Impact of urban aerosol properties on cloud condensation nuclei (CCN) activity during the KORUS-AQ field campaign

Kim, Najin; Park, Minsu; Yum, Seong Soo; Park, Jong Sung; Shin, Hye Jung; Ahn, JaeKyoung

doi:10.1016/j.atmosenv.2018.05.019

Cited by 23 publications

(31 citation statements)

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“…Present study also is in line with the earlier observations reported over various oceanic regions, which depicted higher activation fraction for continental aerosols than clean marine aerosols (Yum et al, 2007). A strong association is observed between GMD and hygroscopicity parameter for different mixing state 10 conditions (external, internal and internal with non-growth) over Korean peninsula (Kim et al, 2018). Present study highlight that the higher activation fractions are observed for the continental or marine aerosols mostly in the absence of ultrafine particle bursts events.…”

Section: Ccn Activation Fraction and Geometric Mean Diametersupporting

confidence: 92%

Cloud Condensation Nuclei properties of South Asian outflow over the northern Indian Ocean during winter

Nair¹,

Jayachandran²,

Kompalli³

et al. 2019

Preprint

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Abstract. Extensive measurements of cloud condensation nuclei (CCN) and condensation nuclei (CN) concentrations in the South Asian outflow to the northern Indian Ocean were carried out on board an instrumented research vessel, as part of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) during winter season (January&#8211;February 2018). Measurements include a north-south transect across the South Asian plume over the northern Indian Ocean and east&#8211;west transect over the equatorial Indian Ocean (~&#8201;2&#176;&#8201;S), which is far away from the continental sources. South Asian outflow over the northern Indian Ocean is characterized by the high values of CCN number concentration (~&#8201;5000&#8201;cm&#8722;3), low CCN activation efficiency (~&#8201;25&#8201;%) and steep increase in CCN concentration with an increase in supersaturation. In contrast, low CCN concentration (~&#8201;1000&#8201;cm&#8722;3) with flat supersaturation spectra was found over the equatorial Indian Ocean. The CCN properties exhibited significant dependence on the geometric mean diameter (GMD) of the aerosol number size distribution and CCN activation efficiency decreased to low values (<&#8201;20&#8201;%) at the times of new particle formation events over near-coastal and remote oceanic regions. The analysis of the activation fractions for the <q>similar</q> aerosol size distributions over the northern Indian Ocean indicated the primary role of aerosol number size distribution, followed by the chemical composition on CCN activation efficiency. The dependence of CCN properties and activation fraction on size segregated aerosol number concentration, especially during the ultrafine particle events, is investigated in detail for the first time over the region.

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Section: Ccn Activation Fraction and Geometric Mean Diametersupporting

confidence: 92%

Cloud Condensation Nuclei properties of South Asian outflow over the northern Indian Ocean during winter

Nair¹,

Jayachandran²,

Kompalli³

et al. 2019

Preprint

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“…AQ measurements 5 (including CO 2 ) from aircrafts, ships, and ground sites were obtained during this period. The campaign was designed to answer three scientific questions, including (1) what are the challenges and opportunities for satellite observations of air quality; (2) what are the factors governing ozone photochemistry and aerosol evolution; (3) how do model performance and needed improvements to better represent atmospheric composition over Korea and its connection to the larger global atmosphere (Kim and Park, 2014, KORUS-AQ White Paper). Fig.…”

Section: Cams Co and Co 2 Forecasts And Analysismentioning

confidence: 99%

“…During May to June 2016, the KORUS-AQ field collected comprehensive measurements of air quality (including CO 2 and tracers of fossil-fuel combustion) over the South Korean peninsula and its surrounding waters. KORUS-AQ is an international collaboration between U.S. and South Korea to better understand the factors controlling air quality in the region across urban, rural, and coastal interfaces (Kim and Park, 2014, KORUS-AQ White Paper). This field campaign follows several NASA-led sub-orbital missions in the past focusing on air quality in the 20…”

mentioning

confidence: 99%

Evaluating High-Resolution Forecasts of Atmospheric CO and CO2 from a Global Prediction System during KORUS-AQ Field Campaign

