scholarly journals Marine organic matter in the remote environment of the Cape Verde islands – an introduction and overview to the MarParCloud campaign

2020 ◽  
Vol 20 (11) ◽  
pp. 6921-6951 ◽  
Author(s):  
Manuela van Pinxteren ◽  
Khanneh Wadinga Fomba ◽  
Nadja Triesch ◽  
Christian Stolle ◽  
Oliver Wurl ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Organic Matter ◽  
Organic Compounds ◽  
Particle Number ◽  
Aerosol Particles ◽  
Cloud Water ◽  
Cape Verde ◽  
Marine Aerosol ◽  
Biological Production ◽  
Marine Organic Matter

Abstract. The project MarParCloud (Marine biological production, organic aerosol Particles and marine Clouds: a process chain) aims to improve our understanding of the genesis, modification and impact of marine organic matter (OM) from its biological production, to its export to marine aerosol particles and, finally, to its ability to act as ice-nucleating particles (INPs) and cloud condensation nuclei (CCN). A field campaign at the Cape Verde Atmospheric Observatory (CVAO) in the tropics in September–October 2017 formed the core of this project that was jointly performed with the project MARSU (MARine atmospheric Science Unravelled). A suite of chemical, physical, biological and meteorological techniques was applied, and comprehensive measurements of bulk water, the sea surface microlayer (SML), cloud water and ambient aerosol particles collected at a ground-based and a mountain station took place. Key variables comprised the chemical characterization of the atmospherically relevant OM components in the ocean and the atmosphere as well as measurements of INPs and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analyzed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back-trajectory analysis, vertical atmospheric profile analysis, cloud observations and pigment measurements in seawater. Additional modeling studies supported the experimental analysis. During the campaign, the CVAO exhibited marine air masses with low and partly moderate dust influences. The marine boundary layer was well mixed as indicated by an almost uniform particle number size distribution within the boundary layer. Lipid biomarkers were present in the aerosol particles in typical concentrations of marine background conditions. Accumulation- and coarse-mode particles served as CCN and were efficiently transferred to the cloud water. The ascent of ocean-derived compounds, such as sea salt and sugar-like compounds, to the cloud level, as derived from chemical analysis and atmospheric transfer modeling results, denotes an influence of marine emissions on cloud formation. Organic nitrogen compounds (free amino acids) were enriched by several orders of magnitude in submicron aerosol particles and in cloud water compared to seawater. However, INP measurements also indicated a significant contribution of other non-marine sources to the local INP concentration, as (biologically active) INPs were mainly present in supermicron aerosol particles that are not suggested to undergo strong enrichment during ocean–atmosphere transfer. In addition, the number of CCN at the supersaturation of 0.30 % was about 2.5 times higher during dust periods compared to marine periods. Lipids, sugar-like compounds, UV-absorbing (UV: ultraviolet) humic-like substances and low-molecular-weight neutral components were important organic compounds in the seawater, and highly surface-active lipids were enriched within the SML. The selective enrichment of specific organic compounds in the SML needs to be studied in further detail and implemented in an OM source function for emission modeling to better understand transfer patterns, the mechanisms of marine OM transformation in the atmosphere and the role of additional sources. In summary, when looking at particulate mass, we see oceanic compounds transferred to the atmospheric aerosol and to the cloud level, while from a perspective of particle number concentrations, sea spray aerosol (i.e., primary marine aerosol) contributions to both CCN and INPs are rather limited.

scholarly journals Marine organic matter in the remote environment of the Cape Verde Islands – An introduction and overview to the MarParCloud campaign

2019 ◽  
Author(s):  
Manuela van Pinxteren ◽  
Khanneh Wadinga Fomba ◽  
Nadja Triesch ◽  
Christian Stolle ◽  
Oliver Wurl ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Organic Matter ◽  
Organic Compounds ◽  
Particle Number ◽  
Aerosol Particles ◽  
Cloud Water ◽  
Cape Verde ◽  
Biological Production ◽  
Marine Organic Matter ◽  
Cell Counts

