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Year-round carbon dioxide (CO2) and methane (CH4) concentration measurements, performed for the first time in the city of Athens, Greece from December 21, 2018 to December 31, 2019, are presented in this study and analyzed in relation to atmospheric circulation patterns at a local, regional and long-range transport scale. Clear diurnal and seasonal variations of both greenhouse gases were detected. The observed increased levels during night and early morning hours are attributed to traffic/heating emissions and leakages of residential natural gas for CO2 and CH4, respectively. Using CO2 and CH4 levels simultaneously measured at the regional background site at Finokalia (Greece), increments in their levels due to local and regional anthropogenic sources within the city were assessed. For CO2, maximum and minimum increments were clearly observed during winter and summer respectively, suggesting a greater impact of combustion of fossil fuel and especially of biomass on CO2 levels during winter. On the other hand, CH4 increments were similar in all seasons, suggesting that local sources of CH4 remain quite constant year-round. Through the implementation of the Conditional Probability Function (CPF), the emission sources of theses greenhouse gases have been localized to the northern and the eastern domains of the Athens basin. Stagnant atmospheric conditions were also associated with an increased likelihood of CO2 and CH4 episodes. Backward modeling simulations with FLEXPART and HYSPLIT models indicate an industrial zone and a petrochemical zone, situated to the north and to the west of Athens respectively, as possible CH4 regional sources as well as possible CO2 contributions from southern directions attributed to shipping emissions from the port of Piraeus. The present study provides knowledge needed for the determination of greenhouse gas emission mitigation strategies in Athens.
K. Dimitriou; A. Bougiatioti; M. Ramonet; F. Pierros; P. Michalopoulos; E. Liakakou; S. Solomos; P.-Y. Quehe; M. Delmotte; E. Gerasopoulos; M. Kanakidou. Greenhouse gases (CO2 and CH4) at an urban background site in Athens, Greece: Levels, sources and impact of atmospheric circulation. Atmospheric Environment 2021, 253, 118372 .
AMA StyleK. Dimitriou, A. Bougiatioti, M. Ramonet, F. Pierros, P. Michalopoulos, E. Liakakou, S. Solomos, P.-Y. Quehe, M. Delmotte, E. Gerasopoulos, M. Kanakidou. Greenhouse gases (CO2 and CH4) at an urban background site in Athens, Greece: Levels, sources and impact of atmospheric circulation. Atmospheric Environment. 2021; 253 ():118372.
Chicago/Turabian StyleK. Dimitriou; A. Bougiatioti; M. Ramonet; F. Pierros; P. Michalopoulos; E. Liakakou; S. Solomos; P.-Y. Quehe; M. Delmotte; E. Gerasopoulos; M. Kanakidou. 2021. "Greenhouse gases (CO2 and CH4) at an urban background site in Athens, Greece: Levels, sources and impact of atmospheric circulation." Atmospheric Environment 253, no. : 118372.
Particulate matter (PM) in the atmosphere has diverse natural and anthropogenic sources, and is a complex, heterogeneous mixture
Aikaterini Bougiatioti; Evangelia Kostenidou. Ambient Aerosol Measurements in Different Environments. Atmosphere 2021, 12, 429 .
AMA StyleAikaterini Bougiatioti, Evangelia Kostenidou. Ambient Aerosol Measurements in Different Environments. Atmosphere. 2021; 12 (4):429.
Chicago/Turabian StyleAikaterini Bougiatioti; Evangelia Kostenidou. 2021. "Ambient Aerosol Measurements in Different Environments." Atmosphere 12, no. 4: 429.
