Observation‐Based Study on Aerosol Optical Depth and Particle Size in Partly Cloudy Regions
Observation‐Based Study on Aerosol Optical Depth and Particle Size in Partly Cloudy Regions
复制标题
部分多云地区气溶胶光学深度和粒径的观测研究
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
T. Eck
中科院分区：
文献类型：
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作者：
T. Várnai;T. Várnai;A. Marshak;T. Eck;T. Eck
这项研究旨在通过使用卫星数据检查气溶胶特性与附近低空云量之间的统计关系来帮助更好地了解气溶胶-云相互作用。中分辨率成像光谱仪观测的全球数据集的分析表明，云量和气溶胶光学厚度（AOD）之间的正相关关系在早期的研究报告是强大的整个地球仪和在冬季和夏季。通常情况下，在多云的日子里，AOD比多云的日子高出30-50%。结合卫星观测和现代研究与应用回顾分析，第2版全球再分析数据显示，对于所有考虑的气溶胶类型：硫酸盐，尘埃，碳和海盐，云量和AOD之间的相关性很强。观测结果还表明，在附近有云的情况下，气溶胶粒径分布往往会在地球的大面积区域内向较小的颗粒转移。这与细模式的AOD比粗模式粒子的AOD更大的云相关增加一致。精细模式AOD的较大增加意味着云量-AOD相关性并不主要来自云检测的不确定性。此外，结果表明，气溶胶粒子的大小增加云附近，即使在地区，它随着云量增加而减少。这表明云量的减少主要来自大尺度环境的变化，而不是云增加了精细模式气溶胶的数量或大小。最后，结合不同的气溶胶反演算法表明，质量评估标志的基础上，当地的变化，可以帮助确定所观察到的气溶胶种群受到周围的云。
This study seeks to help better understand aerosol‐cloud interactions by examining statistical relationships between aerosol properties and nearby low‐altitude cloudiness using satellite data. The analysis of a global data set of Moderate Resolution Imaging Spectroradiometer observations reveals that the positive correlation between cloudiness and aerosol optical depth (AOD) reported in earlier studies is strong throughout the globe and during both winter and summer. Typically, AOD is 30–50% higher on cloudier‐than‐average days than on less cloudy days. A combination of satellite observations and Modern‐Era Retrospective analysis for Research and Applications, Version 2 global reanalysis data reveals that the correlation between cloud cover and AOD is strong for all aerosol types considered: sulfate, dust, carbon, and sea salt. The observations also indicate that in the presence of nearby clouds, aerosol size distributions tend to shift toward smaller particles over large regions of the Earth. This is consistent with a greater cloud‐related increase in the AOD of fine‐mode than of coarse‐mode particles. The greater increase in fine‐mode AOD implies that the cloudiness‐AOD correlation does not come predominantly from cloud detection uncertainties. Additionally, the results show that aerosol particle size increases near clouds even in regions where it decreases with increasing cloudiness. This suggests that the decrease with cloudiness comes mainly from changes in large‐scale environment, rather than from clouds increasing the number or the size of fine‐mode aerosols. Finally, combining different aerosol retrieval algorithms demonstrated that quality assessment flags based on local variability can help identifying when the observed aerosol populations are affected by surrounding clouds.