scholarly journals Characterization of aerosol growth events over Ellesmere Island during the summers of 2015 and 2016

2018 ◽  
Author(s):  
Samantha Tremblay ◽  
Jean-Christophe Picard ◽  
Jill O. Bachelder ◽  
Erik Lutsch ◽  
Kimberly Strong ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Particle Growth ◽  
Temperature Inversion ◽  
Nucleation And Growth ◽  
Ellesmere Island ◽  
The Arctic ◽  
Particle Nucleation ◽  
Particle Phase ◽  
Aerosol Composition ◽  
Aerosol Mass

Abstract. The occurrence of frequent aerosol nucleation and growth events in the Arctic during summertime may impact the region’s climate through increasing the number of cloud condensation nuclei in the Arctic atmosphere. Measurements of aerosol size distributions and aerosol composition were taken during the summers of 2015 and 2016 at Eureka and Alert on Ellesmere Island in Nunavut, Canada. The corresponding results provide a better understanding of the frequency and spatial extent of these nucleation and growth events as well as of the composition and sources of aerosol mass during particle growth. These events are observed beginning in June with the melting of the sea ice rather than with polar sunrise, which strongly suggests emissions from marine sources are the primary cause of the events. Frequent particle nucleation followed by growth occurs throughout the summer. Correlated particle growths events at the two sites, separated by 480 km, indicate conditions existing over such large scales play a key role in determining the timing and the characteristics of the events. In addition, aerosol mass spectrometry measurements are used to analyze the size-resolved chemical composition of aerosols during two selected growth events. It is found that particles with diameters smaller than 100 nm are predominately organic with only a small sulphate contribution. The oxidation of the organic fraction also changes with particle size with larger particles containing a greater fraction of organic acids relative to other non-acid oxygenates (e.g. alcohols or aldehydes). It is also observed that the relative amount of m / z 44 in the measured mass spectra increases during the growth events suggesting increases in organic acid concentrations in the particle phase. The nucleation and growth events at Eureka are observed most often when the temperature inversion between the sea and the measurement site (at 610 m a.s.l.) is non-existent or weak allowing presumably fresh marine emissions to be mixed upward to the observatory altitude. While the nature of the gaseous precursors responsible for the growth events are poorly understood, oxidation of dimethyl sulphide alone to produce particle phase sulphate or methanesulphonic acid is not consistent with the measured aerosol composition, suggesting the importance of condensation of other gas phase organic compounds for particle growth.

scholarly journals Characterization of aerosol growth events over Ellesmere Island during the summers of 2015 and 2016

2019 ◽  
Vol 19 (8) ◽  
pp. 5589-5604 ◽  
Author(s):  
Samantha Tremblay ◽  
Jean-Christophe Picard ◽  
Jill O. Bachelder ◽  
Erik Lutsch ◽  
Kimberly Strong ◽  
...  
Keyword(s):  
Dimethyl Sulfide ◽  
Marine Boundary Layer ◽  
Cloud Condensation Nuclei ◽  
Methanesulfonic Acid ◽  
Particle Growth ◽  
Temperature Inversion ◽  
Ellesmere Island ◽  
The Arctic ◽  
Aerosol Composition ◽  
Aerosol Mass

