气候变化领域集成服务门户(CCPortal): Remote sensing of angular scattering effect of aerosols in a North American megacity

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DOI	10.1016/j.rse.2020.111760
	Remote sensing of angular scattering effect of aerosols in a North American megacity
	Zeng Z.-C.; Xu F.; Natraj V.; Pongetti T.J.; Shia R.-L.; Zhang Q.; Sander S.P.; Yung Y.L.
发表日期	2020
ISSN	00344257
卷号	242
英文摘要	The angle-dependent scattering effect of aerosols in the atmosphere not only influences climate through radiative forcing effects but also impacts trace gas remote sensing by modifying the path of radiation through the atmosphere. The aerosol phase function, which characterizes the angular signature of scattering, has been continuously monitored from ground-based and space-borne observations. However, the range of scattering angles these instruments can sample is very limited. Here, we report multi-year measurements from a mountain-top remote sensing instrument: the California Laboratory for Atmospheric Remote Sensing Fourier Transform Spectrometer (CLARS-FTS), which overlooks the Los Angeles megacity. The observational geometries of CLARS-FTS provide a wide range of scattering angles, from about 20° (forward) to about 140° (backward), which is larger than the range provided by any existing aerosol remote sensing instrument. We then quantify the aerosol angular scattering effect using the O2 ratio, which is the ratio of retrieved O2 Slant Column Density (SCD) to geometric O2 SCD. The O2 ratio quantifies the light path modification due to aerosol scattering, with a value of 1 representing an aerosol-free scenario. The lower the O2 ratio value than 1, the stronger the aerosol loading. CLARS-FTS measurements are highly sensitive to the angular scattering effect of aerosols in the Los Angeles (LA) urban atmosphere, due to the long light path going through the boundary layer and the wide range of observational angles. The differences in aerosol scattering between different surface reflection points targeted by CLARS-FTS can be explained by differences in their angular scattering geometries. The correlation between measurements at different targets can be used to quantify the strength of the angular dependence of the aerosol phase function. Applying the correlation technique to CLARS-FTS measurements, we find that, from 2011 to 2018, there is no significant trend in the aerosol phase function in the LA megacity. Overall, this study provides a practical observing strategy for quantifying the angular dependence of aerosol scattering in urban atmospheres that could potentially contribute towards improved greenhouse gas remote sensing in megacities. © 2020 Elsevier Inc.
英文关键词	Aerosol scattering; Angular dependence; CLARS; Megacity; Urban remote sensing
语种	英语
scopus关键词	Aerosols; Atmospheric radiation; Boundary layers; Fourier transform infrared spectroscopy; Geometry; Greenhouse gases; Radiation effects; Remote sensing; Space optics; Spacecraft instruments; Aerosol scattering; Angular dependence; CLARS; Megacities; Urban remote sensing; Forward scattering; aerosol; instrumentation; megacity; radiative forcing; remote sensing; scattering; North America
来源期刊	Remote Sensing of Environment
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/179360
作者单位	JIFRESSE, University of California, Los Angeles, Los Angeles, United States; Division of Geological and Planetary Sciences, California Institute of Technology, United States; School of Meteorology, The University of Oklahoma, United States; Jet Propulsion Laboratory, California Institute of Technology, United States
推荐引用方式 GB/T 7714	Zeng Z.-C.,Xu F.,Natraj V.,et al. Remote sensing of angular scattering effect of aerosols in a North American megacity[J],2020,242.
APA	Zeng Z.-C..,Xu F..,Natraj V..,Pongetti T.J..,Shia R.-L..,...&Yung Y.L..(2020).Remote sensing of angular scattering effect of aerosols in a North American megacity.Remote Sensing of Environment,242.
MLA	Zeng Z.-C.,et al."Remote sensing of angular scattering effect of aerosols in a North American megacity".Remote Sensing of Environment 242(2020).