Supplementary material to "Long-term observations of cloud condensation nuclei in the Amazon rain forest – Part 2: Variability and characteristic differences under near-pristine, biomass burning, and long-range transport conditions"

Abstract. Size-resolved measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations and hygroscopicity were conducted over a full seasonal cycle at the remote Amazon Tall Tower Observatory (ATTO, March 2014–February 2015). In a preceding companion paper, we presented annually and seasonally averaged data and parametrizations (Part 1; Pöhlker et al., 2016a). In the present study (Part 2), we analyze key features and implications of aerosol and CCN properties for the following characteristic atmospheric conditions: Empirically pristine rain forest (PR) conditions, where no influence of pollution was detectable, as observed during parts of the wet season from March to May. The PR episodes are characterized by a bimodal aerosol size distribution (strong Aitken mode with DAit ≈ 70 nm and NAit ≈ 160 cm−3, weak accumulation mode with Dacc ≈ 160 nm and Nacc≈ 90 cm−3), a chemical composition dominated by organic compounds, and relatively low particle hygroscopicity (κAit≈ 0.12, κacc ≈ 0.18). Long-range-transport (LRT) events, which frequently bring Saharan dust, African biomass smoke, and sea spray aerosols into the Amazon Basin, mostly during February to April. The LRT episodes are characterized by a dominant accumulation mode (DAit ≈ 80 nm, NAit ≈ 120 cm−3 vs. Dacc ≈ 180 nm, Nacc ≈ 310 cm−3), an increased abundance of dust and salt, and relatively high hygroscopicity (κAit≈ 0.18, κacc ≈ 0.35). The coarse mode is also significantly enhanced during these events. Biomass burning (BB) conditions characteristic for the Amazonian dry season from August to November. The BB episodes show a very strong accumulation mode (DAit ≈ 70 nm, NAit ≈ 140 cm−3 vs. Dacc ≈ 170 nm, Nacc ≈ 3400 cm−3), very high organic mass fractions (∼ 90 %), and correspondingly low hygroscopicity (κAit≈ 0.14, κacc ≈ 0.17). Mixed-pollution (MPOL) conditions with a superposition of African and Amazonian aerosol emissions during the dry season. During the MPOL episode presented here as a case study, we observed African aerosols with a broad monomodal distribution (D ≈ 130 nm, NCN,10 ≈ 1300 cm−3), with high sulfate mass fractions (∼ 20 %) from volcanic sources and correspondingly high hygroscopicity (κ< 100 nm ≈ 0.14, κ>100nm≈ 0.22), which were periodically mixed with fresh smoke from nearby fires (D ≈ 110 nm, NCN,10 ≈ 2800 cm−3) with an organic-dominated composition and sharply decreased hygroscopicity (κ<150nm≈ 0.10, κ>150nm≈ 0.20). Insights into the aerosol mixing state are provided by particle hygroscopicity (κ) distribution plots, which indicate largely internal mixing for the PR aerosols (narrow κ distribution) and more external mixing for the BB, LRT, and MPOL aerosols (broad κ distributions). The CCN spectra (CCN concentration plotted against water vapor supersaturation) obtained for the different case studies indicate distinctly different regimes of cloud formation and microphysics depending on aerosol properties and meteorological conditions. The measurement results suggest that CCN activation and droplet formation in convective clouds are mostly aerosol-limited under PR and LRT conditions and updraft-limited under BB and MPOL conditions. Normalized CCN efficiency spectra (CCN divided by aerosol number concentration plotted against water vapor supersaturation) and corresponding parameterizations (Gaussian error function fits) provide a basis for further analysis and model studies of aerosol–cloud interactions in the Amazon.