During the 2013 Southeast Nexus (SENEX) campaign, in-situ observational data were collected on board the NOAA WP-3D aircraft to study the aerosol-cloud droplet link and examine the sensitivity of the cloud droplet number to aerosol physicochemical parameters. In order to do so, observed aerosol number size distributions, chemical composition and vertical-velocity distributions were introduced into a state-of-the-art cloud droplet parameterization from which cloud droplet number and cloud maximum supersaturations were derived. We find that the standard deviation of the vertical velocity (σw) exhibits significant diurnal variability ranging from 0.16 m s-1 during nighttime to over 1.2 m s-1 during day. Total aerosol number (Na) covaries with σw , with lower values observed during nighttime. The covariance between σw and Na enhances the apparent response of Nd to changes in Na levels by a factor of 5. For the same “cleaner” environments where Na values are limited and not impacted by local sources, the relative response of Nd to σw is almost twice as great during night, compared to the day (24% during day vs. 42% during night). On the other hand, in environment with enhanced concentrations, especially of accumulation-mode particles, the majority of droplet number variability is attributed to changes in total aerosol number rather than changes in σw. Chemical composition is found to on-average have a limited effect on Nd variability (4%). Finally, we identify an upper limit to the number of droplets that can form in clouds which depends only on σw independently from total aerosol number. Doubling σw from 0.2 to 0.3 m s-1increases this limiting droplet number by 52%.When Nd values approach this upper limit the observed droplet variability is driven by σw and, subsequently, by vertical-velocity changes only. Therefore only by using this -σw relationship in regions where velocity-limited conditions are expected, σw can be estimated from retrievals of droplet number and vice versa.
Aikaterini Bougiatioti; Athanasios Nenes; Jack Lin; Charles Brock; Joost de Gouw; Jin Liao; Ann Middlebrook; Andre Welti. Cloud droplet variability in the summertime in the southeast United States: day vs. night. 2021, 1 .
AMA StyleAikaterini Bougiatioti, Athanasios Nenes, Jack Lin, Charles Brock, Joost de Gouw, Jin Liao, Ann Middlebrook, Andre Welti. Cloud droplet variability in the summertime in the southeast United States: day vs. night. . 2021; ():1.
Chicago/Turabian StyleAikaterini Bougiatioti; Athanasios Nenes; Jack Lin; Charles Brock; Joost de Gouw; Jin Liao; Ann Middlebrook; Andre Welti. 2021. "Cloud droplet variability in the summertime in the southeast United States: day vs. night." , no. : 1.
Atmospheric new particle formation (NPF) events taking place over large distances between locations, featuring similar characteristics, have been the focus of studies during the last decade. The exact mechanism which triggers NPF still remains indefinable, so are the circumstances under which simultaneous occurrence of such events take place in different environments, let alone in environments which are parted by over 1200 km. In this study, concurrent number size distribution measurements were conducted in the urban environments of Athens (Greece) and Amman (Jordan) as well as the regional background site of Finokalia, Crete, all located within a distance of almost 1300 km for a 6-month period (February–July 2017). During the study period Athens and Finokalia had similar occurrence of NPF (around 20%), while the occurrence in Amman was double. When focusing on the dynamic characteristics at each site, it occurs that formation and growth rates at Amman are similar to those at Finokalia, while lower values in Athens can be ascribed to a higher pre-existing particle number at this urban site. By comparing common NPF events there are 5 concomitant days between all three sites, highly related to air masses origin. Additionally, for another 19 days NPF takes place simultaneously between Finokalia and Amman, which also share common meteorological characteristics, adding to a total of 60% out of 41 NPF events observed at Finokalia, also simultaneously occurring in Amman.
Panayiotis Kalkavouras; Aikaterini BougiatiotI; Tareq Hussein; Nikos Kalivitis; Iasonas Stavroulas; Panagiotis Michalopoulos; Nikolaos Mihalopoulos. Regional New Particle Formation over the Eastern Mediterranean and Middle East. Atmosphere 2020, 12, 13 .
AMA StylePanayiotis Kalkavouras, Aikaterini BougiatiotI, Tareq Hussein, Nikos Kalivitis, Iasonas Stavroulas, Panagiotis Michalopoulos, Nikolaos Mihalopoulos. Regional New Particle Formation over the Eastern Mediterranean and Middle East. Atmosphere. 2020; 12 (1):13.
Chicago/Turabian StylePanayiotis Kalkavouras; Aikaterini BougiatiotI; Tareq Hussein; Nikos Kalivitis; Iasonas Stavroulas; Panagiotis Michalopoulos; Nikolaos Mihalopoulos. 2020. "Regional New Particle Formation over the Eastern Mediterranean and Middle East." Atmosphere 12, no. 1: 13.
