Laboratory Validation of Aerosol Extinction Coefficient Measurements by a Field-Deployable Pulsed Cavity Ring-Down Transmissometer

Radney, James G.; Bazargan, Mohammad; Wright, Monica E.; Atkinson, Dean B.

doi:10.1080/02786820802482536

Cited by 30 publications

(42 citation statements)

References 29 publications

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“…The uncertainty in the measurements of these parameters has made it difficult to quantify the global impact of aerosols on Earth's climate (Hansen and Nazarenko 2004;Bond et al 2013). There has been an ongoing effort to develop a wide range of powerful aerosol measurement techniques, but there is still a need to develop instruments that can precisely and accurately measure the extensive and intensive optical properties of aerosols (Strawa et al 2003;Lack et al 2008;Moosmüller et al 2009;Radney et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Error Analysis and Uncertainty in the Determination of Aerosol Optical Properties Using Cavity Ring-Down Spectroscopy, Integrating Nephelometry, and the Extinction-Minus-Scattering Method

Singh

Fiddler

Smith

et al. 2014

Aerosol Science and Technology

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Despite the substantial improvements in the measurements of aerosol physical and chemical properties and in the direct and indirect radiative effects of aerosols, there is still a need for studying the properties of aerosols under controlled laboratory conditions to develop a mechanistic and quantitative understanding of aerosol formation, chemistry, and dynamics. In this work, we present the factors that affect measurement accuracy and the resulting uncertainties of the extinction-minus-scattering method using a combination of cavity ring-down spectroscopy (CRDS) and integrating nephelometry at a wider range of optical wavelengths than previously attempted. Purely scattering polystyrene latex (PSL) spheres with diameters from 107-303 nm and absorbing polystyrene spheres (APSL) with 390 nm diameter were used to determine the consistency and agreement, within experimental uncertainties, of CRDS and nephelometer values with theoretical calculations derived from Mie theory for non-absorbing spheres. Overall uncertainties for extinction cross-section were largely 10%-11% and dominated by condensation particle counter (CPC) measurement error. Two methods for determining σ ext error are described, and they were found to produce equivalent results. Systematic uncertainties due to particle losses, RD cell geometry (R L ), CPC counting efficiency, ring-down regression fitting, blank drift, optical tweezing, and recapturing of forward scattered light are also investigated. The random error observed in this work for absorbing spheres is comparable to previous reported measurements. For both absorbing and non-absorbing spheres, a statistical framework is developed for including the contributions to random error due to CPC measurement uncertainty, R L , statistical fluctuations in

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Section: Introductionmentioning

confidence: 99%

Error Analysis and Uncertainty in the Determination of Aerosol Optical Properties Using Cavity Ring-Down Spectroscopy, Integrating Nephelometry, and the Extinction-Minus-Scattering Method

Singh

Fiddler

Smith

et al. 2014

Aerosol Science and Technology

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“…A-CRDS is now routinely used in laboratory (Sappey et al 1998;Vander Wal and Ticich 1999;Smith and Atkinson 2001;Bulatov et al 2002Bulatov et al , 2003Bulatov et al , 2006Strawa et al 2003;Pettersson et al 2004;Baynard et al 2006;Garland et al 2007;Riziq et al 2007;Rudić et al 2007;Dinar et al 2008;Riziq et al 2008;Butler et al 2009;Freedman et al 2009;Khalizov et al 2009;Lang-Yona et al 2009Radney et al 2009;Xue et al 2009;Adler et al 2010;Hasenkopf et al 2010;Miles et al 2010aMiles et al , 2010b and field studies (Thompson et al 2002(Thompson et al , 2003Strawa et al 2006;Garland et al 2008;Nakayama et al 2010) to measure extinction by both aerosol ensembles (Vander Wal and Ticich 1999;Thompson et al 2002Thompson et al , 2003Thompson et al , 2008Strawa et al 2003;Pettersson et al 2004;Baynard et al 2006Baynard et al , 2007Garland et al 2007;Riziq et al 2007;Beaver et al 2008;…”

Section: Introductionmentioning

confidence: 99%

Sources of Error and Uncertainty in the Use of Cavity Ring Down Spectroscopy to Measure Aerosol Optical Properties

