气候变化领域集成服务门户(CCPortal): A global study of hygroscopicity-driven light-scattering enhancement in the context of other in situ aerosol optical properties

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DOI	10.5194/acp-21-13031-2021
	A global study of hygroscopicity-driven light-scattering enhancement in the context of other in situ aerosol optical properties
	Titos G.; Burgos M.A.; Zieger P.; Alados-Arboledas L.; Baltensperger U.; Jefferson A.; Sherman J.; Weingartner E.; Henzing B.; Luoma K.; O'Dowd C.; Wiedensohler A.; Andrews E.
发表日期	2021
ISSN	1680-7316
起始页码	13031
结束页码	13050
卷号	21 期号:17
英文摘要	The scattering and backscattering enhancement factors (f (RH) and fb(RH)) describe how aerosol particle light scattering and backscattering, respectively, change with relative humidity (RH). They are important parameters in estimating direct aerosol radiative forcing (DARF). In this study we use the dataset presented in Burgos et al. (2019) that compiles f (RH) and fb(RH) measurements at three wavelengths (i.e., 450, 550 and 700 nm) performed with tandem nephelometer systems at multiple sites around the world. We present an overview of f (RH) and fb(RH) based on both long-term and campaign observations from 23 sites representing a range of aerosol types. The scattering enhancement shows a strong variability from site to site, with no clear pattern with respect to the total scattering coefficient. In general, higher f (RH) is observed at Arctic and marine sites, while lower values are found at urban and desert sites, although a consistent pattern as a function of site type is not observed. The backscattering enhancement fb(RH) is consistently lower than f (RH) at all sites, with the difference between f (RH) and fb(RH) increasing for aerosol with higher f (RH). This is consistent with Mie theory, which predicts higher enhancement of the light scattering in the forward than in the backward direction as the particle takes up water. Our results show that the scattering enhancement is higher for PM1 than PM10 at most sites, which is also supported by theory due to the change in scattering efficiency with the size parameter that relates particle size and the wavelength of incident light. At marine-influenced sites this difference is enhanced when coarse particles (likely sea salt) predominate. For most sites, f (RH) is observed to increase with increasing wavelength, except at sites with a known dust influence where the spectral dependence of f (RH) is found to be low or even exhibit the opposite pattern. The impact of RH on aerosol properties used to calculate radiative forcing (e.g., single-scattering albedo, w0, and backscattered fraction, b) is evaluated. The single-scattering albedo generally increases with RH, while b decreases. The net effect of aerosol hygroscopicity on radiative forcing efficiency (RFE) is an increase in the absolute forcing effect (negative sign) by a factor of up to 4 at RH D 90 % compared to dry conditions (RH < 40 %). Because of the scarcity of scattering enhancement measurements, an attempt was made to use other more commonly available aerosol parameters (i.e., w0 and scattering Ångström exponent, asp) to parameterize f (RH). The majority of sites (75 %) showed a consistent trend with w0 (higher f (RH D 85 %) for higher w0), while no clear pattern was observed between f (RH D 85 %) and asp. This suggests that aerosol w0 is more promising than asp as a surrogate for the scattering enhancement factor, although neither parameter is ideal. Nonetheless, the qualitative relationship observed between w0 and f (RH) could serve as a constraint on global model simulations. © 2021 The Author(s).
语种	英语
scopus关键词	aerosol property; backscatter; hygroscopicity; light scattering; optical property; radiative forcing; relative humidity
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/246615
作者单位	Andalusian Institute for Earth System Research, University of Granada, Granada, 18006, Spain; Department of Applied Physics, University of Granada, Granada, 18071, Spain; Department of Environmental Science, Stockholm University, Stockholm, Sweden; Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden; Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland; Cooperative Institute for Research in Environmental Studies, University of Colorado, Boulder, CO 80309, United States; Department of Physics and Astronomy, Appalachian State University, Boone, NC, United States; Netherlands Organisation for Applied Scientific Research (TNO), Princetonlaan 6, Utrecht, 3584, Netherlands; Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, P.O. Box 68, Helsinki, 00014, Finland; School of Physics, Ryan Institute's Centre for Climate and Air Pollution Studies, National University of Ireland Galway, University Road, Galway...
推荐引用方式 GB/T 7714	Titos G.,Burgos M.A.,Zieger P.,et al. A global study of hygroscopicity-driven light-scattering enhancement in the context of other in situ aerosol optical properties[J],2021,21(17).
APA	Titos G..,Burgos M.A..,Zieger P..,Alados-Arboledas L..,Baltensperger U..,...&Andrews E..(2021).A global study of hygroscopicity-driven light-scattering enhancement in the context of other in situ aerosol optical properties.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(17).
MLA	Titos G.,et al."A global study of hygroscopicity-driven light-scattering enhancement in the context of other in situ aerosol optical properties".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.17(2021).