The lockdown measures implemented worldwide to slow the spread of the COVID–19 pandemic have allowed for a unique real-world experiment, regarding the impacts of drastic emission cutbacks on urban air quality. In this study we assess the effects of a 7-week (23 March–10 May 2020) lockdown in the Greater Area of Athens, coupling in situ observations with estimations from a meteorology-atmospheric chemistry model. Measurements in central Athens during the lockdown were compared with levels during the pre- and post-lockdown 3-week periods and with respective levels in the four previous years. We examined regulatory pollutants as well as CO2, black carbon (BC) and source-specific BC components. Models were run for pre-lockdown and lockdown periods, under baseline and reduced-emissions scenarios. The in-situ results indicate mean concentration reductions of 30–35% for traffic-related pollutants in Athens (NO2, CO, BC from fossil fuel combustion), compared to the pre-lockdown period. A large reduction (53%) was observed also for the urban CO2 enhancement while the reduction for PM2.5 was subtler (18%). Significant reductions were also observed when comparing the 2020 lockdown period with past years. However, levels rebounded immediately following the lift of the general lockdown. The decrease in measured NO2 concentrations was reproduced by the implementation of the city scale model, under a realistic reduced-emissions scenario for the lockdown period, anchored at a 46% decline of road transport activity. The model permitted the assessment of air quality improvements on a spatial scale, indicating that NO2 mean concentration reductions in areas of the Athens basin reached up to 50%. The findings suggest a potential for local traffic management strategies to reduce ambient exposure and to minimize exceedances of air quality standards for primary pollutants.
Georgios Grivas; Eleni Athanasopoulou; Anastasia Kakouri; Jennifer Bailey; Eleni Liakakou; Iasonas Stavroulas; Panayiotis Kalkavouras; Aikaterini Bougiatioti; Dimitris Kaskaoutis; Michel Ramonet; Nikolaos Mihalopoulos; Evangelos Gerasopoulos. Integrating in situ Measurements and City Scale Modelling to Assess the COVID–19 Lockdown Effects on Emissions and Air Quality in Athens, Greece. Atmosphere 2020, 11, 1174 .
AMA StyleGeorgios Grivas, Eleni Athanasopoulou, Anastasia Kakouri, Jennifer Bailey, Eleni Liakakou, Iasonas Stavroulas, Panayiotis Kalkavouras, Aikaterini Bougiatioti, Dimitris Kaskaoutis, Michel Ramonet, Nikolaos Mihalopoulos, Evangelos Gerasopoulos. Integrating in situ Measurements and City Scale Modelling to Assess the COVID–19 Lockdown Effects on Emissions and Air Quality in Athens, Greece. Atmosphere. 2020; 11 (11):1174.
Chicago/Turabian StyleGeorgios Grivas; Eleni Athanasopoulou; Anastasia Kakouri; Jennifer Bailey; Eleni Liakakou; Iasonas Stavroulas; Panayiotis Kalkavouras; Aikaterini Bougiatioti; Dimitris Kaskaoutis; Michel Ramonet; Nikolaos Mihalopoulos; Evangelos Gerasopoulos. 2020. "Integrating in situ Measurements and City Scale Modelling to Assess the COVID–19 Lockdown Effects on Emissions and Air Quality in Athens, Greece." Atmosphere 11, no. 11: 1174.
Here we analyze regional-scale data collected on board the NOAA WP-3D aircraft during the 2013 Southeast Nexus (SENEX) campaign to study the aerosol–cloud droplet link and quantify the sensitivity of droplet number to aerosol number, chemical composition, and vertical velocity. For this, the observed aerosol size distributions, chemical composition, and vertical-velocity distribution are introduced into a state-of-the-art cloud droplet parameterization to show that cloud maximum supersaturations in the region range from 0.02 % to 0.52 %, with an average of 0.14±0.05 %. Based on these low values of supersaturation, the majority of activated droplets correspond to particles with a dry diameter of 90 nm and above. An important finding is that the standard deviation of the vertical velocity (σw) exhibits considerable diurnal variability (ranging from 0.16 m s−1 during nighttime to over 1.2 m s−1 during day), and it tends to covary with total aerosol number (Na). This σw–Na covariance amplifies the predicted response in cloud droplet number (Nd) to Na increases by 3 to 5 times compared to expectations based on Na changes alone. This amplified response is important given that droplet formation is often velocity-limited and therefore should normally be insensitive to aerosol changes. We also find that Nd cannot exceed a characteristic concentration that depends solely on σw. Correct consideration of σw and its covariance with time and Na is important for fully understanding aerosol–cloud interactions and the magnitude of the aerosol indirect effect. Given that model assessments of aerosol–cloud–climate interactions do not routinely evaluate for overall turbulence or its covariance with other parameters, datasets and analyses such as the one presented here are of the highest priority to address unresolved sources of hydrometeor variability, bias, and the response of droplet number to aerosol perturbations.
