Improved Inversion of Scanning DMA Data

Collins, D. R.; Flagan, Richard C.; Seinfeld, John H.

doi:10.1080/027868202753339032

Cited by 149 publications

(130 citation statements)

References 27 publications

(39 reference statements)

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“…The SMPS data were inverted using the schema by Collins et al (2002). All the data, except the particle size distributions measured with the SMPS were recorded at 1 Hz.…”

Section: Airborne Instrumentation and Data Preparationmentioning

confidence: 99%

Vertical and horizontal variation of aerosol number size distribution in the boreal environment

Väänänen

Krejci

Manninen

et al. 2016

Preprint

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15This study explores the vertical and horizontal variability of the particle number size distribution from two flight measurements campaigns over a boreal forest in Hyytiälä, Finland during May-June 2013 and March-April 2014, respectively. Our other aims were to study the spatial extent of new particle formation events and to compare the airborne observation with the ground measurements from the SMEAR II (Station for Measuring Ecosystem-Atmosphere Relations) field station located in Hyytiälä.The airborne measurements extended vertically 3.8 km and horizontally 30 km from the station. A Cessna 172 aircraft was 20 used as a measurement platform. The measured parameters included the particle number concentration (>3 nm) and particle number size distribution (10-400 nm). The airborne data used in this study were equal to 111 flight hours. The measurements showed that despite local fluctuations there was a good agreement between the on-ground and airborne measurements inside the planetary boundary layer. On median, the airborne total number concentration was found to be 10 % larger than at the ground level. The seasonal and meteorological differences between the campaigns were reflected in aerosol properties. NPF 25 days showed areas of intensified NPF on a scale from kilometres up to couple of tens of kilometres in the planetary boundary layer. NPF was also observed frequently in the free troposphere.Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016Discuss., doi:10.5194/acp- -556, 2016 Manuscript under review for journal Atmos. Chem. Phys. Published: 18 July 2016 c Author(s) 2016. CC-BY 3.0 License. 2 IntroductionAtmospheric measurements performed at ground-based stations are often generalized to represent the conditions on the larger scale. However, the spatial and temporal scales of the complex atmospheric phenomena, like new particle formation (NPF), and information on spatial variability of aerosol properties is needed for correct extrapolation and parametrization of groundbased observations to larger scale and for use in modelling studies. 5Numerous measurement have shown that the NPF from precursor gases (Kulmala et al. 2013) occurs frequently around the world (Kulmala and Kerminen 2008, Kulmala et al. 2004, Zhang et al. 2012, and that the subsequent growth of these fresh-born particles is a climatically important source of cloud condensation nuclei (CCN) . Model studies by Spracklen et al (2008) and Merikanto et al (2009) show that NPF in the planetary boundary layer (PBL) can increase the global PBL CCN production up to 50 %. The Hyytiälä SMEAR II (Station for Measuring Ecosystem-10Atmosphere Relations) measurement site located in Southern Finland has provided an extensive two-decade long measurement time series of aerosol properties in a rural boreal forest environment (Hari and Kulmala 2005, Nieminen et al. 2014). In Hyytiälä, NPF days are occurring regularly on around 25% of the days with a peak observed during the spring when NPF occurs almost every other day on average , Nieminen et al. 2014....

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“…The SMPS data were inverted using the schema by Collins et al (2002). All the data, except the particle size distributions measured with the SMPS were recorded at 1 Hz.…”

Section: Airborne Instrumentation and Data Preparationmentioning

confidence: 99%

Vertical and horizontal variation of aerosol number size distribution in the boreal environment

Väänänen

Krejci

Manninen

et al. 2016

Preprint

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“…A TSI 3025 CPC was used to detect the classified aerosol since its low mixing time constant minimizes smearing of the recovered distribution during rapid scans (Russell et a!. 1995;Collins et al 2002). The experimental counting time interval used was chosen to provide adequate counting statistics.…”

