Ultrafine particle scavenging coefficients calculated from 6 years field measurements

Laakso, Lauri; Grönholm, Tiia; Rannik, Üllar; Kosmale, Miriam; Fiedler, V.; Vehkamäki, Hanna; Kulmala, Markku

doi:10.1016/s1352-2310(03)00326-1

Cited by 170 publications

(243 citation statements)

References 18 publications

(29 reference statements)

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“…Below-cloud scavenging is fastest for particles larger than a few microns in diameter, moderate for particles smaller than 0.01 µm, and slowest for particles in the 0.1-1 µm diameter range. For example, the observed values were around 1x10 −4 s −1 to 3×10 −4 s −1 on average for particles in the 3.5-10 µm diameter range (Volken and Schumann, 1993), around 1x10 −4 s −1 for particles smaller than 0.01 µm (Davenport and Peters, 1978), and around 1×10 −5 s −1 on average for particles in the 0.1-1 µm diameter range (Laakso et al, 2003). The measurement data also have a large spread, which is probably due to the very different experimental conditions between these field studies.…”

Section: Evaluation Of Existing Theoretical and Empirical Size-resolvmentioning

confidence: 93%

“…A major advantage of Type II methods should be a significant reduction in computational burden since they need only evaluate a simple fitting function rather than performing an explicit integration over the raindrop size spectrum; however, one possible drawback of this method is that it might only be valid for certain rain droplet spectra. The third type of parameterization (hereafter referred to as Type III) uses an empirical fit to values derived from field measurements (Laakso et al, 2003;Baklanov and Sorensen, 2001). Table 3 lists some available size-resolved parameterizations classified by these three types.…”

Section: Evaluation Of Existing Theoretical and Empirical Size-resolvmentioning

confidence: 99%

“…The measurement data also have a large spread, which is probably due to the very different experimental conditions between these field studies. In general, values were determined by measuring concentration changes of the size-resolved aerosol particle at ground stations before, during, and after rain events (e.g., Davenport and Peters, 1978;Slinn, 1983;Volken and Schumann, 1993;Laakso et al, 2003;Chate and Pranesha, 2004). Besides the measurement errors caused by the instruments and analysis processes, many other physical (horizontal and vertical advection and turbulent diffusion), microphysical (condensation, nucleation, coagulation, and hygroscopic growth), and chemical (both gas-and aqueous-phase chemistry) processes can modify particle concentrations concurrently and thus contribute to the large uncertainties in the measured values.…”

Section: Evaluation Of Existing Theoretical and Empirical Size-resolvmentioning

confidence: 99%

“…Natural precipitation that fell through the chamber then Table 3 and taken from available measurements for rainfall intensities of (a) R = 1 mm h −1 , (b) R = 5 mm h −1 , and (c) R = 10 mm h −1 . Note that the parameterization of Laakso et al (2003) is only valid for particles with diameters between 0.01 and 0.5 µm.…”

Section: Evaluation Of Existing Theoretical and Empirical Size-resolvmentioning

confidence: 99%

“…Different choices have been made by different modelling groups but no systematic uncertainty assessment has been done on the sensitivity of to the choice of these input parameters. As for empirically-derived formulas (e.g., Laakso et al, 2003), while these formulas fit the data set from which they were derived well, they might not fit other data sets very well. Therefore, a systematic investigation of the uncertainties in the current theoretical and empirical-derived size-resolved parameterizations is needed in order to improve atmospheric aerosol CTMs.…”

Section: Introductionmentioning

confidence: 99%

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Uncertainty assessment of current size-resolved parameterizations for below-cloud particle scavenging by rain