Aikaterini Bougiatioti; Athanasios Nenes; Jack J. Lin; Charles A. Brock; Joost A. De Gouw; Jin Liao; Ann M. Middlebrook; André Welti. Drivers of cloud droplet number variability in the summertime in the southeastern United States. Atmospheric Chemistry and Physics 2020, 20, 12163 -12176.
AMA StyleAikaterini Bougiatioti, Athanasios Nenes, Jack J. Lin, Charles A. Brock, Joost A. De Gouw, Jin Liao, Ann M. Middlebrook, André Welti. Drivers of cloud droplet number variability in the summertime in the southeastern United States. Atmospheric Chemistry and Physics. 2020; 20 (20):12163-12176.
Chicago/Turabian StyleAikaterini Bougiatioti; Athanasios Nenes; Jack J. Lin; Charles A. Brock; Joost A. De Gouw; Jin Liao; Ann M. Middlebrook; André Welti. 2020. "Drivers of cloud droplet number variability in the summertime in the southeastern United States." Atmospheric Chemistry and Physics 20, no. 20: 12163-12176.
Despite the various reduction policies that have been implemented across Europe in the past few years, Particulate Matter (PM) exceedances continue to be recorded. Therefore, with the principal aim to clarify the complex association between emissions and fine particles levels, this work evaluates the impact of the anthropogenic contribution to the fine PM chemical profile. The fieldwork was conducted during March in 2008 and 2013 and covers the periods before and during the economic recession. The experimental data were analyzed in parallel with the emissions from the Flexible Emission Inventory for Greece and the Greater Athens Area (FEI-GREGAA). The differentiation of the mass closure results’ and the aerosols’ character is also discussed in combination with the calculated PM2.5-Air Quality Indexes. The peak in the PM load and the Particulate Organic Matter (POM) component was recorded in 2013, corresponding to the enhancement of the anthropogenic input. Although the monitoring location is traffic-impacted, the sector of heating, from both wood burning and fossil fuel, proved to be the driving force for the configuration of the obtained PM picture. Especially in 2013, its contribution was two times that of traffic. Finally, the low wind speed values led to the deterioration of the air quality, especially for the sensitive groups.
Styliani Pateraki; Kyriaki-Maria Fameli; Vasiliki Assimakopoulos; Kyriaki Bairachtari; Alexandros Zagkos; Theodora Stavraka; Aikaterini Bougiatioti; Thomas Maggos; Nikolaos Mihalopoulos. Differentiation of the Athens Fine PM Profile during Economic Recession (March of 2008 versus March of 2013): Impact of Changes in Anthropogenic Emissions and the Associated Health Effect. Atmosphere 2020, 11, 1121 .
AMA StyleStyliani Pateraki, Kyriaki-Maria Fameli, Vasiliki Assimakopoulos, Kyriaki Bairachtari, Alexandros Zagkos, Theodora Stavraka, Aikaterini Bougiatioti, Thomas Maggos, Nikolaos Mihalopoulos. Differentiation of the Athens Fine PM Profile during Economic Recession (March of 2008 versus March of 2013): Impact of Changes in Anthropogenic Emissions and the Associated Health Effect. Atmosphere. 2020; 11 (10):1121.
Chicago/Turabian StyleStyliani Pateraki; Kyriaki-Maria Fameli; Vasiliki Assimakopoulos; Kyriaki Bairachtari; Alexandros Zagkos; Theodora Stavraka; Aikaterini Bougiatioti; Thomas Maggos; Nikolaos Mihalopoulos. 2020. "Differentiation of the Athens Fine PM Profile during Economic Recession (March of 2008 versus March of 2013): Impact of Changes in Anthropogenic Emissions and the Associated Health Effect." Atmosphere 11, no. 10: 1121.