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Effects of long-range transport and clouds on cloud condensation nuclei in the springtime Arctic

Journal of Geophysical Research Atmospheres ◽

10.1029/2001jd000759 ◽

2002 ◽

Vol 107 (D16) ◽

Cited By ~ 10

Author(s):

Donald P. Wylie

Keyword(s):

Long Range ◽

Cloud Condensation Nuclei ◽

Long Range Transport ◽

Condensation Nuclei ◽

Range Transport

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Long-term measurements of carbonaceous aerosols in the Eastern Mediterranean: evidence of long-range transport of biomass burning

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-5551-2008 ◽

2008 ◽

Vol 8 (18) ◽

pp. 5551-5563 ◽

Cited By ~ 126

Author(s):

J. Sciare ◽

K. Oikonomou ◽

O. Favez ◽

E. Liakakou ◽

Z. Markaki ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Long Range ◽

Biomass Burning ◽

Water Soluble ◽

Long Range Transport ◽

Crete Island ◽

Yearly Average ◽

Range Transport

Abstract. Long-term (5-year) measurements of Elemental Carbon (EC) and Organic Carbon (OC) in bulk aerosols are presented here for the first time in the Mediterranean Basin (Crete Island). A multi-analytical approach (including thermal, optical, and thermo-optical techniques) was applied for these EC and OC measurements. Light absorbing dust aerosols were shown to poorly contribute (+12% on a yearly average) to light absorption coefficient (babs) measurements performed by an optical method (aethalometer). Long-range transport of agricultural waste burning from European countries surrounding the Black Sea was shown for each year during two periods (March–April and July–September). The contribution of biomass burning to the concentrations of EC and OC was shown to be rather small (20 and 14%, respectively, on a yearly basis), although this contribution could be much higher on a monthly basis and showed important seasonal and interannual variability. By removing the biomass burning influence, our data revealed an important seasonal variation of OC, with an increase by almost a factor of two for the spring months of May and June, whereas BC was found to be quite stable throughout the year. Preliminary measurements of Water Soluble Organic Carbon (WSOC) have shown that the monthly mean WSOC/OC ratio remains stable throughout the year (0.45±0.12), suggesting that the partitioning between water soluble and water insoluble organic matter is not significantly affected by biomass burning and secondary organic aerosol (SOA) formation. A chemical mass closure performed in the fine mode (Aerodynamic Diameter, A.D.<1.5μm) showed that the mass contribution of organic matter (POM) was found to be essentially invariable during the year (monthly average of 26±5%).

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Long-term measurements of carbonaceous aerosols in the eastern Mediterranean: evidence of long-range transport of biomass burning

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-6949-2008 ◽

2008 ◽

Vol 8 (2) ◽

pp. 6949-6982 ◽

Cited By ~ 4

Author(s):

J. Sciare ◽

K. Oikonomou ◽

O. Favez ◽

Z. Markaki ◽

E. Liakakou ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Long Range ◽

Biomass Burning ◽

Water Soluble ◽

Long Range Transport ◽

Crete Island ◽

Yearly Average ◽

Range Transport

Abstract. Long-term (5-yr) measurements of Black Carbon (BC) and Organic Carbon (OC) in bulk aerosols are presented here for the first time in the Mediterranean Basin (Crete Island). A multi-analytical approach (including thermal, optical, and thermo-optical techniques) was applied for these BC and OC measurements. Light absorbing dust aerosols have shown to poorly contribute (+17% on a yearly average) to light absorption coefficient (babs) measurements performed by an optical method (aethalometer). Long-range transport of agricultural waste burning from European countries surrounding the Black Sea was shown for each year during two periods (March–April and July–September). The contribution of biomass burning to the concentrations of BC and OC has shown to be rather small (20 and 14%, respectively, on a yearly basis), although this contribution could be much higher on a monthly basis and is expected a high intra and inter annual variability. By removing the biomass burning influence, our data revealed an important seasonal variation of OC, with an increase by almost a factor of two for the Spring months of May and June, whereas BC was found to be quite stable throughout the year. Preliminary measurements of Water Soluble Organic Carbon (WSOC) have shown that the monthly mean WSOC/OC ratio remains stable throughout the year (0.45±0.12), suggesting that the partitioning between water soluble and water insoluble organic matter is not significantly affected by biomass burning and secondary organic aerosol (SOA) formation. A chemical mass closure performed in the fine mode (Aerodynamic Diameter, A.D.<1.5 μm) showed that the mass contribution of organic matter (POM) was found to be essentially invariable during the year (monthly average of 26±5%).