Abstract. The project MarParCloud (Marine biological production, organic aerosol Particles and marine Clouds: a process chain) aims at improving our understanding of the genesis, modification and impact of marine organic matter (OM), from its biological production, via its export to marine aerosol particles and, finally, towards its ability to act as ice nucleating particles (INP) and cloud condensation nuclei (CCN). A field campaign at the Cape Verde Atmospheric Observatory (CVAO) in the tropics in September/October 2017 formed the core of this project that was jointly performed with the project (MARine atmospheric Science Unravelled). A suite of chemical, physical, biological and meteorological techniques was applied and comprehensive measurements of bulk water, the sea surface microlayer (SML), cloud water and ambient aerosol particles collected at a ground-based and a mountain station took place. Key variables comprised the chemical characterization of the atmospherically relevant OM components in the ocean and the atmosphere as well as measurements of INP and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analysed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back trajectory analysis, vertical atmospheric profile analysis, cloud observations and pigment measurements in seawater. Additional modelling studies supported the experimental analysis. During the campaign, the CVAO exhibited marine air masses with low and partly moderate dust influences. The marine boundary layer was well mixed as indicated by an almost uniform particle number size distribution within the boundary layer. Lipid biomarkers were present in the aerosol particles in typical concentrations of marine background conditions. Accumulation and coarse mode particles served as CCN and were efficiently transferred to the cloud water. The ascent of ocean-derived compounds, such as sea salt and sugar-like compounds, to the cloud level as derived from chemical analysis and atmospheric transfer modelling results denote an influence of marine emissions on cloud formation. However, INP measurements indicated also a significant contribution of other non-marine sources to the local INP concentration or strong enrichment processes during upward transport. Lipids, sugar-like compounds, UV absorbing humic-like substances and low molecular weight neutral components were important organic compounds in the seawater and highly surface-active lipids were enriched within the SML. The selective enrichment of specific organic compounds in the SML needs to be studied in further detail and implemented in an OM source function for emission modelling to better understand transfer patterns, mechanisms of marine OM transformation in the atmosphere and the role of additional sources. In summary, when looking at particulate mass, we do see oceanic compounds transferred to the atmospheric aerosol and to the cloud level, while from a perspective of particle number concentrations, marine contributions to both CCN and INP are rather limited.

scholarly journals Marine organic matter in the remote environment of the Cape Verde Islands – An introduction and overview to the MarParCloud campaign

2020 ◽  
Author(s):  
Manuela van Pinxteren ◽  
Khanneh Wadinga Fomba ◽  
Nadja Triesch ◽  
Heike Wex ◽  
Xianda Gong ◽  
...  
Keyword(s):  
Organic Matter ◽  
Aerosol Particles ◽  
Cloud Water ◽  
Cape Verde ◽  
Back Trajectory ◽  
Surface Microlayer ◽  
Mercury Species ◽  
Biological Production ◽  
Cell Counts ◽  
Sea Surface Microlayer

<p>The project MarParCloud (marine biological production, organic aerosol particles and marine clouds: a process chain) aims at achieving a better understanding of the biological production of organic matter (OM)in the oceans, its export into marine aerosol particles and finally its ability to act as ice and cloud condensation nuclei (INP and CCN). The core of MarParCloud comprised a field campaign at the Cape Verde Atmosphere Observatory (CVAO) in autumn 2017, where a variety of chemical, physical, biological and meteorological approaches were applied. The investigations included concerted measurements of the bulk water, the Sea Surface Microlayer (SML), ambient aerosol particles on the ground (30 m a.s.l.) and in mountain heights (744 m) as well as cloud water. Important aspects of the ocean atmosphere Interactions focusing on marine OM have been addressed through detailed observation and modeling approaches.</p><p>Key variables comprised the chemical characterization of the atmospherically relevant OM components (e.g. lipids, proteins, sugars) in the ocean and the atmosphere as well as measurements of INP and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analysed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back trajectory analysis, vertical atmospheric profile analysis, cloud observations and pigment measurements in seawater. Additional modelling studies supported the experimental analysis.</p><p>Here we show the proof of concept of the connection between organic matter emission from the ocean to the atmosphere and up to the cloud level. A link between the ocean and the atmosphere was clearly observed as (i) the particles measured at the surface are well mixed within the marine boundary layer up to cloud level and (ii) ocean-derived compounds can be found in the aerosol particles at mountain height and in the cloud water. The organic measurements will be implemented in a new source function for the oceanic emission of OM. However, from a perspective of particle number concentrations, the marine contributions to both CCN and INP are rather limited.</p>

