Simultaneous retrieval of aerosol refractive index and particle size distribution from ground-based measurements of direct and scattered solar radiation.
Simultaneous retrieval of aerosol refractive index and particle size distribution from ground-based measurements of direct and scattered solar radiation.
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从直接和散射太阳辐射的地面测量中同时检索气溶胶折射率和粒径分布。
DOI：
10.1364/ao.38.007305
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发表时间：
1999
期刊：
影响因子：
1.9
通讯作者：
B. McArthur
中科院分区：
文献类型：
--
作者：
P. Romanov;N. O'Neill;A. Royer;B. McArthur
地面太阳光度计观测直接和散射太阳辐射是提供气溶胶光学特性数据的传统工具。光谱透射和太阳光环测量提供了气溶胶信息的光源，可以将其反演以检索微物理特性（粒径分布和折射率）。然而，为了从地面遥感测量推断这些气溶胶特性，应该开发和应用特殊的数值反演方法。我们对现有反演技术提出了两项改进，该技术用于从大气传输和太阳光环测量相结合得出气溶胶微物理特性。首先，气溶胶折射率直接包含在反演过程中，并与粒径谱同时检索。其次，我们通过将散射角误差的校正因子作为检索的反演参数来考虑真实或有效的仪器指向误差。该反演技术经过数值模拟验证并应用于现场数据。结果表明，地面太阳光度计测量能够得出气溶胶折射率的实部，绝对误差为 0.03-0.05，并粗略地区分弱吸收气溶胶和强吸收气溶胶。光环角度观测方案可以细化，绝对精度为0.15-0.19度。通常发现对散射角误差的偏移校正很小并且始终在 -0.17 的量级。推断该误差幅度主要是由于非线性视场平均效应而不是仪器误差造成的。
Ground-based sunphotometer observation of direct and scattered solar radiation is a traditional tool for providing data on aerosol optical properties. Spectral transmission and solar aureole measurements provide an optical source of aerosol information, which can be inverted for retrieval of microphysical properties (particle size distribution and refractive index). However, to infer these aerosol properties from ground-based remote-sensing measurements, special numerical inversion methods should be developed and applied. We propose two improvements to the existing inversion techniques employed to derive aerosol microphysical properties from combined atmospheric transmission and solar aureole measurements. First, the aerosol refractive index is directly included in the inversion procedure and is retrieved simultaneously with the particle size spectra. Second, we allow for real or effective instrumental pointing errors by including a correction factor for scattering angle errors as a retrieved inversion parameter. The inversion technique is validated by numerical simulations and applied to field data. It is shown that ground-based sunphotometer measurements enable one to derive the real part of the aerosol refractive index with an absolute error of 0.03-0.05 and to distinguish roughly between weakly and strongly absorbing aerosols. The aureole angular observation scheme can be refined with an absolute accuracy of 0.15-0.19 deg. Offset corrections to the scattering angle error are generally found to be small and consistently of the order of -0.17. This error magnitude is deduced to be due primarily to nonlinear field-of-view averaging effects rather than to instrumental errors.