Wang¹,

2010

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Abstract. Current theoretical and empirical size-resolved parameterizations of the scavenging coefficient ( ), a parameter commonly used in aerosol transport models to describe below-cloud particle scavenging by rain, have been reviewed in detail and compared with available field and laboratory measurements. Use of different formulations for raindropparticle collection efficiency can cause uncertainties in sizeresolved values of one to two orders of magnitude for particles in the 0.01-3 µm diameter range. Use of different formulations of raindrop number size distribution can cause values to vary by a factor of 3 to 5 for all particle sizes. The uncertainty in caused by the use of different droplet terminal velocity formulations is generally small than a factor of 2. The combined uncertainty due to the use of different formulations of raindrop-particle collection efficiency, raindrop size spectrum, and raindrop terminal velocity in the current theoretical framework is not sufficient to explain the one to two order of magnitude under-prediction of for the theoretical calculations relative to the majority of field measurements. These large discrepancies are likely caused by additional known physical processes (i.e, turbulent transport and mixing, cloud and aerosol microphysics) that influence field data but that are not considered in current theoretical parameterizations. The predicted size-resolved particle concentrations using different theoretical parameterization can differ by up to a factor of 2 for particles smaller than 0.01 µm and by a factor of >10 for particles larger than 3 µm after 2-5 mm of rain. The predicted bulk mass and number concentrations (integrated over the particle size distribution) can differ by a factor of 2 between theoretical and empirical parameterizations after 2-5 mm of moderate intensity rainfall.

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Section: Evaluation Of Existing Theoretical and Empirical Size-resolvmentioning

confidence: 93%

Section: Evaluation Of Existing Theoretical and Empirical Size-resolvmentioning

confidence: 99%

Section: Evaluation Of Existing Theoretical and Empirical Size-resolvmentioning

confidence: 99%

Section: Evaluation Of Existing Theoretical and Empirical Size-resolvmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Uncertainty assessment of current size-resolved parameterizations for below-cloud particle scavenging by rain

Wang¹,

2010

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Global observations of aerosol-cloud-precipitation-climate interactions

et al. 2014

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Cloud drop condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and, consequently, cloud albedo and the dynamic response of clouds to aerosol-induced changes to precipitation. This can modify the reflected solar radiation and the thermal radiation emitted to space. Measurements of tropospheric CCN and IN over large areas have not been possible and can be only roughly approximated from satellite-sensor-based estimates of optical properties of aerosols. Our lack of ability to measure both CCN and cloud updrafts precludes disentangling the effects of meteorology from those of aerosols and represents the largest component in our uncertainty in anthropogenic climate forcing. Ways to improve the retrieval accuracy include multiangle and multipolarimetric passive measurements of the optical signal and multispectral lidar polarimetric measurements. Indirect methods include proxies of trace gases, as retrieved by hyperspectral sensors. Perhaps the most promising emerging direction is retrieving the CCN properties by simultaneously retrieving convective cloud drop number concentrations and updraft speeds, which amounts to using clouds as natural CCN chambers. These satellite observations have to be constrained by in situ observations of aerosol-cloud-precipitation-climate (ACPC) interactions, which in turn constrain a hierarchy of model simulations of ACPC. Since the essence of a general circulation model is an accurate quantification of the energy and mass fluxes in all forms between the surface, atmosphere and outer space, a route to progress is proposed here in the form of a series of box flux closure experiments in the various climate regimes. A roadmap is provided for quantifying the ACPC interactions and thereby reducing the uncertainty in anthropogenic climate forcing.

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Emission, Transformation, and Fate of Nanoparticles in the Atmosphere

Kumar¹,

Al‐Dabbous²

2016

Engineered Nanoparticles and the Environment: Biophysicochemical Processes and Toxicity

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Ultrafine particle scavenging coefficients calculated from 6 years field measurements

Cited by 170 publications

References 18 publications

Uncertainty assessment of current size-resolved parameterizations for below-cloud particle scavenging by rain

Uncertainty assessment of current size-resolved parameterizations for below-cloud particle scavenging by rain

Global observations of aerosol-cloud-precipitation-climate interactions

Emission, Transformation, and Fate of Nanoparticles in the Atmosphere

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