scholarly journals Origin of aerosol particles in the mid-latitude and subtropical upper troposphere and lowermost stratosphere from cluster analysis of CARIBIC data

2009 ◽  
Vol 9 (21) ◽  
pp. 8413-8430 ◽  
Author(s):  
M. Köppe ◽  
M. Hermann ◽  
C. A. M. Brenninkmeijer ◽  
J. Heintzenberg ◽  
H. Schlager ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Cluster Analysis ◽  
Particle Number ◽  
Aerosol Particles ◽  
Free Troposphere ◽  
Data Set ◽  
Upper Troposphere ◽  
Eurasian Continent ◽  
Aitken Mode ◽  
Seasonal Data

Abstract. The origin of aerosol particles in the upper troposphere and lowermost stratosphere over the Eurasian continent was investigated by applying cluster analysis methods to in situ measured data. Number concentrations of submicrometer aerosol particles and trace gas mixing ratios derived by the CARIBIC (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container) measurement system on flights between Germany and South-East Asia were used for this analysis. Four cluster analysis methods were applied to a test data set and their capability of separating the data points into scientifically reasonable clusters was assessed. The best method was applied to seasonal data subsets for summer and winter resulting in five cluster or air mass types: stratosphere, tropopause, free troposphere, high clouds, and boundary layer influenced. Other source clusters, like aircraft emissions could not be resolved in the present data set with the used methods. While the cluster separation works satisfactory well for the summer data, in winter interpretation is more difficult, which is attributed to either different vertical transport pathways or different chemical lifetimes in both seasons. The geographical distribution of the clusters together with histograms for nucleation and Aitken mode particles within each cluster are presented. Aitken mode particle number concentrations show a clear vertical gradient with the lowest values in the lowermost stratosphere (750–2820 particles/cm3 STP, minimum of the two 25% – and maximum of the two 75%-percentiles of both seasons) and the highest values for the boundary-layer-influenced air (4290–22 760 particles/cm3 STP). Nucleation mode particles are also highest in the boundary-layer-influenced air (1260–29 500 particles/cm3 STP), but are lowest in the free troposphere (0–450 particles/cm3 STP). The given submicrometer particle number concentrations represent the first large-scale seasonal data sets for the upper troposphere and lowermost stratosphere over the Eurasian continent.

scholarly journals Origin of aerosol particles in the mid latitude and subtropical upper troposphere and lowermost stratosphere from cluster analysis of CARIBIC data

2009 ◽  
Vol 9 (3) ◽  
pp. 13523-13567 ◽  
Author(s):  
M. Köppe ◽  
M. Hermann ◽  
C. A. M. Brenninkmeijer ◽  
J. Heintzenberg ◽  
H. Schlager ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Cluster Analysis ◽  
Particle Number ◽  
Aerosol Particles ◽  
Free Troposphere ◽  
Data Set ◽  
Upper Troposphere ◽  
Eurasian Continent ◽  
Analysis Methods ◽  
Aitken Mode