Section: Experimental Verificationmentioning

confidence: 99%

The Scanning DMA Transfer Function

Collins

Cocker

Flagan

et al. 2004

Aerosol Science and Technology

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The scanning differential mobility analyzer (DMA) has been widely employed for measurement of rapidly evolving aerosol size distributions. Interpretation of data from scanning DMAs is greatly facilitated when an exponential voltage ramp is prescribed, since the shape of the instrumental transfer function remains constant throughout a scan. However, that transfer function may differ significantly from that expected for fixed voltage operation. Because no simple analytical description of the scanning DMA transfer function exists, it has been evaluated numerically by simulating particle trajectories within a TSI 3081 cylindrical DMA. These computations yield transfer functions for the DMA up scan that are roughly triangular but with widths significantly greater than those for fixed voltage operation, and transfer functions for the down scan that are highly asymmetric. The impact of these distortions is most obvious when the size distribution of the measured aerosol is narrow, but errors in recovered size and concentration can be significant even when the aerosol size distribution is much broader than the transfer function. The magnitude of these errors is dependent upon the ratio of the mean gas residence time to the exponential voltage time constant, the sheath-to-aerosol-flow ratio, and the technique used to determine the instrument plumbing time. Experimental results for scans across broad and narrow size distributions compare favorably with predictions based on the simulated transfer functions. Simplified corrections are provided that can be used to adjust the concentration and mobility of size distributions recovered using a fixed voltage transfer function.

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“…High resolving power aerosol particle classification by electrical mobility was made possible by the cylindrical differential mobility analyzer (DMA; Knutson and Whitby 1975). In a continuous scanning mode, such devices can classify aerosols across their entire dynamic ranges in under a minute (Wang and Flagan 1990), or even in a few seconds by using fast-response detectors (Collins et al 2002;Shah and Cocker 2005). A variety of custom-made and commercially available instruments enable investigators to remotely monitor the evolution of aerosol populations ranging from 1 nm to 10 µm.…”

Section: Introductionmentioning

confidence: 99%

An Asymptotic Analysis of Differential Electrical Mobility Classifiers

Downard

Dama

Flagan

2011

Aerosol Science and Technology

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An asymptotic analysis of balanced flow operations of differential mobility analyzers (DMAs) and a new class of instruments that includes opposed migration aerosol classifiers (OMACs) and inclined grid mobility analyzers (IGMAs) provides new insights into the similarities and differences between the devices. The characteristic scalings of different instruments found from minimal models are shown to relate the resolving powers, dynamic ranges, and efficiencies of most such devices. The resolving powers of all of the instruments in the nondiffusive regime of high voltage classifications, R nd , is determined by the ratio of the flow rate of the separation gas (sheath or crossflow) to that of the aerosol. At low voltage, when diffusion degrades the classification, the OMAC and the IGMA share an R nd factor advantage in dynamic range of mobilities over the DMA, although the OMAC also suffers greater losses because diffusion immediately deposits particles onto its porous electrodes. On the basis of this analysis, a single master operating diagram is proposed for DMAs, OMACs, and IGMAs. Analysis of this operating diagram and its consequences for the design of differential electrical mobility classifiers suggests that OMACs and IGMAs also have advantages over DMAs in design flexibility and miniaturization. Most importantly, OMACs and IGMAs may outperform DMAs for the currently difficult classification of particles with diameters less than 10 nm. On the other hand, DMAs are more amenable to voltage scanning-mode operation to enable accelerated size distribution measurements, whereas it is most convenient to operate OMACs and IGMAs in voltage stepping-mode operation.

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Improved Inversion of Scanning DMA Data

Cited by 149 publications

References 27 publications

Vertical and horizontal variation of aerosol number size distribution in the boreal environment

Vertical and horizontal variation of aerosol number size distribution in the boreal environment

The Scanning DMA Transfer Function

An Asymptotic Analysis of Differential Electrical Mobility Classifiers

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