scholarly journals Implementing growth and sedimentation of NAT particles in a global Eulerian model

2004 ◽  
Vol 4 (7) ◽  
pp. 1869-1883 ◽  
Author(s):  
M. M. P. van den Broek ◽  
J. E. Williams ◽  
A. Bregman
Keyword(s):  
Particle Number ◽  
Transport Model ◽  
Particle Diameter ◽  
Particle Growth ◽  
Particle Number Density ◽  
Lagrangian Model ◽  
Number Density ◽  
Model Study ◽  
Total Particle Number ◽  
Total Particle

Abstract. Here we present a concise and efficient algorithm to mimic the growth and sedimentation of Nitric Acid Trihydate (NAT) particles in the polar vortex in a state-of-the-art 3D chemistry transport model. The particle growth and sedimentation are calculated using the microphysical formulation of Carslaw et al. (2002). Once formed, NAT particles are transported in the model as tracers in the form of size-segregated quantities or size bins. Two different approaches were adopted for this purpose: one assuming a fixed particle number density ("FixedDens") and the other assuming a discrete set of particle diameter values ("FixedRad"). Simulations were performed for three separate 10-day periods during the 1999-2000 Arctic winter and compared to the results of an existing Lagrangian model study, which uses similar microphysics in a computationally more expensive method for the simulation of NAT particle growth. The resulting particle sizes for both our approaches compare favourably at 430K with those obtained from this previous model study, and also in-situ observations related to the size of large NAT particles. The particle growth is faster for "FixedDens" resulting in a difference in (de)nitrification by a factor of ~2 for all three simulation periods. Comparisons were made with a standard equilibrium approach and the differences in the redistribution of HNO3 were found to be substantial. For both approaches the performance of the algorithm is rather insensitive to both the number of size bins and the shape of the size distribution, and show a weak dependence on the prescribed total particle number density during the coldest period. This results in an increase of 7% for the "FixedRad" approach and 17% for the "FixedDens" approach when increasing the total particle number density by a factor of 2.5.

scholarly journals Implementing growth and sedimentation of NAT particles in a global Eulerian model

2004 ◽  
Vol 4 (3) ◽  
pp. 3089-3126
Author(s):  
M. M. P. van den Broek ◽  
J. E. Williams ◽  
A. Bregman
Keyword(s):  
Transport Model ◽  
Particle Diameter ◽  
Polar Vortex ◽  
Particle Growth ◽  
Particle Number Density ◽  
Lagrangian Model ◽  
Number Density ◽  
Model Study ◽  
Maximum Particle

Abstract. Here we present a concise and efficient algorithm to mimic the growth and sedimentation of Nitric Acid Trihydate (NAT) particles in the polar vortex in a state-of-the-art 3D chemistry transport model. The particle growth and sedimentation are calculated using the microphysical formulation of Carslaw et al. (2002). Once formed, NAT particles are transported in the model as tracers in the form of size-segregated quantities. Two different approaches were adopted for this purpose: one assuming a fixed particle number density ("FixedDens") and the other assuming a discrete set of particle diameter values ("FixedRad"). Simulations were performed for three separate 10-day periods during the 1999–2000 Arctic winter and compared to the results of an existing Lagrangian model study, which uses similar microphysics in a computationally more expensive method for the simulation of NAT particle growth. The resulting maximum particle sizes for both our approaches compare favourably at 96 hPa with those obtained from this previous model study, and also in-situ observations related to the size of large NAT particles. Comparisons were made with a standard equilibrium approach and the differences in the redistribution of HNO3 were found to be substantial. For both approaches the performance of the algorithm is rather insensitive to both the number of size bins and the shape of the size distribution. However, the percentage of HNO3 sequestered into NAT is critically dependent on the total number density of particles prescribed for each size bin.

Particle Absorption and Scatter

2006 ◽  
Author(s):  
Michael E. Thomas
Keyword(s):  
Unit Volume ◽  
Particle Number ◽  
Mie Scattering ◽  
Particle Number Density ◽  
Number Density ◽  
Shape Variation ◽  
Propagation Modeling ◽  
Total Particle Number ◽  
Total Particle ◽  
Unit Radius

Particles are composed of solids and/or liquids, thus the bulk optical properties of these media must be known before propagation modeling within a medium of suspended particles (called aerosols when in air) can begin. We return to our discussion of propagation in the atmosphere and oceans of the earth that began in Chapters 7 and 9, and we now include attenuation by small particles. Particles vary in size, shape, concentration, and composition. Size and concentration distributions are described in the following two sections. The composition of the most common particles is presented in the last section. Unfortunately, a representation of shape variation does not exist. As mentioned in Chapter 4 (Section 4.4.2 on Mie scattering), a collection of real aerosols will have a range of different radii. This is called a polydisperse medium. Various models are used to represent particle size distributions. One commonly used model for particle number density as a function of radius is the modified gamma distribution function, as given by . . . ρp(r) = Arα exp(−brγ), (10.1) . . . where A, b, α, and γ are empirically determined parameters. This function represents the number of particles per unit volume and unit radius as a function of radius r. The total particle number density is obtained by integrating ρp(r ) over all r.

