Effects of below-cloud scavenging on the regional aerosol budget in East Asia

Bae, Sung‐Heui; Park, Rokjin J.; Kim, Yong Pyo; Woo, Jung Hun

doi:10.1016/j.atmosenv.2011.08.065

Cited by 31 publications

(29 citation statements)

References 41 publications

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“…Potential factors influence the SE of aerosol by precipitation (mostly the below-cloud SE) include the intensity, frequency and duration of rainfall, the mixing process of rainwater and particles, the size distribution of ambient particles and rain droplets, the rain droplets falling velocity, and the category of precipitation [121,[127][128][129][130][131][132][133][134]. However, such studies are still limited.…”

Section: Scavenging Of Bc By In-cloud or Below-cloud Processesmentioning

confidence: 99%

Recent Advances in Quantifying Wet Scavenging Efficiency of Black Carbon Aerosol

Yang

Lin

et al. 2019

Atmosphere

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Black carbon (BC) aerosol is of great importance not only for its strong potential in heating air and impacts on cloud, but also because of its hazards to human health. Wet deposition is regarded as the main sink of BC, constraining its lifetime and thus its impact on the environment and climate. However, substantial controversial and ambiguous issues in the wet scavenging processes of BC are apparent in current studies. Despite of its significance, there are only a small number of field studies that have investigated the incorporation of BC-containing particles into cloud droplets and influencing factors, in particular, the in-cloud scavenging, because it was simplicitly considered in many studies (as part of total wet scavenging). The mass scavenging efficiencies (MSEs) of BC were observed to be varied over the world, and the influencing factors were attributed to physical and chemical properties (e.g., size and chemical compositions) and meteorological conditions (cloud water content, temperature, etc.). In this review, we summarized the MSEs and potential factors that influence the in-cloud and below-cloud scavenging of BC. In general, MSEs of BC are lower at low-altitude regions (urban, suburban, and rural sites) and increase with the rising altitude, which serves as additional evidence that atmospheric aging plays an important role in the chemical modification of BC. Herein, higher altitude sites are more representative of free-tropospheric conditions, where BC is usually more aged. Despite of increasing knowledge of BC–cloud interaction, there are still challenges that need to be addressed to gain a better understanding of the wet scavenging of BC. We recommend that more comprehensive methods should be further estimated to obtain high time-resolved scavenging efficiency (SE) of BC, and to distinguish the impact of in-cloud and below-cloud scavenging on BC mass concentration, which is expected to be useful for constraining the gap between field observation and modeling simulation results.

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Section: Scavenging Of Bc By In-cloud or Below-cloud Processesmentioning

confidence: 99%

Recent Advances in Quantifying Wet Scavenging Efficiency of Black Carbon Aerosol

Yang

Lin

et al. 2019

Atmosphere

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“…Wet scavenging of aerosols, which we use synonymously with precipitation scavenging or wet removal in this study, is traditionally classified as rainout (also termed in-cloud scavenging) and washout (also termed below-cloud scavenging) [Seinfeld and Pandis, 2006]. Below-cloud wet scavenging involves aerosol particles being collected by falling precipitation particles (rain, snow, graupel, and hail) through Brownian diffusion, directional interception, inertial impaction, thermophoresis, diffusiophoresis, and electrophoresis mechanisms [Bae et al, 2012]. It is important for removal of coarse and very fine particles from the boundary layer but is relatively inefficient for particles in the accumulation mode size range [Andronache, 2003].…”

Section: Introductionmentioning

confidence: 99%

Aerosol transport and wet scavenging in deep convective clouds: A case study and model evaluation using a multiple passive tracer analysis approach