Abstract. The occurrence of frequent aerosol nucleation and growth events in the Arctic during summertime may impact the region's climate through increasing the number of cloud condensation nuclei in the Arctic atmosphere. Measurements of aerosol size distributions and aerosol composition were taken during the summers of 2015 and 2016 at Eureka and Alert on Ellesmere Island in Nunavut, Canada. These results provide a better understanding of the frequency and spatial extent of elevated Aitken mode aerosol concentrations as well as of the composition and sources of aerosol mass during particle growth. Frequent appearances of small particles followed by growth occurred throughout the summer. These particle growth events were observed beginning in June with the melting of the sea ice rather than with the polar sunrise, which strongly suggests that influence from the marine boundary layer was the primary cause of the events. Correlated particle growth events at the two sites, separated by 480 km, indicate conditions existing over large scales play a key role in determining the timing and the characteristics of the events. In addition, aerosol mass spectrometry measurements were used to analyze the size-resolved chemical composition of aerosols during two selected growth events. It was found that particles with diameters between 50 and 80 nm (physical diameter) during these growth events were predominately organic with only a small sulfate contribution. The oxidation of the organics also changed with particle size, with the fraction of organic acids increasing with diameter from 80 to 400 nm. The growth events at Eureka were observed most often when the temperature inversion between the sea and the measurement site (at 610 m a.s.l.) was non-existent or weak, presumably creating conditions with low aerosol condensation sink and allowing fresh marine emissions to be mixed upward to the observatory's altitude. While the nature of the gaseous precursors responsible for the growth events is still poorly understood, oxidation of dimethyl sulfide alone to produce particle-phase sulfate or methanesulfonic acid was inconsistent with the measured aerosol composition, suggesting the importance of other gas-phase organic compounds condensing for particle growth.

scholarly journals Size and composition measurements of background aerosol and new particle growth in a Finnish forest during QUEST 2 using an Aerodyne Aerosol Mass Spectrometer

2005 ◽  
Vol 5 (5) ◽  
pp. 8755-8789 ◽  
Author(s):  
J. D. Allan ◽  
M. R. Alfarra ◽  
K. N. Bower ◽  
H. Coe ◽  
J. T. Jayne ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Particle Growth ◽  
Small Mass ◽  
Oxidation Products ◽  
Particle Nucleation ◽  
Aerosol Mass Spectrometer ◽  
Mass Spectral ◽  
Aerosol Mass

Abstract. The study of the growth of nucleation-mode particles is important, as this prevents their loss through diffusion and allows them to reach sizes where they may become effective cloud condensation nuclei. Hyytiälä, a forested site in southern Finland, frequently experiences particle nucleation events during the spring and autumn, where particles first appear during the morning and continue to grow for several hours afterwards. As part of the QUEST 2 intensive field campaign during March and April 2003, an Aerodyne Aerosol Mass Spectrometer (AMS) was deployed alongside other aerosol instrumentation to study the particulate composition and dynamics of growth events and characterise the background aerosol. Despite the small mass concentrations, the AMS was able to distinguish the grown particles in the <100 nm regime several hours after an event and confirm that the particles were principally organic in composition. The AMS was also able to derive a mass spectral fingerprint for the organic species present, and found that it was consistent between events and independent of the mean particle diameter during non-polluted cases, implying the same species were also condensing onto the accumulation mode. The results were compared with those from offline analyses such as GC-MS and were consistent with the hypothesis that the main components were alkanes from plant waxes and the oxidation products of terpenes.

scholarly journals Size and composition measurements of background aerosol and new particle growth in a Finnish forest during QUEST 2 using an Aerodyne Aerosol Mass Spectrometer

2006 ◽  
Vol 6 (2) ◽  
pp. 315-327 ◽  
Author(s):  
J. D. Allan ◽  
M. R. Alfarra ◽  
K. N. Bower ◽  
H. Coe ◽  
J. T. Jayne ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Particle Growth ◽  
Small Mass ◽  
Oxidation Products ◽  
Particle Nucleation ◽  
Aerosol Mass Spectrometer ◽  
Mass Spectral ◽  
Aerosol Mass

Abstract. The study of the growth of nucleation-mode particles is important, as this prevents their loss through diffusion and allows them to reach sizes where they may become effective cloud condensation nuclei. Hyytiälä, a forested site in southern Finland, frequently experiences particle nucleation events during the spring and autumn, where particles first appear during the morning and continue to grow for several hours afterwards. As part of the QUEST 2 intensive field campaign during March and April 2003, an Aerodyne Aerosol Mass Spectrometer (AMS) was deployed alongside other aerosol instrumentation to study the particulate composition and dynamics of growth events and characterise the background aerosol. Despite the small mass concentrations, the AMS was able to distinguish the grown particles in the <100 nm regime several hours after an event and confirm that the particles were principally organic in composition. The AMS was also able to derive a mass spectral fingerprint for the organic species present, and found that it was consistent between events and independent of the mean particle diameter during non-polluted cases, implying the same species were also condensing onto the accumulation mode. The results were compared with those from offline analyses such as GC-MS and were consistent with the hypothesis that the main components were alkanes from plant waxes and the oxidation products of terpenes.