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Effects of continental emissions on cloud condensation nuclei (CCN) activity in the northern South China Sea during summertime 2018

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-9153-2020 ◽

2020 ◽

Vol 20 (15) ◽

pp. 9153-9167 ◽

Cited By ~ 1

Author(s):

Mingfu Cai ◽

Baoling Liang ◽

Qibin Sun ◽

Shengzhen Zhou ◽

Xiaoyang Chen ◽

...

Keyword(s):

Chemical Composition ◽

Long Range ◽

Particle Number ◽

Cloud Condensation Nuclei ◽

Northern South China Sea ◽

Long Range Transport ◽

Marine Atmosphere ◽

Condensation Nuclei ◽

Air Masses ◽

Range Transport

Abstract. Aerosol particles in marine atmosphere have been shown to significantly affect cloud formation, atmospheric optical properties, and climate change. However, high temporally and spatially resolved atmospheric measurements over the sea are currently sparse, limiting our understanding of aerosol properties in marine atmosphere. In this study, a ship-based cruise campaign was conducted over the northern South China Sea (SCS) region during summertime 2018. The chemical composition of non-refractory PM1 (NR-PM1), the particle number size distribution (PNSD), and size-resolved cloud condensation nuclei (CCN) activity were measured by a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) and the combination of a cloud condensation nuclei counter (CCNc) and a scanning mobility particle sizer (SMPS). Overall, aerosol particles exhibited a unimodal distribution centering at 60–80 nm and the chemical composition of the NR-PM1 was dominated by sulfate (∼ 46 %), which likely originated from anthropogenic emissions rather than dimethyl sulfide (DMS) oxidation. Two polluted episodes (P1 and P2) were observed, and both were characterized by high particle number concentrations (NCN) which originated from local emissions and from emissions in inland China via long-range transport. The concentrations of trace gases (i.e., O3, CO, NOx) and particles (NCN and NCCN at ss = 0.34 %) were elevated during P2 at the end of the campaign and decreased with offshore distance, further suggesting important impacts of anthropogenic emissions from the inland Pearl River Delta (PRD) region. Two relatively clean periods (C1 and C2) prior to and after tropical storm Bebinca were classified and the air was affected by air masses from the southwest and from the Indo-Chinese Peninsula, respectively. Chemical composition measurements showed an increase in organic mass fraction during P2 compared to C2; however, no obviously different κ values were obtained from the CCNc measurements, implying that the air masses carried pollutants from local sources during long-range transport. We report an average value of about 0.4 for the aerosol hygroscopicity parameter κ, which falls within the literature values (i.e., 0.2–1.0) for urban and remote marine atmosphere. In addition, our results showed that the CCN fraction (NCCN∕NCN, tot) and the κ values had no clear correlation either with the offshore distance or with concentrations of the particles. Our study highlights dynamical variations in particle properties and the impact of long-range transport from continental China and the Indo-Chinese Peninsula on the northern SCS region during summertime.

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Impact of Long-Range Transport Biomass Burning (BB) Emissions on Cloud Condensation Nuclei (CCN) Activation in Continental Polluted Air of Delhi, India

10.5194/egusphere-egu2020-12744 ◽

2020 ◽

Author(s):

Subha S. Raj ◽

Mira L. Pӧhlker ◽

Thomas Klimach ◽

Jan-David Förster ◽

David Walter ◽

...

