Influence of water uptake on the aerosol particle light scattering
                        coefficients of the Central European aerosol

Zieger, Paul; Fierz-Schmidhauser, R.; Poulain, Laurent; Müller, Thomas; Birmili, W.; Spindler, Gerald; Wiedensohler, Alfred; Baltensperger, Urs; Weingärtner, E.

doi:10.3402/tellusb.v66.22716

Cited by 71 publications

(72 citation statements)

References 57 publications

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“…However, the differences are mostly under 10 % and therefore the discussion is focused on 550 nm wavelength in this study. Similar results were obtained by Zieger at a regional continental research site in Melpitz, Germany (Zieger et al, 2014). …”

Section: Wavelength Dependence Of the Scattering Enhancement Factor Fsupporting

confidence: 87%

“…The absolute values of both slopes (1.2 for f (85 %) vs. organic mass fraction and 0.96 for f (85 %) vs. inorganic mass fraction) were much lower than those (3.1 and 2.2, respectively) measured at Melpitz, Germany (Zieger et al, 2014). This may partly be due to the higher organic (or lower inorganic) content at Lin'an.…”

Section: The Relationship Of Scattering Enhancement Factor With Chemicontrasting

confidence: 38%

“…The scattering enhancement factor f (RH) can be parameterized with empirical equations (Kotchenruther and Hobbs, 1998;Kotchenruther et al, 1999;Gassó et al, 2000;Carrico et al, 2003;Liu et al, 2008;Zieger et al, 2010;Zieger et al, 2014). Humidograms from Lin'an were fitted with two empirical equations and the fitting results are shown below.…”

Section: Parameterization Of Scattering Enhancement Factor F (Rh)mentioning

confidence: 99%

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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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Section: Wavelength Dependence Of the Scattering Enhancement Factor Fsupporting

confidence: 87%

Section: The Relationship Of Scattering Enhancement Factor With Chemicontrasting

confidence: 38%

Section: Parameterization Of Scattering Enhancement Factor F (Rh)mentioning

confidence: 99%

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

et al. 2015

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“…Continental aerosols (e.g. f (85 %, 550 nm) ≈ 1.8-2.8; Zieger et al, 2012Zieger et al, , 2014Fierz-Schmidhauser et al, 2010b;Koloutsou-Vakakis et al, 2001;Sheridan et al, 2001) and urban aerosols (e.g. f (85 %, 550 nm) ≈ 1.3-1.6; Titos et al, 2014b;Zieger et al, 2011;McInnes et al, 1998;Fitzgerald et al, 1982) are observed with intermediate values.…”

Section: Introductionmentioning

confidence: 96%

Low hygroscopic scattering enhancement of boreal aerosol and the implications for a columnar optical closure study

et al. 2015

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Abstract. Ambient aerosol particles can take up water and thus change their optical properties depending on the hygroscopicity and the relative humidity (RH) of the surrounding air. Knowledge of the hygroscopicity effect is of crucial importance for radiative forcing calculations and is also needed for the comparison or validation of remote sensing or model results with in situ measurements. Specifically, particle light scattering depends on RH and can be described by the scattering enhancement factor f (RH), which is defined as the particle light scattering coefficient at defined RH divided by its dry value (RH < 30-40 %).Here, we present results of an intensive field campaign carried out in summer 2013 at the SMEAR II station at Hyytiälä, Finland. Ground-based and airborne measurements of aerosol optical, chemical and microphysical properties were conducted. The f (RH) measured at ground level by a humidified nephelometer is found to be generally lower (e.g. 1.63 ± 0.22 at RH = 85 % and λ = 525 nm) than observed at other European sites. One reason is the high organic mass fraction of the aerosol encountered at Hyytiälä to which f (RH) is clearly anti-correlated (R 2 ≈ 0.8). A simplified parametrization of f (RH) based on the measured chemical mass fraction can therefore be derived for this aerosol type. A trajectory analysis revealed that elevated values of f (RH) and the corresponding elevated inorganic mass fraction are partially caused by transported hygroscopic sea spray particles. An optical closure study shows the consistency of the ground-based in situ measurements.Our measurements allow to determine the ambient particle light extinction coefficient using the measured f (RH). By combining the ground-based measurements with intensive aircraft measurements of the particle number size distribution and ambient RH, columnar values of the particle extinction coefficient are determined and compared to columnar measurements of a co-located AERONET sun photometer. The water uptake is found to be of minor importance for the column-averaged properties due to the low particle hygroscopicity and the low RH during the daytime of the summer months. The in situ derived aerosol optical depths (AOD) clearly correlate with directly measured values of the sun photometer but are substantially lower compared to the directly measured values (factor of ∼ 2-3). The comparison degrades for longer wavelengths. The disagreement between in situ derived and directly measured AOD is hypothesized Published by Copernicus Publications on behalf of the European Geosciences Union. 7248 P. Zieger et al.: Scattering enhancement of boreal aerosol and columnar closure study to originate from losses of coarse and fine mode particles through dry deposition within the canopy and losses in the in situ sampling lines. In addition, elevated aerosol layers (above 3 km) from long-range transport were observed using an aerosol lidar at Kuopio, Finland, about 200 km east-northeast of Hyytiälä. These elevated layers further explain parts of the disagree...

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“…It is required, for example, for closure experiments (consistency checks between different measurement methods involving an aerosol model, e.g., Wiegner et al, 2009;Gasteiger et al, 2011b;Müller et al, 2012;Bell et al, 2013;Ma et al, 2014;Zieger et al, 2014;Düsing et al, 2018), radiative transfer studies (e.g., Otto et al, 2009;Emde et al, 2010), the inversion of remote-sensing measurements (e.g., Dubovik et al, 2006;Gasteiger et al, 2011a;Müller et al, 2016), the inversion of in situ data (e.g., Weinzierl et al, 2009;Szymanski et al, 2009;Kassianov et al, 2014), aerosol layer visibility simulations (e.g., Weinzierl et al, 2012), dynamic aerosol transport models (e.g., Heinold et al, 2007;Balzarini et al, 2015), aerosol characterization (e.g., Gasteiger et al, 2017;Che et al, 2018;Zhuang et al, 2018), and solar energy (e.g., Polo et al, 2016;Kosmopoulos et al, 2017).…”

Section: Applicationsmentioning

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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Influence of water uptake on the aerosol particle light scattering coefficients of the Central European aerosol

Cited by 71 publications

References 57 publications

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

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

Low hygroscopic scattering enhancement of boreal aerosol and the implications for a columnar optical closure study

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

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