Scavenging of aerosol particles by rain in a cloud resolving model

Berthet, Sarah; Leriche, Maud; Pinty, J. P.; Cuesta, Juan; Pigeon, Grégoire

doi:10.1016/j.atmosres.2009.09.015

Cited by 35 publications

(29 citation statements)

References 32 publications

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“…For very small and very large particles, there is prevalently an agreement with theoretical studies [19,25,38]. However, theoretical parameterizations prevalently underestimate observed  values by one to two orders of magnitude for particles in the 0.1 μm -1 μm radius range and by one order of magnitude for particles smaller than 0.1 m, compared to the available field measurements [79].…”

Section: Below-cloud Scavengingsupporting

confidence: 66%

“…Thus, there is a minimum collection efficiency for particles in the approximate range of 0.1 μm -1 μm, where phoretic and electric effects are felt [14,15,25,[35][36][37][38]. The exact depth, width and position of this minimum depend on the properties of the aerosols and hydrometeors, and on ambient conditions.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…Many theoretical studies on scavenging phenomena do not take into account phoretic forces, either in-cloud [7][8][9][10] or below-cloud [6,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25], while other authors consider also phoretic scavenging mechanisms [26][27][28][29][30][31][32][33][34].…”

Section: Theoretical Modelmentioning

confidence: 99%

See 2 more Smart Citations

A Review of Termo- and Diffusio-Phoresis in the Atmospheric Aerosol Scavenging Process. Part 1: Drop Scavenging

Santachiara¹,

Prodi²,

Belosi³

2012

ACS

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The role of phoretic forces in providing in-cloud and below-cloud scavenging due to falling drop is reviewed by considering published papers dealing with theoretical models, laboratory and field measurements. Theoretical analyses agree that Brownian diffusion appears to dominate drop scavenging of aerosol with radius less than 0.1 μm, and inertial impaction dominates scavenging of aerosol with radius higher than 1 μm. Thus, there is a minimum collection efficiency for particles in the approximate range 0.1 μm -1 μm, where phoretic forces are felt. Generally speaking, published papers report not uniform evaluations of the contribution of thermo-and diffusiophoretic forces. This disagreement is partially due to the different laboratory and field conditions, and different theoretical approaches.

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Section: Below-cloud Scavengingsupporting

confidence: 66%

Section: Theoretical Modelmentioning

confidence: 99%

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A Review of Termo- and Diffusio-Phoresis in the Atmospheric Aerosol Scavenging Process. Part 1: Drop Scavenging

Santachiara¹,

Prodi²,

Belosi³

2012

ACS

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“…The modified version of the CMAQ model can distinguish between rainout and washout processes and ignores the washout process for accumulation-mode aerosols because particles of this size are much less efficiently removed by the collision of precipitating raindrops below clouds [Seinfeld and Pandis, 2006]. Several previous studies have shown that below-cloud scavenging is negligible for accumulation-mode aerosol particles when compared with in-cloud scavenging rates for low and moderate rainfall rates (0.1-10 mm h À1 ) [e.g., Andronache, 2003;Henzing et al, 2006;Berthet et al, 2010], supporting our treatment of the wet deposition process. While the CMAQ model explicitly treats aerosol microphysics, such as condensation and coagulation (i.e., aging processes of BC), the CMAQ model assumes all aerosol species in each of the Aitken, accumulation, and coarse modes are internally mixed and the accumulation-mode aerosols (including BC) are hydrophilic [Byun and Ching, 1999;Binkowski and Roselle, 2003].…”

Section: Model Simulationsmentioning

confidence: 99%

Vertical transport mechanisms of black carbon over East Asia in spring during the A‐FORCE aircraft campaign

Oshima¹,

Koike

Kondo

et al. 2013

JGR Atmospheres

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Mechanisms of vertical transport of black carbon (BC) aerosols and their three‐dimensional transport pathways over East Asia in spring were examined through numerical simulations for the Aerosol Radiative Forcing in East Asia (A‐FORCE) aircraft campaign in March–April 2009 using a modified version of the Community Multiscale Air Quality (CMAQ) modeling system. The simulations reproduced the spatial distributions of mass concentration of BC and its transport efficiency observed by the A‐FORCE campaign reasonably well, including its vertical and latitudinal gradients and dependency on precipitation amount that air parcels experienced during the transport. During the A‐FORCE period, two types of pronounced upward BC mass fluxes from the planetary boundary layer (PBL) to the free troposphere were found over northeastern and inland‐southern China. Over northeastern China, cyclones with modest precipitation were the primary uplifting mechanism of BC. Over inland‐southern China, both cumulus convection and orographic uplifting along the slopes of the Tibetan Plateau played important roles in the upward transport of BC, despite its efficient wet deposition due to a large amount of precipitation supported by an abundant moisture supply by the low‐level southerlies. In addition to the midlatitude (35–45°N) eastward outflow within the PBL (21% BC removal by precipitation during transport), the uplifting of BC over northeastern and inland‐southern China and the subsequent BC transport by the midlatitude lower tropospheric (50% BC removal) and subtropical (25–35°N) midtropospheric westerlies (67% BC removal), respectively, provided the major transport pathways for BC export from continental East Asia to the Pacific.

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“…In atmospheric physics, this problem is known as "inertial impaction" and is relevant for estimating rates in rain formation or wet deposition of aerosols where a falling water drop scavenges smaller cloud droplets or solid pollutants. Studies of such problems often rely on collision efficiencies and, again, mainly formulas from laminar flow conditions are used (Berthet et al 2010). A popular formula is that of Slinn (1974), who proposed a fit of the collision efficiency for the inertial impaction regime.…”

Section: Introductionmentioning

confidence: 99%

Effect of turbulence on collisions of dust particles with planetesimals in protoplanetary disks

Homann

Guillot

Bec

et al. 2016

A&A

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Context. Planetesimals in gaseous protoplanetary disks may grow by collecting dust particles. Hydrodynamical studies show that small particles generally avoid collisions with the planetesimals because they are entrained by the flow around them. This occurs when St, the Stokes number, defined as the ratio of the dust stopping time to the planetesimal crossing time, becomes much smaller than unity. However, these studies have been limited to the laminar case, whereas these disks are believed to be turbulent. Aims. We want to estimate the influence of gas turbulence on the dust-planetesimal collision rate and on the impact speeds. Methods. We used three-dimensional direct numerical simulations of a fixed sphere (planetesimal) facing a laminar and turbulent flow seeded with small inertial particles (dust) subject to a Stokes drag. A no-slip boundary condition on the planetesimal surface is modeled via a penalty method. Results. We find that turbulence can significantly increase the collision rate of dust particles with planetesimals. For a high turbulence case (when the amplitude of turbulent fluctuations is similar to the headwind velocity), we find that the collision probability remains equal to the geometrical rate or even higher for St 0.1, i.e., for dust sizes an order of magnitude smaller than in the laminar case. We derive expressions to calculate impact probabilities as a function of dust and planetesimal size and turbulent intensity.

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Scavenging of aerosol particles by rain in a cloud resolving model

Cited by 35 publications

References 32 publications

A Review of Termo- and Diffusio-Phoresis in the Atmospheric Aerosol Scavenging Process. Part 1: Drop Scavenging

A Review of Termo- and Diffusio-Phoresis in the Atmospheric Aerosol Scavenging Process. Part 1: Drop Scavenging

Vertical transport mechanisms of black carbon over East Asia in spring during the A‐FORCE aircraft campaign

Effect of turbulence on collisions of dust particles with planetesimals in protoplanetary disks

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