Abstract. The origin of aerosol particles in the upper troposphere and lowermost stratosphere over the Eurasian continent was investigated by applying cluster analysis methods to in situ measured data. Number concentrations of submicrometer aerosol particles and trace gas mixing ratios derived by the CARIBIC (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container) measurement system on flights between Germany and South-East Asia were used for this analysis. Four cluster analysis methods were applied to a test data set and their capability of separating the data points into scientifically reasonable clusters was assessed. The best method was applied to seasonal data subsets for summer and winter resulting in five cluster or air mass types: stratosphere, tropopause, free troposphere, high clouds, and boundary layer influenced. Other source clusters, like aircraft emissions could not be resolved in the present data set with the used methods. While the cluster separation works satisfactory well for the summer data, in winter interpretation is more difficult, which is attributed to either different vertical transport pathways or different chemical lifetimes in the two seasons. The geographical distribution of the clusters together with histograms for nucleation and Aitken mode particles within each cluster are presented. Aitken mode particle number concentrations show a clear vertical gradient with the lowest values in the lowermost stratosphere (750–2820 particles/cm3 STP, minimum of the two 25%- and maximum of the two 75%-percentiles of both seasons) and the highest values for the boundary-layer-influenced air (4290–22 760 particles/cm3 STP). Nucleation mode particles are also highest in the boundary-layer-influenced air (1260–29 500 particles/cm3 STP, but are lowest in the free troposphere (0–450 particles/cm3 STP). The given submicrometer particle number concentrations represent the first statistically sound data set for the upper troposphere and lowermost stratosphere over the Eurasian continent.

scholarly journals Characterization of aerosol particles at Cabo Verde close to sea level and at the cloud level – Part 1: Particle number size distribution, cloud condensation nuclei and their origins

2020 ◽  
Vol 20 (3) ◽  
pp. 1431-1449 ◽  
Author(s):  
Xianda Gong ◽  
Heike Wex ◽  
Jens Voigtländer ◽  
Khanneh Wadinga Fomba ◽  
Kay Weinhold ◽  
...  
Keyword(s):  
Size Distribution ◽  
Sea Level ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Number Concentration ◽  
Cape Verde ◽  
Sea Spray ◽  
Particle Number Concentration ◽  
Air Masses

Abstract. In the framework of the MarParCloud (Marine biological production, organic aerosol particles and marine clouds: a Process Chain) project, measurements were carried out on the islands of Cabo Verde (a.k.a. Cape Verde) to investigate the abundance, properties and sources of aerosol particles in general, and cloud condensation nuclei (CCN) in particular, both close to sea level and at the cloud level. A thorough comparison of particle number concentration (PNC), particle number size distribution (PNSD) and CCN number concentration (NCCN) at the Cape Verde Atmospheric Observatory (CVAO, sea-level station) and Monte Verde (MV, cloud-level station) reveals that during times without clouds the aerosols at CVAO and MV are similar and the boundary layer is generally well mixed. Therefore, data obtained at CVAO can be used to describe the aerosol particles at cloud level. Cloud events were observed at MV during roughly 58 % of the time, and during these events a large fraction of particles was activated to cloud droplets. A trimodal parameterization method was deployed to characterize PNC at CVAO. Based on number concentrations in different aerosol modes, four well-separable types of PNSDs were found, which were named the marine type, mixture type, dust type1 and dust type2. Aerosol particles differ depending on their origins. When the air masses came from the Atlantic Ocean, sea spray can be assumed to be one source for particles besides new particle formation. For these air masses, PNSDs featured the lowest number concentration in Aitken, accumulation and coarse modes. Particle number concentrations for sea spray aerosol (SSA, i.e., the coarse mode for these air masses) accounted for about 3.7 % of NCCN,0.30 % (CCN number concentration at 0.30 % supersaturation) and about 1.1 % to 4.4 % of Ntotal (total particle number concentration). When the air masses came from the Sahara, we observed enhanced Aitken, accumulation and coarse mode particle number concentrations and overall increased NCCN; NCCN,0.30 % during the strongest observed dust periods is about 2.5 times higher than that during marine periods. However, the particle hygroscopicity parameter κ for these two most different periods shows no significant difference and is generally similar, independent of air mass. Overall, κ averaged 0.28, suggesting the presence of organic material in particles. This is consistent with previous model work and field measurements. There is a slight increase in κ with increasing particle size, indicating the addition of soluble, likely inorganic, material during cloud processing.

