Effects of relative humidity on aerosol light scattering: results from different European sites

Zieger, Paul; Fierz-Schmidhauser, R.; Weingärtner, E.; Baltensperger, Urs

doi:10.5194/acp-13-10609-2013

Cited by 207 publications

(209 citation statements)

References 62 publications

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“…The average modeled enhancement factor f (RH = 85 %) during the campaign period was 4.03 ± 0.50 (mean ± standard deviation), which is higher than 3.24 ± 0.63 reported in Zieger et al (2010). One possible reason for this could be an overestimation of the apparent hygroscopicity (i.e., sea salt only attributed to the fine mode below 790 nm) leading to an overestimation of the resulting f (RH) (see also Zieger et al, 2013). Another reason for this bias could be the different dry scattering coefficient data used in the studies.…”

Section: Wet Scattering Coefficient Measurements Vs the Mie Model Dumentioning

confidence: 53%

Seasonal variation of aerosol water uptake and its impact on the direct radiative effect at Ny-Ålesund, Svalbard

et al. 2014

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Abstract. In this study we investigated the impact of water uptake by aerosol particles in ambient atmosphere on their optical properties and their direct radiative effect (ADRE, W m −2 ) in the Arctic at Ny-Ålesund, Svalbard, during 2008. To achieve this, we combined three models, a hygroscopic growth model, a Mie model and a radiative transfer model, with an extensive set of observational data. We found that the seasonal variation of dry aerosol scattering coefficients showed minimum values during the summer season and the beginning

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Section: Wet Scattering Coefficient Measurements Vs the Mie Model Dumentioning

confidence: 53%

Seasonal variation of aerosol water uptake and its impact on the direct radiative effect at Ny-Ålesund, Svalbard

et al. 2014

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“…The wavelength dependence of scattering enhancement factor f (RH,λ) varies with generalized aerosol types. Kotchenruther and Hobbs (1998) and Zieger et al (2010Zieger et al ( , 2011 found no pronounced wavelength dependence of f (RH,λ) for biomass burning aerosols and arctic aerosols, respectively; Zieger et al (2013) found small variations (< 5 %) of f (RH,λ) at 450, 550, and 700 nm for several European sites; Kotchenruther et al (1999) and Magi and Hobbs (2003) reported significant wavelength dependence of f (RH,λ) for urban/industrial aerosols off the east coast of the United States. In this study, the wavelength dependence of enhancement factors was also investigated.…”

Section: Introductionmentioning

confidence: 99%

Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

et al. 2015

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Abstract. Scattering of solar radiation by aerosol particles is highly dependent on relative humidity (RH) as hygroscopic particles take up water with increasing RH. To achieve a better understanding of the effect of aerosol hygroscopic growth on light scattering properties and radiative forcing, the aerosol scattering coefficients at RH in the range of 40 to ∼ 90 % were measured using a humidified nephelometer system in the Yangtze River Delta of China in March 2013. In addition, the aerosol size distribution and chemical composition were measured. During the observation period, the mean and standard deviation (SD) of enhancement factors at RH = 85 % for the scattering coefficient (f (85 %)), backscattering coefficient (f b (85 %)), and hemispheric backscatter fraction (f β (85 %)) were 1.58 ± 0.12, 1.25 ± 0.07, and 0.79 ± 0.04, respectively, i.e., aerosol scattering coefficient and backscattering coefficient increased by 58 and 25 % as the RH increased from 40 to 85 %. Concurrently, the aerosol hemispheric backscatter fraction decreased by 21 %. The relative amount of organic matter (OM) or inorganics in PM 1 was found to be a main factor determining the magnitude of f (RH). The highest values of f (RH) corresponded to the aerosols with a small fraction of OM, and vice versa. The relative amount of NO − 3 in fine particles was strongly correlated with f (85 %), which suggests that NO − 3 played a vital role in aerosol hygroscopic growth during this study. The mass fraction of nitrate also had a close relationship to the curvature of the humidograms; higher mass fractions of nitrate were associated with humidograms that had the least curvature. Aerosol hygroscopic growth caused a 47 % increase in the calculated aerosol direct radiative forcing at 85 % RH, compared to the forcing at 40 % RH.

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“…For the hygroscopic particle growth the following parameterization (Petters and Kreidenweis, 2007;Zieger et al, 2013) r wet (RH)…”

Section: Calculation Of Optical Properties Of Particle Ensemblesmentioning

confidence: 99%

MOPSMAP v1.0: a versatile tool for the modeling of aerosol optical properties

Gasteiger

Wiegner²

2018

Geosci. Model Dev.

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Abstract. The spatiotemporal distribution and characterization of aerosol particles are usually determined by remotesensing and optical in situ measurements. These measurements are indirect with respect to microphysical properties, and thus inversion techniques are required to determine the aerosol microphysics. Scattering theory provides the link between microphysical and optical properties; it is not only needed for such inversions but also for radiative budget calculations and climate modeling. However, optical modeling can be very time-consuming, in particular if nonspherical particles or complex ensembles are involved.In this paper we present the MOPSMAP package (Modeled optical properties of ensembles of aerosol particles), which is computationally fast for optical modeling even in the case of complex aerosols. The package consists of a data set of pre-calculated optical properties of single aerosol particles, a Fortran program to calculate the properties of userdefined aerosol ensembles, and a user-friendly web interface for online calculations. Spheres, spheroids, and a small set of irregular particle shapes are considered over a wide range of sizes and refractive indices. MOPSMAP provides the fundamental optical properties assuming random particle orientation, including the scattering matrix for the selected wavelengths. Moreover, the output includes tables of frequently used properties such as the single-scattering albedo, the asymmetry parameter, or the lidar ratio. To demonstrate the wide range of possible MOPSMAP applications, a selection of examples is presented, e.g., dealing with hygroscopic growth, mixtures of absorbing and non-absorbing particles, the relevance of the size equivalence in the case of nonspherical particles, and the variability in volcanic ash microphysics.The web interface is designed to be intuitive for expert and nonexpert users. To support users a large set of default settings is available, e.g., several wavelength-dependent refractive indices, climatologically representative size distributions, and a parameterization of hygroscopic growth. Calculations are possible for single wavelengths or user-defined sets (e.g., of specific remote-sensing application). For expert users more options for the microphysics are available. Plots for immediate visualization of the results are shown. The complete output can be downloaded for further applications. All input parameters and results are stored in the user's personal folder so that calculations can easily be reproduced. The web interface is provided at https://mopsmap.net (last access: 9 July 2018) and the Fortran program including the data set is freely available for offline calculations, e.g., when large numbers of different runs for sensitivity studies are to be made.

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Effects of relative humidity on aerosol light scattering: results from different European sites

Cited by 207 publications

References 62 publications

Seasonal variation of aerosol water uptake and its impact on the direct radiative effect at Ny-Ålesund, Svalbard

Seasonal variation of aerosol water uptake and its impact on the direct radiative effect at Ny-Ålesund, Svalbard

Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

MOPSMAP v1.0: a versatile tool for the modeling of aerosol optical properties

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