Keyword(s):

Chemical Composition ◽

Diurnal Variation ◽

Long Range ◽

Biomass Burning ◽

Mass Fraction ◽

Cloud Condensation Nuclei ◽

Average Concentration ◽

Long Range Transport ◽

Organic Mass ◽

Range Transport

Cloud Condensation Nuclei (CCN) and other aerosol properties were investigated in Delhi, India, from Feb. to Mar. 2018. The high anthropogenic influence on aerosol was studied with size-resolved CCN measurements (supersaturation (S) between 0.13 to 0.66% and selected diameters from 10 to 300 nm). Furthermore the chemical composition (Aerosol Chemical Speciation Monitor and Aethalometer AE33) of the particles was measured. The aerosol number size distribution was derived by size data inversion of Differential Mobility Particle Sizer (DMPS) from size-resolved CCN measurements. Based on multi-year back trajectory (BT) data, a spatial clustering analysis was done for the actual campaign period and two distinct clusters were identified: northwest- west northwest-long range transport (NW-LRT) and south-southeast-east southeast (SE).There was preponderant organic mass fraction (forg) in the aerosols throughout the campaign, with prominent diurnal variation except during the SE period. Pronounced diurnal variation was observed also in black carbon (BC) with an average concentration of 16 &#181;g/m3 during NW-LRT, in contrast to a weak diurnal cycle with lower average concentration of 8 &#181;g/m3 during SE. During the NW-LRT cluster the air masses traversed over agriculture fields with biomass burning (BB) activities identified using the fire radiative power (FRP) observations of Copernicus Atmosphere Monitoring Service (CAMS) Global Fire Assimilation System (GFAS). So it can be speculated that the BB emissions from the fields have contributed to enhanced BC concentrations during this period over Delhi. The remaining period, showing a mixture of local and long-range transported emissions also had a BC concentration higher than SE period when only local/regional emissions were observed. This is an important insight into the air pollution apocalypse in Delhi.The overall average values of critical dry diameter (Dc) for CCN activation varied from 54 &#177; 8 nm at S = 0.66% to 139 &#177; 12 nm at S = 0.13%.The hygroscopicity parameter derived from CCN data (&#1082;CCN) was in the range from 0.1 to 0.9 with an arithmetic mean of 0.27 &#177; 0.10, which is close to that of Beijing, another polluted continental region (0.31 &#177; 0.08, Gunthe et al., 2011). &#1082;CCN also shows good agreement with the hygroscopicity parameter derived from the chemical composition measurements. A linear fit (Gunthe et al., 2009) applied to the relationship between refractory/non-refractory organic mass fraction and &#1082;CCN at S = 0.13%, gives an effective hygroscopicity parameter &#1082;org = 0.17 &#177; 0.09 and &#1082;inorg = 0.80 &#177; 0.09, when extrapolated to forg = 1 and forg = 0, respectively. The presence of externally mixed inactive CCN particles is indicated by an average maximum activated fraction (MAF) of 0.82 &#177; 0.17 at S = 0.13%. The overall average Dc, &#1082;CCN, and MAF did not vary much between NW-LRT and SE periods, although the particle number concentration was higher during NW-LRT. Moreover, high CCN efficiency was observed during NW-LRT, in spite of its enhanced BC concentration, indicating the presence of aged internally mixed aerosols. Further details will be presented.

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First Surface Measurement of Cloud Condensation Nuclei over Kanpur, IGP: Role of Long Range Transport

Aerosol Science and Technology ◽

10.1080/02786826.2012.685113 ◽

2012 ◽

Vol 46 (9) ◽

pp. 973-982 ◽

Cited By ~ 17

Author(s):

V. Patidar ◽

S. N. Tripathi ◽

P. K. Bharti ◽

Tarun Gupta

Keyword(s):

Long Range ◽

Cloud Condensation Nuclei ◽

Surface Measurement ◽

Long Range Transport ◽

Condensation Nuclei ◽

Range Transport

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revision Long-term observations of atmospheric aerosol, cloud condensation nuclei concentration and hygroscopicity in the Amazon rain forest – Part 1: Size-resolved characterization and new model parameterizations for CCN pre-diction

