Sensitivity of multiangle imaging to aerosol optical depth and to pure-particle size distribution and composition over ocean
Sensitivity of multiangle imaging to aerosol optical depth and to pure-particle size distribution and composition over ocean
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DOI：
10.1029/98jd01752
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发表时间：
1998-12-27
影响因子：
4.4
通讯作者：
Diner, DJ
中科院分区：
文献类型：
--
作者：
Kahn, R;Banerjee, P;Diner, DJ
多角度、多光谱遥感观测，如预期由地球观测系统（EOS）多角度成像光谱仪（MISR）进行的观测，可以显著提高我们从空间约束气溶胶特性的能力。在无云、平静的海洋条件下，对具有自然光学深度、粒径和折射率范围的纯粒子进行了模拟研究。根据理论模拟，我们可以从平静的海洋上测量出除最暗的颗粒外的所有柱光学深度，这些颗粒具有典型的尺寸分布和组成，不确定性最多为0.05或20%，取较大的值，即使颗粒性质鲜为人知。对于一种常见的颗粒类型，烟灰，在黑暗海洋上对光学深度的限制非常差。模拟测量还使我们能够区分球形和非球形颗粒，根据折射率区分两到四个组成组，并在大多数纬度上识别出0.1到2.0 μ m特征半径范围内的三到四个不同的尺寸组。该技术对“积累模式”尺寸下的粒子微物理特性最为敏感，在MISR波长下，粒子散射经历了从瑞利模式到大粒子模式的转变。在这些结果的基础上，我们期望利用多角度遥感数据，在常规和全球范围内区分含有不同气溶胶类型的气团。这些数据补充了现场和现场数据，可以提供有关当地气溶胶大小和成分的详细信息。将这项研究扩展到纯粒子的混合物是继续工作的一部分。
Multiangle, multispectral remote sensing observations, such as those anticipated from the Earth Observing System (EOS) Multiangle Imaging Spectroradiometer (MISR), can significantly improve our ability to constrain aerosol properties from space. Simulations over cloud-free, calm ocean conditions were studied for pure particles with natural ranges of optical depth, particle size, and indices of refraction. According to the theoretical simulations we can retrieve column optical depth from measurements over calm ocean for all but the darkest particles, with typical size distributions and compositions, to an uncertainty of at most 0.05 or 20%, whichever is larger, even if the particle properties are poorly known. For one common particle type, soot, constraints on the optical depth over dark ocean are very poor. The simulated measurements also allow us to distinguish spherical from nonspherical particles, to separate two to four compositional groups based on indices of refraction, and to identify three to four distinct size groups between 0.1 and 2.0 mu m characteristic radius at most latitudes. The technique is most sensitive to particle microphysical properties in the "accumulation mode" sizes, where particle scattering undergoes the transition from Rayleigh to large-particle regimes for the MISR wavelengths. On the basis of these results we expect to distinguish air masses containing different aerosol types, routinely and globally, with multiangle remote sensing data. Such data complement in situ and field data, which can provide detailed information about aerosol size and composition locally. An extension of this study to mixtures of pure particles is part of continuing work.