Sensitivity of PARASOL multi-angle photopolarimetric aerosol retrievals to cloud contamination
Sensitivity of PARASOL multi-angle photopolarimetric aerosol retrievals to cloud contamination
复制标题
PARASOL 多角度光偏振气溶胶反演对云污染的敏感性
DOI：
10.5194/amt-8-1287-2015
复制
发表时间：
2014
影响因子：
3.8
通讯作者：
T. Röckmann
中科院分区：
文献类型：
--
作者：
F. A. Stap;O. Hasekamp;T. Röckmann
抽象的。卫星对气溶胶进行遥感的一个重要问题是需要进行充分的云层筛选。如果应用的云筛选不够严格，地面场景可能会出现剩余云层，这会对反演的气溶胶参数造成很大的误差。另一方面，如果云筛选程序过于严格，太多的晴空情况，特别是近云场景，会被错误地标记为多云。云污染的有害影响以及可在这些近云场景中研究的气溶胶云相互作用的重要性要求采用新的云筛选方法。多角度、多波长的光偏振测量具有区分(液体)云滴和气溶胶粒子散射的独特能力。本文研究了多角度光极化测量的气溶胶反演对云污染的敏感性，并评估了基于拟合优度准则对云污染场景进行本质过滤的能力。为此，气溶胶反演算法被应用于部分云层的大洋上空合成数据集以及无云屏蔽的大洋POLDER-3/COLASOL观测。结果表明，拟合度滤光片、粗模折射率滤光片(mrcorate>；1.335)和卷云滤光片能够很好地滤除云污染场景。与遮阳伞观测的先验云屏蔽数据集(使用MODIS/AQA云掩膜)中检索的参数相比，在该固有云过滤器的检索参数中没有发现偏差或更大的SD。此外，较少的气溶胶浓度较高的场景被误解为云污染。反演的气溶胶光学厚度、单次散射反照率和Angstrom指数与AERONET观测结果吻合较好。此外，合成反演给出了算法正确反演微物理气溶胶参数的能力的信心。
Abstract. An important problem in satellite remote sensing of aerosols is related to the need to perform an adequate cloud screening. If a cloud screening is applied that is not strict enough, the ground scene has the probability of residual cloud cover which causes large errors on the retrieved aerosol parameters. On the other hand, if the cloud-screening procedure is too strict, too many clear sky cases, especially near-cloud scenes, will falsely be flagged cloudy. The detrimental effects of cloud contamination as well as the importance of aerosol cloud interactions that can be studied in these near-cloud scenes call for new approaches to cloud screening. Multi-angle multi-wavelength photopolarimetric measurements have a unique capability to distinguish between scattering by (liquid) cloud droplets and aerosol particles. In this paper the sensitivity of aerosol retrievals from multi-angle photopolarimetric measurements to cloud contamination is investigated and the ability to intrinsically filter the cloud-contaminated scenes based on a goodness-of-fit criteria is evaluated. Hereto, an aerosol retrieval algorithm is applied to a partially clouded over-ocean synthetic data set as well as non-cloud-screened over-ocean POLDER-3/PARASOL observations. It is found that a goodness-of-fit filter, together with a filter on the coarse mode refractive index (mrcoarse > 1.335) and a cirrus screening, adequately rejects the cloud-contaminated scenes. No bias or larger SD are found in the retrieved parameters for this intrinsic cloud filter compared to the parameters retrieved in a priori cloud-screened data set (using MODIS/AQUA cloud masks) of PARASOL observations. Moreover, less high-aerosol load scenes are misinterpreted as cloud contaminated. The retrieved aerosol optical thickness, single scattering albedo and Angstrom exponent show good agreement with AERONET observations. Furthermore, the synthetic retrievals give confidence in the ability of the algorithm to correctly retrieve the micro-physical aerosol parameters.