Arctic fog chemistry induces the unexpected growth of Aitken mode particles to CCN-active particles

2021 ◽  
Author(s):  
Erik H. Hoffmann ◽  
Andreas Tilgner ◽  
Simonas Kecorius ◽  
Hartmut Herrmann
Keyword(s):  
Growth Mechanism ◽  
Marine Boundary Layer ◽  
Cloud Condensation Nuclei ◽  
Methanesulfonic Acid ◽  
Particle Growth ◽  
High Water ◽  
The Arctic ◽  
Radiative Balance ◽  
Active Particles ◽  
Aitken Mode

&lt;p&gt;New particle formation (NPF) and early growth are efficient processes producing high concentrations of cloud condensation nuclei (CCNs) precursors in the Arctic marine boundary layer (AMBL). However, due to short lifetime and lack of condensable vapors, newly formed particles do often not grow beyond 50 nm and cause low CCN particle concentrations in the AMBL. Thus, even the smallest amount of Aitken mode particle growth is capable to significantly increase the CCN budget. However, the growth mechanism of Aitken-mode particles from NPF into CCN range in the Arctic is still rather unclear and was therefore investigated during the cruise campaign PASCAL in 2017.&lt;/p&gt; &lt;p&gt;During PASCAL, aerosol particles measurements were performed and an unexpected rapid growth of Aitken mode particles was observed right after fog episodes. Combined field data analyses and detailed multiphase chemistry box model simulations with the CAPRAM mechanism were performed to study the underlying processes. Resulting, a new mechanism is proposed explaining how particles with d &lt; 50 nm are able to grow into CCN size range in the Arctic without requiring high water vapor supersaturation (SS). The investigations demonstrated that the rapid post-fog particle growth of Aitken mode is related to chemical processes within the Arctic fog. The redistribution of semi-volatile acidic (e.g., methanesulfonic acid) and basic (e.g., ammonia) compounds from processed CCN-active particles to smaller CCN-inactive particles can cause a rapid particle growth of Aitken mode particles after fog evaporation enabling them to grow towards CCN size. Comparisons of the model results with Berner impactor measurements supports the proposed growth mechanism.&lt;/p&gt; &lt;p&gt;Overall, this study provided new insights on how the increasing frequency of NPF and fog-related particle processing can increase in the number of CCNs and cloud droplets leading to an increased albedo of Arctic clouds and thus affect the radiative balance in the Arctic. Since fogs will occur more frequently in the Arctic as a result of climate change, this growth mechanism and a deeper knowledge on its feedbacks can be essential to understand Arctic warming.&lt;/p&gt;

scholarly journals Summertime observations of ultrafine particles and cloud condensation nuclei from the boundary layer to the free troposphere in the Arctic

2016 ◽  
Author(s):  
Julia Burkart ◽  
Megan D. Willis ◽  
Heiko Bozem ◽  
Jennie L. Thomas ◽  
Kathy Law ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ultrafine Particles ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Open Ocean ◽  
The Arctic ◽  
Condensation Nuclei ◽  
Aerosol Composition ◽  
Low Level ◽  
20 Nm