scholarly journals Long-Term Characterization of Submicron Atmospheric Particles in an Urban Background Site in Southern Italy

Atmosphere ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 334 ◽  
Author(s):  
Adelaide Dinoi ◽  
Marianna Conte ◽  
Fabio M. Grasso ◽  
Daniele Contini
Keyword(s):  
Particle Number ◽  
Meteorological Parameters ◽  
Particle Diameter ◽  
Number Concentration ◽  
Total Particle Number ◽  
Total Particle ◽  
Late Evening ◽  
20 Nm

Continuous measurements of particle number size distributions in the size range from 10 nm to 800 nm were performed from 2015 to 2019 at the ECO Environmental-Climate Observatory of Lecce (Global Atmosphere Watch Programme/Aerosol, Clouds and Trace Gases Research Infrastructure (GAW/ACTRIS) regional station). The main objectives of this work were to investigate the daily, weekly and seasonal trends of particle number concentrations and their dependence on meteorological parameters gathering information on potential sources. The highest total number concentrations were observed during autumn-winter with average values nearly twice as high as in summer. More than 52% of total particle number concentration consisted of Aitken mode (20 nm < particle diameter (Dp) < 100 nm) particles followed by accumulation (100 nm < Dp < 800 nm) and nucleation (10 nm < Dp < 20 nm) modes representing, respectively, 27% and 21% of particles. The total number concentration was usually significantly higher during workdays than during weekends/holidays in all years, showing a trend likely correlated with local traffic activities. The number concentration of each particle mode showed a characteristic daily variation that was different in cold and warm seasons. The highest concentrations of the Aitken and accumulation particle mode were observed in the morning and the late evening, during typical rush hour traffic times, highlighting that the two-particle size ranges are related, although there was significant variation in the number concentrations. The peak in the number concentrations of the nucleation mode observed in the midday of spring and summer can be attributed to the intensive formation of new particles from gaseous precursors. Based on Pearson coefficients between particle number concentrations and meteorological parameters, temperature, and wind speed had significant negative relationships with the Aitken and accumulation particle number concentrations, whereas relative humidity was positively correlated. No significant correlations were found for the nucleation particle number concentrations.

The Dependence of Pool Scrubbing Decontamination Factor on Particle Number Density: Modeling Based on Bubble Mass and Energy Balance

2020 ◽  
Author(s):  
Yasuteru Sibamoto ◽  
Haomin Sun ◽  
Yoshiyasu Hirose ◽  
Yutaka Kukita
Keyword(s):  
Energy Balance ◽  
Particle Number ◽  
Sharp Decrease ◽  
Particle Growth ◽  
Decontamination Factor ◽  
Particle Number Density ◽  
Vapor Condensation ◽  
Vapor Concentration ◽  
Number Density ◽  
Condensational Growth

Abstract The dependence of pool scrubbing performance on particle number density is studied through numerical simulation of experimental results. The DF values obtained from the authors’ experiments (Sun et al., Sci. Technol. Nucl. Inst., Article ID 1743982, 2019) indicate a sharp decrease with an increase in the inlet particle number density beyond 1011/m3. The mechanisms underlying such dependence is yet to be studied. In this paper, a simple model is developed to study the factors affecting the experimentally observed dependence of DF. The test results suggest that the condensational growth of particles plays an essential role in the inertial capture. The vapor condensation on the particles has an effect to deplete the vapor supersaturation in the bubble by both lowering the vapor concentration and raising the temperature. This effect will become important at high particle number densities. The bubble mass and energy balance is calculated to derive the particle growth and the inertial DF as a function of the bubble rise distance through the pool water. The balance is assumed to be quasi-steady, and the vapor concentration and the temperature to be uniform in the bubble. It is shown that the model reproduces the tendency observed in the experimental DF. The model predicts that the degree of supersaturation is affected when particle concentration exceeds 1011/m3, curbing the condensational growth of particles, and thereby retarding the inertial capture.

scholarly journals Simulating ultrafine particle formation in Europe using a regional CTM: contribution of primary emissions versus secondary formation to aerosol number concentrations

