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首页> 外文期刊>Journal of Geophysical Research, D. Atmospheres: JGR >A global survey of the effect of cloud contamination on the aerosol optical thickness and its long-term trend derived from operational AVHRR satellite observations
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A global survey of the effect of cloud contamination on the aerosol optical thickness and its long-term trend derived from operational AVHRR satellite observations

机译：全球污染调查对云雾气溶胶光学厚度的影响及其长期趋势，这是根据实际的AVHRR卫星观测得出的

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Subpixel cloud contamination is one of the major issues plaguing passive satellite aerosol remote sensing. Its impact on the aerosol optical thickness (AOT) retrieval has been analyzed/evaluated by many studies. However, the question of how it influences the AOT trend remains to be answered. In this paper, four long-term advanced very high resolution radiometer (AVHRR) AOT data sets from 1981 to 2009 over global oceans for four different definitions of clear sky, respectively, are produced by applying a two-channel aerosol retrieval algorithm to the AVHRR clear-sky reflectances derived by combining NOAA Pathfinder Atmosphere's Extended AVHRR climate data record level-2b all-sky reflectances with the cloud probability parameter determined from the Bayesian probabilistic cloud detection technique. A global analysis of the effect of cloud contamination on the AVHRR AOT retrieval as well as on its long-term trend is then performed by comparing the results from the four data sets. It was found that cloud contamination imposes not only a positive bias on AOT values but also a positive bias on its long-term trend such that negative trends become less negative and positive trends become more positive. A cloud probability value of ≤1% has been identified as an optimal criterion for clear-sky definition to minimize the cloud contamination in the AVHRR aerosol retrieval while still retaining strong aerosol signals. In order for a satellite aerosol product to be useful and reliable in aerosol trend detection, the cloud contamination effect on aerosol trends needs to be studied/evaluated carefully along with the effects of calibration error, surface disturbance, and aerosol model assumptions.
机译：亚像素云污染是困扰无源卫星气溶胶遥感的主要问题之一。许多研究已经分析/评估了其对气溶胶光学厚度（AOT）取回的影响。但是，它如何影响AOT趋势的问题仍有待解决。本文通过将两通道气溶胶检索算法应用于AVHRR，分别产生了四种不同定义的晴空的1981年至2009年全球海洋上的四个长期高级超高分辨率辐射计（AVHRR）AOT数据集。通过将NOAA Pathfinder Atmosphere的扩展AVHRR气候数据记录2b级全天反射率与从贝叶斯概率云检测技术确定的云概率参数相结合得出的晴空反射率。然后，通过比较四个数据集的结果，对云污染对AVHRR AOT检索及其长期趋势的影响进行全局分析。人们发现，云污染不仅对AOT值产生正偏，而且对其长期趋势也产生正偏，从而使负趋势变少，负趋势变正。已确定≤1％的云概率值是晴空定义的最佳标准，以最大程度地减少AVHRR气溶胶回收中的云污染，同时仍保留强气溶胶信号。为了使卫星气溶胶产品在气溶胶趋势检测中有用且可靠，需要仔细研究/评估云对气溶胶趋势的污染以及校准误差，表面扰动和气溶胶模型假设的影响。

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