Abstract. The Arctic is extremely sensitive to climate change. Shrinking sea ice extent increases the area covered by open ocean during Arctic summer, which impacts the surface albedo and aerosol and cloud properties among many things. In this context extensive aerosol measurements (aerosol composition, particle number and size, cloud condensation nuclei, and trace gases) were made during 11 flights of the NETCARE July, 2014 airborne campaign conducted from Resolute Bay, Nunavut (74N, 94W). Flights routinely included vertical profiles from about 60 to 3000 m a.g.l. as well as several low-level horizontal transects over open ocean, fast ice, melt ponds, and polynyas. Here we discuss the vertical distribution of ultrafine particles (UFP, particle diameter, dp: 5–20 nm), size distributions of larger particles (dp: 20 nm to 1 μm), and cloud condensation nuclei (CCN, supersaturation = 0.6 %) in relation to meteorological conditions and underlying surfaces. UFPs were observed predominantly within the boundary layer, where concentrations were often several hundreds to a few thousand particles per cubic centimeter. Occasionally, particle concentrations below 10 cm−3 were found. The highest UFP concentrations were observed above open ocean and at the top of low-level clouds, whereas numbers over ice-covered regions were substantially lower. Overall, UFP formation events were frequent in a clean boundary layer with a low condensation sink. In a few cases this ultrafine mode extended to sizes larger than 40 nm, suggesting that these UFP can grow into a size range where they can impact clouds and therefore climate.

scholarly journals Cloud condensation nuclei closure study on summer arctic aerosol

2011 ◽  
Vol 11 (22) ◽  
pp. 11335-11350 ◽  
Author(s):  
M. Martin ◽  
R. Y.-W. Chang ◽  
B. Sierau ◽  
S. Sjogren ◽  
E. Swietlicki ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
The Arctic ◽  
Mass Composition ◽  
Organic Mass ◽  
Condensation Nuclei ◽  
Differential Mobility ◽  
Aerosol Mass ◽  
Arctic Aerosol

Abstract. We present an aerosol – cloud condensation nuclei (CCN) closure study on summer high Arctic aerosol based on measurements that were carried out in 2008 during the Arctic Summer Cloud Ocean Study (ASCOS) on board the Swedish ice breaker Oden. The data presented here were collected during a three-week time period in the pack ice (>85° N) when the icebreaker Oden was moored to an ice floe and drifted passively during the most biological active period into autumn freeze up conditions. CCN number concentrations were obtained using two CCN counters measuring at different supersaturations. The directly measured CCN number concentration was then compared with a CCN number concentration calculated using both bulk aerosol mass composition data from an aerosol mass spectrometer (AMS) and aerosol number size distributions obtained from a differential mobility particle sizer, assuming κ-Köhler theory, surface tension of water and an internally mixed aerosol. The last assumption was supported by measurements made with a hygroscopic tandem differential mobility analyzer (HTDMA) for particles >70 nm. For the two highest measured supersaturations, 0.73 and 0.41%, closure could not be achieved with the investigated settings concerning hygroscopicity and density. The calculated CCN number concentration was always higher than the measured one for those two supersaturations. This might be caused by a relative larger insoluble organic mass fraction of the smaller particles that activate at these supersaturations, which are thus less good CCN than the larger particles. On average, 36% of the mass measured with the AMS was organic mass. At 0.20, 0.15 and 0.10% supersaturation, closure could be achieved with different combinations of hygroscopic parameters and densities within the uncertainty range of the fit. The best agreement of the calculated CCN number concentration with the observed one was achieved when the organic fraction of the aerosol was treated as nearly water insoluble (κorg=0.02), leading to a mean total κ, κtot, of 0.33 ± 0.13. However, several settings led to closure and κorg=0.2 is found to be an upper limit at 0.1% supersaturation. κorg≤0.2 leads to a κtot range of 0.33 ± 013 to 0.50 ± 0.11. Thus, the organic material ranges from being sparingly soluble to effectively insoluble. These results suggest that an increase in organic mass fraction in particles of a certain size would lead to a suppression of the Arctic CCN activity.

scholarly journals Aerosol size distributions during the Atmospheric Tomography Mission (ATom): methods, uncertainties, and data products

2019 ◽  
Vol 12 (6) ◽  
pp. 3081-3099 ◽  
Author(s):  
Charles A. Brock ◽  
Christina Williamson ◽  
Agnieszka Kupc ◽  
Karl D. Froyd ◽  
Frank Erdesz ◽  
...  
Keyword(s):  
High Resolution ◽  
Size Distribution ◽  
Atmospheric Composition ◽  
The Arctic ◽  
Distribution Data ◽  
Size Distributions ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Data Products

