to science education and impacts on the general public. The digital imaging techniques developed for NSF-sponsored research will be translated into both daily classroom instruction and yearlong honors research projects for Naval Academy midshipmen. An improved understanding of the spatial and spectral distribution of overcast radiances has practical applications in many areas ranging from interior lighting and highway safety to plant growth and development. The principal investigator's presentations are apt to be a powerful recruiting tool for future atmospheric scientists and also for outreach to the general public.