Recent advances in particle sensor technologies have led to an increased development and utilization of low-cost, compact, particulate matter (PM) monitors. These devices can be deployed in dense monitoring networks, enabling an improved characterization of the spatiotemporal variability in ambient levels and exposure. However, the reliability of their measurements is an important prerequisite, necessitating rigorous performance evaluation and calibration in comparison to reference-grade instrumentation. In this study, field evaluation of Purple Air PA-II devices (low-cost PM sensors) is performed in two urban environments and across three seasons in Greece, in comparison to different types of reference instruments. Measurements were conducted in Athens (the largest city in Greece with nearly four-million inhabitants) for five months spanning over the summer of 2019 and winter/spring of 2020 and in Ioannina, a medium-sized city in northwestern Greece (100,000 inhabitants) during winter/spring 2019–2020. The PM2.5 sensor output correlates strongly with reference measurements (R2 = 0.87 against a beta attenuation monitor and R2 = 0.98 against an optical reference-grade monitor). Deviations in the sensor-reference agreement are identified as mainly related to elevated coarse particle concentrations and high ambient relative humidity. Simple and multiple regression models are tested to compensate for these biases, drastically improving the sensor’s response. Large decreases in sensor error are observed after implementation of models, leading to mean absolute percentage errors of 0.18 and 0.12 for the Athens and Ioannina datasets, respectively. Overall, a quality-controlled and robustly evaluated low-cost network can be an integral component for air quality monitoring in a smart city. Case studies are presented along this line, where a network of PA-II devices is used to monitor the air quality deterioration during a peri-urban forest fire event affecting the area of Athens and during extreme wintertime smog events in Ioannina, related to wood burning for residential heating.
Iasonas Stavroulas; Georgios Grivas; Panagiotis Michalopoulos; Eleni Liakakou; Aikaterini Bougiatioti; Panayiotis Kalkavouras; Kyriaki Fameli; Nikolaos Hatzianastassiou; Nikolaos Mihalopoulos; Evangelos Gerasopoulos. Field Evaluation of Low-Cost PM Sensors (Purple Air PA-II) Under Variable Urban Air Quality Conditions, in Greece. Atmosphere 2020, 11, 926 .
AMA StyleIasonas Stavroulas, Georgios Grivas, Panagiotis Michalopoulos, Eleni Liakakou, Aikaterini Bougiatioti, Panayiotis Kalkavouras, Kyriaki Fameli, Nikolaos Hatzianastassiou, Nikolaos Mihalopoulos, Evangelos Gerasopoulos. Field Evaluation of Low-Cost PM Sensors (Purple Air PA-II) Under Variable Urban Air Quality Conditions, in Greece. Atmosphere. 2020; 11 (9):926.
Chicago/Turabian StyleIasonas Stavroulas; Georgios Grivas; Panagiotis Michalopoulos; Eleni Liakakou; Aikaterini Bougiatioti; Panayiotis Kalkavouras; Kyriaki Fameli; Nikolaos Hatzianastassiou; Nikolaos Mihalopoulos; Evangelos Gerasopoulos. 2020. "Field Evaluation of Low-Cost PM Sensors (Purple Air PA-II) Under Variable Urban Air Quality Conditions, in Greece." Atmosphere 11, no. 9: 926.
Atmospheric new particle formation (NPF) is an important source of submicron particles. In remote background environments where local sources are scarce such processes may impact significantly on climate-relevant parameters. On the other hand, in urban environments, newly-formed particles are adding up to submicron particles emitted from primary sources. As the exact mechanism which triggers NPF still remains elusive, so are the circumstances for simultaneous occurrence of such events in two different environments (urban vs. regional background). In this study, concurrent number size distribution measurements were conducted in the urban environment of Athens and at the regional background site of Finokalia, Crete, located 340 km away and spanning a 2-year period. It occurred that the relative frequency of NPF was similar at both sites (around 20%), with a higher frequency during spring and autumn at the urban site, while at the background site most events took place in August and December, during the studied period. There were 35 event days when NPF took place at both sites simultaneously, all associated with air masses originating from the Northern sector, indicating the presence of regional events in the extended geographical area and characterized by low condensation sink (CS). By comparing the common with the non-common class I NPF episodes, we conclude that the conditions applying when regional NPF events with growth are observed in the same day at the surface level of both areas, are: (i) lower CS, (ii) higher SO2 concentrations, (iii) lower RH, and finally (iv) lower formation and growth rates than those observed during the site-specific and more rapidly evolving NPF events.