Miles

Rudić

Orr-Ewing

et al. 2011

Aerosol Science and Technology

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The use of cavity ring down spectroscopy to retrieve aerosol complex refractive index from optical property measurements has seen increasing popularity over the past few years. However, few studies have looked at the limit which sources of error and uncertainty inherent in the cavity ring down method place on the accuracy with which the refractive index can be retrieved. In this paper, we consider both experimental sources of error and those which compromise the theoretical models against which measurements are compared, both reviewing previously published work and presenting new data. Our results show that for absolute measurements made using single-cavity instruments, factors such as uncertainty in the length of the ring down cavity occupied by aerosol and the counting efficiency of the CPC can introduce an error of ∼2.5% into the real part of the refractive index retrieved from experiment. This is significantly higher than the typical 1% error quoted in previously published work. We note that due to the dependence of particle extinction efficiency on diameter, the effect of a given error on measurements for different particle sizes is not constant.

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“…Detailed information about these meteorological patterns and the properties of the corresponding air masses are reported in Wright et al (2009) for the UHMT site and in Bates et al (2008) and Massoli et al (2009) for the RHB. Figure 1 illustrates the overall RHB track in the area during the field study (panel 1a), with an enlarged view of the ship tracks in Houston/Galveston Bay and the Houston ship channel (panel 1b).…”

Section: Meteorological Conditions During the Case Study Periodmentioning

confidence: 99%

“…The PSU CRD measured σ ep at 532 and 1064 nm, with a maximum time resolution of 0.25 Hz, and a 95% confidence level detection limit of 4 Mm −1 based on previous laboratory data (Radney et al, 2008). The σ ep results presented here are averaged to at least 30 min, resulting in a detection limit of less than 1 Mm −1 (Wright et al, 2009). A Sequential Mobility Particle Sizer (SMPS) (GRIMM Technologies Inc.) was operated at the UHMT site throughout the project.…”

Section: Aerosol Sampling and Measurement Techniquesmentioning

confidence: 99%

Comparison of in situ and columnar aerosol spectral measurements during TexAQS-GoMACCS 2006: testing parameterizations for estimating aerosol fine mode properties

et al. 2010

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Abstract. During the 2006 Texas Air Quality Study and Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS-GoMACCS 2006), the optical, chemical and microphysical properties of atmospheric aerosols were measured on multiple mobile platforms and at ground based stations. In situ measurements of the aerosol light extinction coefficient (σ ep ) were performed by two multi-wavelength cavity ring-down (CRD) instruments, one located on board the NOAA R/V Ronald H. Brown (RHB) and the other located at the University of Houston, Moody Tower (UHMT). An AERONET sunphotometer was also located at the UHMT to measure the columnar aerosol optical depth (AOD). The σ ep data were used to extract the extinctionÅngström exponent (å ep ), a measure of the wavelength dependence of σ ep . There was general agreement between theå ep (and to a lesser degree σ ep ) measurements by the two spatially separated CRD instruments during multi-day periods, suggesting a regional scale consistency of the sampled aerosols. Two spectral models are applied to the σ ep and AOD data to extract the fine mode fraction of extinction (η) and the fine mode effective radius (R eff,f ). These two parameters are robust measures of the fine mode contribution to total extinction and the fine mode size distribution, respectively. The results of the analysis are compared to R eff,f values extracted using AERONET V2 retrievals and calculated from in situ particle size meaCorrespondence to: D. B. Atkinson (atkinsond@pdx.edu) surements on the RHB and at UHMT. During a time period when fine mode aerosols dominated the extinction over a large area extending from Houston/Galveston Bay and out into the Gulf of Mexico, the various methods for obtaining R eff,f agree qualitatively (showing the same temporal trend) and quantitatively (pooled standard deviation = 28 nm).

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Laboratory Validation of Aerosol Extinction Coefficient Measurements by a Field-Deployable Pulsed Cavity Ring-Down Transmissometer

Cited by 30 publications

References 29 publications

Error Analysis and Uncertainty in the Determination of Aerosol Optical Properties Using Cavity Ring-Down Spectroscopy, Integrating Nephelometry, and the Extinction-Minus-Scattering Method

Error Analysis and Uncertainty in the Determination of Aerosol Optical Properties Using Cavity Ring-Down Spectroscopy, Integrating Nephelometry, and the Extinction-Minus-Scattering Method

Sources of Error and Uncertainty in the Use of Cavity Ring Down Spectroscopy to Measure Aerosol Optical Properties

Comparison of in situ and columnar aerosol spectral measurements during TexAQS-GoMACCS 2006: testing parameterizations for estimating aerosol fine mode properties

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