2012 ◽  
Vol 12 (18) ◽  
pp. 8663-8677 ◽  
Author(s):  
C. Fountoukis ◽  
I. Riipinen ◽  
H. A. C. Denier van der Gon ◽  
P. E. Charalampidis ◽  
C. Pilinis ◽  
...  
Keyword(s):  
Particle Number ◽  
Transport Model ◽  
Eastern Mediterranean ◽  
Lower Troposphere ◽  
Southeast Europe ◽  
Chemical Transport Model ◽  
The Balkans ◽  
Total Particle Number ◽  
Secondary Formation ◽  
Total Particle

Abstract. A three-dimensional regional chemical transport model (CTM) with detailed aerosol microphysics, PMCAMx-UF, was applied to the European domain to simulate the contribution of direct emissions and secondary formation to total particle number concentrations during May 2008. PMCAMx-UF uses the Dynamic Model for Aerosol Nucleation and the Two-Moment Aerosol Sectional (TOMAS) algorithm to track both aerosol number and mass concentration using a sectional approach. The model predicts nucleation events that occur over scales of hundreds up to thousands of kilometers especially over the Balkans and Southeast Europe. The model predictions were compared against measurements from 7 sites across Europe. The model reproduces more than 70% of the hourly concentrations of particles larger than 10 nm (N10) within a factor of 2. About half of these particles are predicted to originate from nucleation in the lower troposphere. Regional nucleation is predicted to increase the total particle number concentration by approximately a factor of 3. For particles larger than 100 nm the effect varies from an increase of 20% in the eastern Mediterranean to a decrease of 20% in southern Spain and Portugal resulting in a small average increase of around 1% over the whole domain. Nucleation has a significant effect in the predicted N50 levels (up to a factor of 2 increase) mainly in areas where there are condensable vapors to grow the particles to larger sizes. A semi-empirical ternary sulfuric acid-ammonia-water parameterization performs better than the activation or the kinetic parameterizations in reproducing the observations. Reducing emissions of ammonia and sulfur dioxide affects certain parts of the number size distribution.

scholarly journals Measurement report: Three years of size-resolved eddy-covariance particle number flux measurements in an urban environment

2021 ◽  
Vol 21 (24) ◽  
pp. 18707-18726
Author(s):  
Agnes Straaten ◽  
Stephan Weber
Keyword(s):  
Eddy Covariance ◽  
Ultrafine Particles ◽  
Particle Number ◽  
Particle Diameter ◽  
Urban Site ◽  
Size Spectrum ◽  
Slight Reduction ◽  
The Third ◽  
Total Particle Number ◽  
Total Particle

Abstract. Size-resolved particle number fluxes in the size range of 10 nm < particle diameter (Dp) < 200 nm were measured over a 3-year period (April 2017–March 2020) using the eddy-covariance technique at an urban site in Berlin, Germany. The observations indicated the site as a net source of particles with a median total particle number flux of FTNC=0.86 × 108 m−2 s−1. The turbulent surface–atmosphere exchange of particles was clearly dominated by ultrafine particles (Dp < 100 nm) with a share of 96 % of total particle number flux (FUFP=0.83 × 108 m−2 s−1). Annual estimates of median FTNC and FUFP slightly decreased by −9.6 % (−8.9 % for FUFP) from the first to the second observation year and a further −5.9 % (−6.1 % for FUFP) from the second to the third year. The annual variation might be due to different reasons such as the variation of flux footprints in the individual years, a slight reduction of traffic intensity in the third year, or a progressive transition of the vehicle fleet towards a higher share of low-emission standards or electric drive. Size-resolved measurements illustrated events of bidirectional fluxes, i.e. simultaneous emission and deposition fluxes within the size spectrum, which occurred more often in spring, late summer, and autumn than in winter. Multi-year observations of size-resolved particle fluxes proved to be important for a deeper understanding of particle exchange processes with the urban surface and the pronounced influence of traffic at this urban site.

scholarly journals Simulating ultrafine particle formation in Europe using a regional CTM: contribution of primary emissions versus secondary formation to aerosol number concentrations

2012 ◽  
Vol 12 (6) ◽  
pp. 13581-13617 ◽  
Author(s):  
C. Fountoukis ◽  
I. Riipinen ◽  
H. A. C. Denier van der Gon ◽  
P. E. Charalampidis ◽  
C. Pilinis ◽  
...  
Keyword(s):  
Particle Number ◽  
Transport Model ◽  
Eastern Mediterranean ◽  
Lower Troposphere ◽  
Southeast Europe ◽  
Chemical Transport Model ◽  
The Balkans ◽  
Total Particle Number ◽  
Secondary Formation ◽  
Total Particle

