The polarized sun and sky radiometer SSARA: design, calibration, and application for ground based aerosol remote sensing
The polarized sun and sky radiometer SSARA: design, calibration, and application for ground based aerosol remote sensing
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DOI：
10.5194/amt-2019-226
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发表时间：
2019
影响因子：
2.3
通讯作者：
H. Grob;C. Emde;M. Wiegner;M. Seefeldner;B. Mayer
中科院分区：
文献类型：
--
作者：
H. Grob;C. Emde;M. Wiegner;M. Seefeldner;B. Mayer
抽象的。最近，偏振测定法已被用来增强经典光度测定法，以推断气溶胶的光学特性，因为偏振辐射包含有关颗粒的附加信息。因此，我们为 SSARA 太阳和天空光度计配备了偏振滤光片，用于测量 501.5 nm 的线偏振光。我们开发了一种新颖的辐射和偏振校准方法，使我们能够同时高精度地确定线性偏振器的衰减和相对方向（分别为 0.002 和 0.1°）。此外，我们采用了一种新的方位角安装校准方法，能够将仪器的指向校正到 32 弧分以内。到目前为止，这受到太阳跟踪器精度的限制。这两种方法都适用于其他太阳和天空辐射计，例如 AERONET 中使用的 Cimel CE318-DP 仪器。在 2017 年 4 月的 A-LIFE 实地活动期间，SSARA 收集了 22 天的数据。在这里，我们提出两个案例研究：第一个案例展示了在部分多云条件下从 SSARA 观测中反演气溶胶的性能。在另一种情况下，在完美的晴朗天空条件下，由于撒哈拉尘埃层而存在高气溶胶负荷。
Abstract. Recently, polarimetry has been used to enhance classical photometry to infer aerosol optical properties, as polarized radiation contains additional information about the particles. Therefore, we have equipped the SSARA sun and sky photometer with polarizer filters to measure linearly polarized light at 501.5 nm. We have developed a novel radiometric and polarimetric calibration method, which allows us to simultaneously determine the linear polarizers' diattenuation and relative orientation with high accuracy (0.002 and 0.1°, respectively). Furthermore, we employed a new calibration method for the azimuthal mount capable of correcting the instrument's pointing to within 32 arcmin. So far, this is limited by the accuracy of the sun-tracker. Both these methods are applicable to other sun and sky radiometers, such as Cimel CE318-DP instruments used in AERONET. During the A-LIFE field campaign in April 2017, SSARA collected 22 days of data. Here, we present two case studies: The first demonstrates the performance of an aerosol retrieval from SSARA observations under partially cloudy conditions. In the other case, a high aerosol load due to a Saharan dust layer was present during otherwise perfect clear sky conditions.