scholarly journals Characterization of aerosol particles at Cape Verde close to sea and cloud level heights – Part 1: particle number size distribution, cloud condensation nuclei and their origins

2019 ◽  
Author(s):  
Xianda Gong ◽  
Heike Wex ◽  
Jens Voigtländer ◽  
Khanneh Wadinga Fomba ◽  
Kay Weinhold ◽  
...  
Keyword(s):  
Size Distribution ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Number Concentration ◽  
Cape Verde ◽  
Sea Spray ◽  
Particle Number Concentration ◽  
Air Masses ◽  
Coarse Mode

Abstract. In the framework of the MarParCloud (Marine biological production, organic aerosol particles and marine clouds: a Process Chain) project, measurements were carried out on the islands of Cape Verde, to investigate the abundance, properties, and sources of aerosol particles in general and cloud condensation nuclei (CCN) in particular, both close to sea and cloud level heights. A thorough comparison of particle number concentration (PNC), particle number size distribution (PNSD) and CCN number concentration (NCCN) at the Cape Verde Atmospheric Observatory (CVAO, sea level station) and Monte Verde (MV, cloud level station) reveals that during times without clouds the aerosol at CVAO and MV are similar and the boundary layer is generally well mixed. Therefore, data obtained at CVAO can be used to describe the aerosol particles at cloud level. Cloud events were observed at MV during roughly 58 % of the time and during these, a large fraction of particles were activated to cloud droplets. A trimodal parameterization method was deployed to characterize PNC at CVAO. Based on number concentrations in different aerosol modes, four well separable types of PNSDs were found, which were named the marine type, mixture type, dust type1 and dust type2. Aerosol particles differ depending on their origins. When the air masses came from the Atlantic Ocean, sea spray can be assumed to be one source for particles, besides for new particle formation. For these air masses, PNSDs featured the lowest number concentration in Aitken, accumulation and coarse mode. Particle number concentrations for the sea spray aerosol (SSA, i.e., the coarse mode for these air masses) accounted for about 3.7 % of NCCN,0.30 % (CCN number concentration at 0.30 % supersaturation) and about 1.1 % to 4.4 % of Ntotal (total particle number concentration). When the air masses came from the Saharan desert, we observed enhanced Aitken, accumulation and coarse mode particle number concentrations and overall increased NCCN. NCCN,0.30 % during the strongest observed dust periods is about 2.5 times higher than that during marine periods. However, the particle hygroscopicity parameter κ for these two most different periods shows no significant difference and is generally similar, independent of air mass. Overall, κ averaged 0.28, suggesting the presence of organic material in particles. This is consistent with previous model work and field measurement. There is a slight increase of κ with increasing particle size, indicating the addition of soluble, likely inorganic material during cloud processing.

scholarly journals Concerted measurements of free amino acids at the Cape Verde Islands: High enrichments in submicron sea spray aerosol particles and cloud droplets

2020 ◽  
Author(s):  
Nadja Triesch ◽  
Manuela van Pinxteren ◽  
Anja Engel ◽  
Hartmut Herrmann
Keyword(s):  
Amino Acids ◽  
Organic Carbon ◽  
Aspartic Acid ◽  
Water Samples ◽  
Free Amino Acids ◽  
Free Amino ◽  
Aerosol Particles ◽  
Cloud Water ◽  
Cape Verde ◽  
Atmospheric Concentration