et al. 2015

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Wet scavenging of aerosols by continental deep convective clouds is studied for a supercell storm complex observed over Oklahoma during the Deep Convective Clouds and Chemistry campaign. A new passive-tracer-based transport analysis framework is developed to characterize convective transport using vertical profiles of several passive trace gases. For this case, the analysis estimates that observed passive gas mixing ratios in the upper troposphere convective outflow consist of 47% low level (<3 km) inflow air, 32% entrained midtroposphere air, and 21% upper troposphere air. The new analysis framework is used to estimate aerosol wet scavenging efficiencies. Observations yield high overall scavenging efficiencies of 81% for submicron aerosol mass. Organic, sulfate, and ammonium aerosols have similar wet scavenging efficiencies (80%-84%). The apparent scavenging efficiency for nitrate aerosol is much lower (57%), but the scavenging efficiency for nitrate aerosol plus nitric acid combined (84%) is close to the other species. Scavenging efficiencies for aerosol number are high for larger particles (84% for 0.15-2.5 μm diameter) but are lower for smaller particles (64% for 0.03-0.15 μm). The storm is simulated using the chemistry version of the Weather Research and Forecasting model. Compared to the observation-based analysis, the standard model strongly underestimates aerosol scavenging efficiencies by 32% and 41% in absolute differences for submicron mass and number. Adding a new treatment of secondary activation significantly improves simulated aerosol scavenging, producing wet scavenging efficiencies that are only 7% and 8% lower than observed efficiencies. This finding emphasizes the importance of secondary activation for aerosol wet removal in deep convective storms.

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“…Results indicated the potential benefit of the method of source identification through back trajectories and the strong influence of the atmospheric flow patterns on pollutant dispersion and provided better understanding of sources of air pollution. Bae et al (2012) incorporated a newly developed below-cloud scavenging scheme in the Community Multiscale Air Quality (CMAQ) model to examine the effects of below-cloud scavenging on aerosol concentrations over East Asia during spring 2001. The results from the simulations of wet deposition fluxes of aerosols by the new scheme, show better agreement with observations.…”

Section: Introductionmentioning

confidence: 99%

Examination of in-cloud sulfate chemistry using a different model initialization

Spiridonov

Ćurić

Jakimosvki

2018

Air Qual Atmos Health

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We first examine characteristics of in-cloud sulfate chemistry of a mid-latitude convective cloud using a different model initialization. Specifically, we studied the relative importance of convection on sulfate aerosol transport and redistribution. The analysis is focused on 4 April 2000, when considerable dust transport is evidenced with high concentration and wet deposition of sulfate aerosol measured at the European Monitoring Environmental Program (EMEP) station located in the western mountain part of the Republic of Macedonia. The cloud-resolving model coupled with aqueous sulfate chemistry module has been employed to simulate the sulfate aerosol aqueous chemistry and wet deposition. The modeled results and sensitivities under various initializations are evaluated and compared with a ground-based measurements and laboratory analysis. The results indicate that the local environmental profiles derived from 2.5 km-scale WRF model provides a better cloud model initialization, capable of realistic representation of sub-grid-scale processes which are not adequately resolved by the WRF model with a coarser grid resolution. The method also shows a relatively good performance in simulation of cloud physical processes which take place in-cloud and the near cloud environment, cloud-chemistry interactions, relevant to sulfate acidification and sulfate deposition, which allows a more accurate quantitative assessment of sulfate concentration and pH values. Analysis also indicated that scavenging and oxidation are the principal processes affecting sulfate production, participating with 33 and 46%, respectively. Turning off the ice-phase processes leads to overprediction of sulfate aerosol production for about 8% relative to the base run. The verification analysis indicates that the numerical simulation initialized with a 2.5-km-scale WRF model shows a higher correlation coefficient with observations compared to other runs. This approach of initialization based on WRF conditions provides a scientific contribution by evaluating simulations of convective clouds in Macedonia against ground-based meteorological and chemical data, as well as by using the model to understand the driving processes affecting sulfate production and wet deposition.

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Effects of below-cloud scavenging on the regional aerosol budget in East Asia

Cited by 31 publications

References 41 publications

Recent Advances in Quantifying Wet Scavenging Efficiency of Black Carbon Aerosol

Recent Advances in Quantifying Wet Scavenging Efficiency of Black Carbon Aerosol

Aerosol transport and wet scavenging in deep convective clouds: A case study and model evaluation using a multiple passive tracer analysis approach

Examination of in-cloud sulfate chemistry using a different model initialization

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