Abstract. From 2016 to 2018 a DC-8 aircraft operated by the US National Aeronautics and Space Administration (NASA) made four series of flights, profiling the atmosphere from 180 m to ∼12 km above sea level (km a.s.l.) from the Arctic to the Antarctic over both the Pacific and Atlantic oceans. This program, the Atmospheric Tomography Mission (ATom), sought to sample the troposphere in a representative manner, making measurements of atmospheric composition in each season. This paper describes the aerosol microphysical measurements and derived quantities obtained during this mission. Dry size distributions from 2.7 nm to 4.8 µm in diameter were measured in situ at 1 Hz using a battery of instruments: 10 condensation particle counters with different nucleation diameters, two ultra-high-sensitivity aerosol size spectrometers (UHSASs), one of which measured particles surviving heating to 300 ∘C, and a laser aerosol spectrometer (LAS). The dry aerosol measurements were complemented by size distribution measurements from 0.5 to 930 µm diameter at near-ambient conditions using a cloud, aerosol, and precipitation spectrometer (CAPS) mounted under the wing of the DC-8. Dry aerosol number, surface area, and volume, and optical scattering and asymmetry parameters at several wavelengths from the near-UV to the near-IR ranges were calculated from the measured dry size distributions (2.7 nm to 4.8 µm). Dry aerosol mass was estimated by combining the size distribution data with particle density estimated from independent measurements of aerosol composition with a high-resolution aerosol mass spectrometer and a single-particle soot photometer. We describe the instrumentation and fully document the aircraft inlet and flow distribution system, the derivation of uncertainties, and the calculation of data products from combined size distributions. Comparisons between the instruments and direct measurements of some aerosol properties confirm that in-flight performance was consistent with calibrations and within stated uncertainties for the two deployments analyzed. The unique ATom dataset contains accurate, precise, high-resolution in situ measurements of dry aerosol size distributions, and integral parameters, and estimates and measurements of optical properties, for particles < 4.8 µm in diameter that can be used to evaluate aerosol abundance and processes in global models.

scholarly journals Characterization of a large biogenic secondary organic aerosol event from eastern Canadian forests

2010 ◽  
Vol 10 (6) ◽  
pp. 2825-2845 ◽  
Author(s):  
J. G. Slowik ◽  
C. Stroud ◽  
J. W. Bottenheim ◽  
P. C. Brickell ◽  
R. Y.-W. Chang ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Transport Model ◽  
Cloud Condensation Nuclei ◽  
Coniferous Forest ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Chemical Transport Model ◽  
Aerosol Composition ◽  
Aerosol Mass

Abstract. Measurements of aerosol composition, volatile organic compounds, and CO are used to determine biogenic secondary organic aerosol (SOA) concentrations at a rural site 70 km north of Toronto. These biogenic SOA levels are many times higher than past observations and occur during a period of increasing temperatures and outflow from Northern Ontario and Quebec forests in early summer. A regional chemical transport model approximately predicts the event timing and accurately predicts the aerosol loading, identifying the precursors as monoterpene emissions from the coniferous forest. The agreement between the measured and modeled biogenic aerosol concentrations contrasts with model underpredictions for polluted regions. Correlations of the oxygenated organic aerosol mass with tracers such as CO support a secondary aerosol source and distinguish biogenic, pollution, and biomass burning periods during the field campaign. Using the Master Chemical Mechanism, it is shown that the levels of CO observed during the biogenic event are consistent with a photochemical source arising from monoterpene oxidation. The biogenic aerosol mass correlates with satellite measurements of regional aerosol optical depth, indicating that the event extends across the eastern Canadian forest. This regional event correlates with increased temperatures, indicating that temperature-dependent forest emissions can significantly affect climate through enhanced direct optical scattering and higher cloud condensation nuclei numbers.