Tang¹,

Arellano²,

DiGangi³

et al. 2018

Preprint

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Abstract. Accurate and consistent monitoring of anthropogenic combustion is imperative because of its significant health and environmental impacts, especially at city-to-regional scale. Here, we assess the performance of the Copernicus Atmosphere Monitoring Service (CAMS) global prediction system using measurements from aircraft, ground sites, and ships during the Korea United States Air Quality (KORUS-AQ) field study in May to June 2016. Our evaluation focuses on CAMS CO and CO 2 analyses plus two higher resolution forecasts (16-km and 9-km horizontal resolution), to assess their 5 capability in predicting combustion signatures over East Asia. Our results show a slight overestimation of CAMS CO 2 with a mean bias against airborne CO 2 measurements of 2.2, 0.7, and 0.3 ppmv for 16-km and 9-km CO 2 forecasts, and analyses, respectively. The positive CO 2 mean bias in the16-km forecast appears to be consistent across the vertical profile of the measurements. In contrast, we find a moderate underestimation of CAMS CO with an overall bias against airborne CO measurements of -19.2 (16-km), -16.7 (9-km), and -20.7 ppbv (analysis). This negative CO mean bias is mostly seen below 10 750 hPa for all three forecast/analysis configurations. Despite these biases, CAMS show a remarkable agreement with observed enhancement ratios of CO with CO 2 over Seoul metropolitan and over the West Sea, where East Asian outflows were sampled during the study period. More efficient combustion is observed over Seoul (∆CO/∆CO % = 9 ppbv/ppmv) compared to the West Sea (∆CO/∆CO % = 28 ppbv/ppmv). This 'combustion signature contrast' is consistent with previous studies in these two regions. CAMS captured this difference in enhancement ratios (Seoul: 8-12 ppbv/ppmv, West Sea: ~30 15 ppbv/ppmv) regardless of forecast/analysis configurations. The correlation of CAMS CO bias with CO 2 bias is relatively high over these two regions (Seoul: 0.64-0.90, West Sea: ~0.80) suggesting that the contrast captured by CAMS may be dominated by anthropogenic emission ratios used in CAMS. However, CAMS shows poorer performance in terms of capturing local-to-urban CO and CO 2 variability. Along with measurements at ground sites over the Korean peninsula, CAMS produces too high CO and CO 2 concentrations at the surface with steeper vertical gradients (~0.4 ppmv/hPa for CO 2 20 and 3.5 ppbv/hPa for CO) in the morning samples than observed (~0.25 ppmv/hPa for CO 2 and 1.7 ppbv/hPa for CO), suggesting weaker boundary layer mixing in the model. Lastly, we find that the combination of CO analyses (i.e., improved initial condition) and use of finer resolution (9-km vs 16-km) generally produce better forecasts.

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“…We note that it is well-known that a change or difference in CCN concentrations will lead to a smaller change or difference in cloud droplet number concentrations (e.g., [43][44][45]), due in part to supersaturation suppression by increased competition for water vapour. While variation in chemical composition is less important than size in determining CCN concentrations [46,47], heterogeneity in hygroscopicity still significantly affects CCN concentrations [48][49][50], particularly at low supersaturations [47]. If variation in particle composition with size is neglected, then a fully-internally-mixed assumption will frequently overestimate CCN concentrations, particularly at low supersaturations.…”

Section: Impacts On Ccn Concentrationsmentioning

confidence: 99%

A Review of the Representation of Aerosol Mixing State in Atmospheric Models

Stevens

Dastoor

2019

Atmosphere

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Aerosol mixing state significantly affects concentrations of cloud condensation nuclei (CCN), wet removal rates, thermodynamic properties, heterogeneous chemistry, and aerosol optical properties, with implications for human health and climate. Over the last two decades, significant research effort has gone into finding computationally-efficient methods for representing the most important aspects of aerosol mixing state in air pollution, weather prediction, and climate models. In this review, we summarize the interactions between mixing-state and aerosol hygroscopicity, optical properties, equilibrium thermodynamics and heterogeneous chemistry. We focus on the effects of simplified assumptions of aerosol mixing state on CCN concentrations, wet deposition, and aerosol absorption. We also summarize previous approaches for representing aerosol mixing state in atmospheric models, and we make recommendations regarding the representation of aerosol mixing state in future modelling studies.

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Impact of urban aerosol properties on cloud condensation nuclei (CCN) activity during the KORUS-AQ field campaign

Cited by 23 publications

References 50 publications

Cloud Condensation Nuclei properties of South Asian outflow over the northern Indian Ocean during winter

Cloud Condensation Nuclei properties of South Asian outflow over the northern Indian Ocean during winter

Evaluating High-Resolution Forecasts of Atmospheric CO and CO<sub>2</sub> from a Global Prediction System during KORUS-AQ Field Campaign

A Review of the Representation of Aerosol Mixing State in Atmospheric Models

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Impact of urban aerosol properties on cloud condensation nuclei (CCN) activity during the KORUS-AQ field campaign

Cited by 23 publications

References 50 publications

Cloud Condensation Nuclei properties of South Asian outflow over the northern Indian Ocean during winter

Cloud Condensation Nuclei properties of South Asian outflow over the northern Indian Ocean during winter

Evaluating High-Resolution Forecasts of Atmospheric CO and CO&lt;sub&gt;2&lt;/sub&gt; from a Global Prediction System during KORUS-AQ Field Campaign

A Review of the Representation of Aerosol Mixing State in Atmospheric Models

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Evaluating High-Resolution Forecasts of Atmospheric CO and CO<sub>2</sub> from a Global Prediction System during KORUS-AQ Field Campaign