Abstract. This study presents measurements of free amino acids (FAA) in the marine environment to elucidate their transfer from the ocean into the atmosphere to marine aerosol particles and to clouds. FAA were investigated in seawater (underline water (ULW), sea surface microlayer (SML)), in ambient marine size-segregated aerosol particle samples at two heights (ground based at the Cape Verde Atmospheric Observatory (CVAO) and at the Mt. Verde, 744 m height) and in cloud water using concerted measurements. The ∑FAA concentration in the SML varied between 0.13–3.64 µmol L−1, in the ULW between 0.01–1.10 µmol L−1 and a strong enrichment of ∑FAA in the SML (EFSML: 1.1–298.4, average of 57.2) was observed. In the submicron (0.05–1.2 µm) aerosol particles at the CVAO, the composition of FAA was more complex and higher atmospheric concentration of ∑FAA (up to 6.3 ng m−3) compared to the supermicron (1.2–10 µm) aerosol particles (maxima of 0.5 ng m−3) were observed. The total ∑FAA concentration (PM10) was between 1.8–6.8 ng m−3 and tended to increase during the campaign. Averaged ∑FAA concentrations on the aerosol particles at the Mt. Verde were lower (submicron: 1.5 ng m−3, supermicron: 1.2 ng m−3) compared to the CVAO. A similar percentage contribution of ∑FAA to dissolved organic carbon (DOC) in the seawater (up to 7.6&tinsp;%) and to water-soluble organic carbon (WSOC) on the submicron aerosol particles (up to 5.3 %) indicated a related transfer process of FAA and DOC in the marine environment. The FAA were strongly enriched in the submicron aerosol particles (EFaer(∑FAA) 4∙102–3∙104, EFaer(WSOC) 2∙103–1∙104), possibly resulting from film droplet formation. The enrichment in supermicron aerosol particles was several orders of magnitude lower compared to supermicron size range with EFaer(∑FAA) 1∙101–2∙101, EFaer(WSOC) 3∙102–4∙102. A case study showed that several amino acids were transported from the ocean up to cloud level (e.g. aspartic acid, glutamic acid, proline) while other amino acids might not be transferred or quickly degraded (e.g. phenylalanine, tyrosine) or produced (e.g. GABA). The cloud water samples exhibited a similar composition of FAA compared to the SML but a strong variation of the atmospheric concentration of ∑FAA during the campaign (11.2–489.9 ng m−3). FAA in cloud water samples showed a strong enrichment by a factor of 4∙103 compared to the SML. The presence of high concentrations of FAA in general and of biologically produced FAA (aspartic acid) in particular together with the presence of inorganic marine tracers (sodium, methane sulfonic acid) demonstrates the influence of oceanic sources on marine clouds.

scholarly journals The Influence of Algal Exudate on the Hygroscopicity of Sea Spray Particles

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
H. Wex ◽  
E. Fuentes ◽  
G. Tsagkogeorgas ◽  
J. Voigtländer ◽  
T. Clauss ◽  
...  
Keyword(s):  
Organic Matter ◽  
Aerosol Particles ◽  
Algal Species ◽  
Artificial Seawater ◽  
Time Range ◽  
Sea Spray ◽  
Marine Aerosol ◽  
Hygroscopic Growth ◽  
Droplet Activation ◽  
Kinetic Effects

We examined the effect of organic matter released by four different algal species on the hygroscopic growth and droplet activation behaviour of laboratory-generated marine aerosol particles. Hygroscopic growth factors and dry diameters for activation were reduced by less than 10%, compared to that of sodium chloride or of artificial seawater that was devoid of marine surfactants. Concentration-dependent nonideal behaviour was observed for the artificial seawater. But within measurement uncertainty, the measured hygroscopic growth and droplet activation behaviour for the samples that contained organic matter were consistent with a hygroscopicity parameter that was constant between the sub- and supersaturated measurement points. Also, the hygroscopic growth measured for hydrated particles after 3 and after 10 seconds was similar, which implies that in this time range no kinetic effects were detected.

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