10.5194/acp-2016-519-rc2 ◽

2016 ◽

Author(s):

Anonymous

Keyword(s):

Atmospheric Aerosol ◽

Rain Forest ◽

Cloud Condensation Nuclei ◽

Condensation Nuclei ◽

New Model ◽

Aerosol Cloud ◽

Amazon Rain Forest

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Effects of continental emissions on Cloud Condensation Nuclei (CCN) activity in northern South China Sea during summertime 2018

10.5194/acp-2019-1041 ◽

2020 ◽

Author(s):

Mingfu Cai ◽

Baoling Liang ◽

Qibin Sun ◽

Shengzhen Zhou ◽

Bin Yuan ◽

...

Keyword(s):

Long Range ◽

Particle Number ◽

Cloud Condensation Nuclei ◽

Northern South China Sea ◽

Long Range Transport ◽

Marine Atmosphere ◽

Condensation Nuclei ◽

Air Masses ◽

Range Transport ◽

Local Emissions

Abstract. Aerosol particles in marine atmosphere have been shown to significantly affect cloud formation, atmospheric optical properties, and climate change. However, high temporal and spatial resolved atmospheric measurements over sea are currently sparse, limiting our understanding of aerosol properties in marine atmosphere. In this study, a ship-based cruise campaign was conducted over northern South China Sea (SCS) region (19°37′ N to 22°43′ N, 113°44′ E to 118°12′ E) during summertime 2018. Chemical compositions of the non-refractory PM1 (NR-PM1), particle number size distribution (PNSD) and size-resolved cloud condensation nuclei (CCN) activity (at supersaturation ss = 0.18 %, 0.34 %, and 0.59 %) were measured by a time-of-flight aerosol chemical speciation monitor (ToF-ACSM), and the combination of a cloud condensation nuclei counter (CCNc) and a scanning mobility particle sizer (SMPS), respectively. Overall, aerosol particles exhibited a unimodal distribution (centering at 60∼80 nm) and dominated by sulfate (~46 %) in the NR-PM1, similar to the characteristic of previously-reported background marine aerosols. Two polluted episodes were respectively observed at the beginning (P1, 6th–8th August) and at the end (P2, 25th–26th August) of the campaign and both were characterized by high particle number concentrations (NCN) which were shown to originate from local emissions or pollutants from long range transport. Two relatively clean periods (C1, 9th–10th and C2, 19th–21st August) prior to and after tropical storm Bebinca (11th–15th August) were also classified due to substantial removal of pollutants by strong winds and rainfalls accompanying with the storm. A value of about 0.4 for aerosol hygroscopicity parameter κ measured in this study falls in a range of values (i.e., 0.2–1.0) reported previously for urban atmosphere and for remote marine atmosphere. The concentrations of trace gases (i.e., O3, CO, NOX) and particles (NCN and NCCN at ss = 0.34 %) were elevated at the end of the campaign and decreased with the offshore distance, suggesting important impacts of anthropogenic emissions from the inland Pearl River Delta (PRD) region on the northern SCS. A good correlation between NOX concentration and NCN implies similar sources (e.g., heavy ship, traffic, and biomass burning) for NOx and particles. The results showed that the NCCN/NCN,tot and the κ values obtained from the CCNc measurement (ss = 0.34 %) had no clear correlation either with the offshore distance or with the concentrations of the particles. Back trajectory analysis showed that the air pollutants originated from local emissions and from inland China continent via long range transport during P1 and P2, respectively. In addition, the air was affected by air masses from southwest and from Indo-China Peninsula during the clean C1 and C2 periods respectively. Chemical composition measurements showed an increase of organic mass fraction and no obviously different κ values were obtained from CCN measurements during C2 and P2, implying that the air masses carried pollutants from local sources during long range transport from Indo-China Peninsula and from the inland China continent respectively during the above two periods. Our study highlights dynamical variations of particle properties and the impact of long range transport from the China continent and Indo-China Peninsula on the northern SCS region during summertime.

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