scholarly journals Size-resolved aerosol composition and link to hygroscopicity at a forested site in Colorado

2013 ◽  
Vol 13 (9) ◽  
pp. 23817-23843 ◽  
Author(s):  
E. J. T. Levin ◽  
A. J. Prenni ◽  
B. Palm ◽  
D. Day ◽  
P. Campuzano-Jost ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Large Mass ◽  
Aerosol Composition ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Mass Fractions ◽  
Aerosol Hygroscopicity ◽  
Aerosol Chemical Composition

Abstract. Aerosol hygroscopicity describes the ability of a particle to take up water and form a cloud droplet. Modeling studies have shown sensitivity of precipitation-producing cloud systems to the availability of aerosol particles capable of serving as cloud condensation nuclei (CCN), and hygroscopicity is a key parameter controlling the number of available CCN. Continental aerosol is typically assumed to have a representative hygroscopicity parameter, κ, of 0.3; however, in remote locations this value can be lower due to relatively large mass fractions of organic components. To further our understanding of aerosol properties in remote areas, we measured size-resolved aerosol chemical composition and hygroscopicity in a forested, mountainous site in Colorado during the six-week BEACHON-RoMBAS campaign. This campaign followed a year-long measurement period at this site, and results from the intensive campaign shed light on the previously reported seasonal cycle in aerosol hygroscopicity. New particle formation events were observed routinely at this site and nucleation mode composition measurements indicated that the newly formed particles were predominantly organic. These events likely contribute to the dominance of organic species at smaller sizes, where aerosol organic mass fractions of non-refractory components were between 70–90%. Corresponding aerosol hygroscopicity was observed to range from κ = 0.15–0.22, with hygroscopicity increasing with particle size. Aerosol chemical composition measured by an Aerosol Mass Spectrometer and calculated from hygroscopicity measurements agreed very well during the intensive study with an assumed value of κorg = 0.13 resulting in the best agreement.

scholarly journals Cloud condensation nuclei closure study on summer arctic aerosol

2011 ◽  
Vol 11 (3) ◽  
pp. 8801-8840
Author(s):  
M. Martin ◽  
R. Y.-W. Chang ◽  
B. Sierau ◽  
S. Sjogren ◽  
E. Swietlicki ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
High Arctic ◽  
Number Concentration ◽  
The Arctic ◽  
Mass Composition ◽  
Condensation Nuclei ◽  
Aerosol Mass ◽  
Arctic Aerosol ◽  
Kohler Theory ◽  
Ocean Study

Abstract. We present an aerosol – cloud condensation nuclei CCN) closure study on summer high Arctic aerosol based on measurements that were carried out in summer 2008 during the Arctic Summer Cloud Ocean Study (ASCOS) on board the Swedish ice breaker Oden. The data presented here were collected during a three-week time period in the pack ice (>85° N) when the icebreaker Oden was moored to an ice floe and drifted passively during the most biological active period into autumn freeze up conditions. CCN number concentrations were obtained using two CCN counters measuring at different supersaturations. The directly measured CCN number concentration is then compared with a CCN number concentration calculated using both bulk aerosol mass composition data from an aerosol mass spectrometer and aerosol number size distributions obtained from a differential mobility particle sizer, assuming κ-Köhler theory and an internally mixed aerosol. For the two highest measured supersaturations, 0.73 and 0.41%, closure could not be achieved with the investigated settings concerning hygroscopicity and density. The calculated CCN number concentration was always higher than the measured one. One possible explanation is that the smaller particles that activate at these supersaturations have a relative larger insoluble organic mass fraction and thus are less good CCN than the larger particles. At 0.20, 0.15 and 0.10% supersaturation, the measured CCN number can be represented with different parameters for the hygroscopicity and density of the particles. For the best agreement of the calculated CCNnumber concentration with the measured one the organic fraction of the aerosol needs to be nearly insoluble (қorg=0.02). However, this is not unambigious and қorg=0.2 is found as an upper limit at 0.1% supersaturation.

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