Abstract. A three-dimensional regional chemical transport model (CTM) with detailed aerosol microphysics, PMCAMx-UF, was applied to the European domain to simulate the contribution of direct emissions and secondary formation to total particle number concentrations during May 2008. PMCAMx-UF uses the Dynamic Model for Aerosol Nucleation and the Two-Moment Aerosol Sectional (TOMAS) algorithm to track both aerosol number and mass concentration using a sectional approach. The model predicts nucleation events that occur over scales of hundreds up to thousands of kilometers especially over the Balkans and Southeast Europe. The model predictions were compared against measurements from 7 sites across Europe. The model reproduces more than 70% of the hourly concentrations of particles larger than 10 nm (N10) within a factor of 2. About half of these particles are predicted to originate from nucleation in the lower troposphere. Regional nucleation is predicted to increase the total particle number concentration by approximately a factor of 3. For particles larger than 100 nm the effect varies from an increase of 20% in the eastern Mediterranean to a decrease of 20% in southern Spain and Portugal resulting in a small average increase of around 1% over the whole domain. Nucleation has a significant effect in the predicted N50 levels (up to a factor of 2 increase) mainly in areas where there are condensable vapors to grow the particles to larger sizes. A semi-empirical ternary sulfuric acid-ammonia-water parameterization performs better than the activation or the kinetic parameterizations in reproducing the observations. Reducing emissions of ammonia and sulfur dioxide affects certain parts of the number size distribution.

scholarly journals Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

2013 ◽  
Vol 13 (15) ◽  
pp. 7473-7487 ◽  
Author(s):  
E. Järvinen ◽  
A. Virkkula ◽  
T. Nieminen ◽  
P. P. Aalto ◽  
E. Asmi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Seasonal Cycle ◽  
Particle Number ◽  
Formation Rate ◽  
Particle Growth ◽  
Particle Formation ◽  
Distribution Data ◽  
New Particle Formation ◽  
Total Particle Number ◽  
Total Particle

Abstract. We studied new particle formation and modal behavior of ultrafine aerosol particles on the high East Antarctic plateau at the Concordia station, Dome C (75°06' S, 123°23' E). Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, natural new particle formation was observed on 60 days and for 15 of these days the particle growth rates from 10 to 25 nm in size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed at other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events slowly growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in central Antarctica.

scholarly journals Measurement report: Three years of size-resolved eddy-covariance particle number flux measurements in an urban environment

2021 ◽  
Author(s):  
Agnes Straaten ◽  
Stephan Weber
Keyword(s):  
Eddy Covariance ◽  
Ultrafine Particles ◽  
Particle Number ◽  
Particle Diameter ◽  
Urban Site ◽  
Size Spectrum ◽  
Slight Reduction ◽  
The Third ◽  
Total Particle Number ◽  
Total Particle

Abstract. Size-resolved particle number fluxes in the size range 10 nm <  particle diameter (Dp) < 200 nm were measured over a 3-year period (April 2017–March 2020) using the eddy covariance technique at an urban site in Berlin, Germany. The observations indicated the site as a net source of particles with a median total particle number flux of FTNC = 0.86 × 108 m−2 s−1. The turbulent surface-atmosphere exchange of particles was clearly dominated by ultrafine particles (Dp < 100 nm) with a share of 96 % of total particle number flux (FUFP = 0.83 × 108 m−2 s−1). Annual estimates of median FTNC and FUFP slightly decreased by −9.6 % (−8.9 % for FUFP) from the first to the second observation year and a further −5.9 % (−6.1 % for FUFP) from the second to the third year. The annual variation might be due to different reasons such as variation of flux footprints in the individual years, a slight reduction of traffic intensity in the third year or a progressive transition of the vehicle fleet towards a higher share of low-emission standards or electric drive. Size-resolved measurements illustrated events of bidirectional fluxes, i.e. simultaneous emission and deposition fluxes within the size spectrum, which occurred more often in spring, late summer and autumn than in winter. Multi-year observations of size-resolved particle fluxes proved to be important for deeper understanding of particle exchange processes with the urban surface and the pronounced influence of traffic at this urban site.

scholarly journals Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

2013 ◽  
Vol 13 (3) ◽  
pp. 5729-5768
Author(s):  
E. Järvinen ◽  
A. Virkkula ◽  
T. Nieminen ◽  
P. P. Aalto ◽  
E. Asmi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Seasonal Cycle ◽  
Particle Number ◽  
Formation Rate ◽  
Particle Growth ◽  
Particle Formation ◽  
Distribution Data ◽  
New Particle Formation ◽  
Total Particle Number ◽  
Total Particle

Abstract. We studied new particle formation and modal behavior of ultrafine aerosol particles on the high Antarctic East-Plateau at the Concordia station, Dome C (75°06' S, 123°23' E). Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, new particle formation was seen on 80 days and for 15 of these days the particle growth rates from 10 to 25 nm size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed in other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events as slowly-growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in the central Antarctica.

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