Panayiotis Kalkavouras; Aikaterini Bougiatioti; Georgios Grivas; Iasonas Stavroulas; Nikos Kalivitis; Eleni Liakakou; Evangelos Gerasopoulos; Christodoulos Pilinis; Nikolaos Mihalopoulos. On the regional aspects of new particle formation in the Eastern Mediterranean: A comparative study between a background and an urban site based on long term observations. Atmospheric Research 2020, 239, 104911 .
AMA StylePanayiotis Kalkavouras, Aikaterini Bougiatioti, Georgios Grivas, Iasonas Stavroulas, Nikos Kalivitis, Eleni Liakakou, Evangelos Gerasopoulos, Christodoulos Pilinis, Nikolaos Mihalopoulos. On the regional aspects of new particle formation in the Eastern Mediterranean: A comparative study between a background and an urban site based on long term observations. Atmospheric Research. 2020; 239 ():104911.
Chicago/Turabian StylePanayiotis Kalkavouras; Aikaterini Bougiatioti; Georgios Grivas; Iasonas Stavroulas; Nikos Kalivitis; Eleni Liakakou; Evangelos Gerasopoulos; Christodoulos Pilinis; Nikolaos Mihalopoulos. 2020. "On the regional aspects of new particle formation in the Eastern Mediterranean: A comparative study between a background and an urban site based on long term observations." Atmospheric Research 239, no. : 104911.
This study analyses 4-years of continuous 7-λ Aethalometer (AE-33) measurements in an urban-background environment of Athens, to resolve the spectral absorption coefficients (babs) for black carbon (BC) and brown carbon (BrC). An important BrC contribution (23.7 ± 11.6%) to the total babs at 370 nm is estimated for the period May 2015–April 2019, characterized by a remarkable seasonality with winter maximum (33.5 ± 13.6%) and summer minimum (18.5 ± 8.1%), while at longer wavelengths the BrC contribution is significantly reduced (6.8 ± 3.6% at 660 nm). The wavelength dependence of the total babs gives an annual-mean AAE370-880 of 1.31, with higher values in winter night-time. The BrC absorption and its contribution to babs presents a large increase reaching up to 39.1 ± 13.6% during winter nights (370 nm), suggesting residential wood burning (RWB) emissions as a dominant source for BrC. This is supported by strong correlations of the BrC absorption with OC, EC, the fragment ion m/z 60 derived from ACSM and PMF-analyzed organic fractions related to biomass burning (e.g. BBOA). In contrast, BrC absorption decreases significantly during daytime as well as in the warm period, reaching to a minimum during the early-afternoon hours in all seasons due to photo-chemical degradation. Estimated secondary BrC absorption is practically evident only during winter night-time, implying the fast oxidation of BrC species from RWB emissions. Changes in mixing-layer height do not significantly affect the BrC absorption in winter, while they play a major role in summer.
E. Liakakou; D.G. Kaskaoutis; G. Grivas; I. Stavroulas; M. Tsagkaraki; Despina Paraskevopoulou; Aikaterini Bougiatioti; Umesh Chandra Dumka; E. Gerasopoulos; N. Mihalopoulos. Long-term brown carbon spectral characteristics in a Mediterranean city (Athens). Science of The Total Environment 2019, 708, 135019 .
AMA StyleE. Liakakou, D.G. Kaskaoutis, G. Grivas, I. Stavroulas, M. Tsagkaraki, Despina Paraskevopoulou, Aikaterini Bougiatioti, Umesh Chandra Dumka, E. Gerasopoulos, N. Mihalopoulos. Long-term brown carbon spectral characteristics in a Mediterranean city (Athens). Science of The Total Environment. 2019; 708 ():135019.
Chicago/Turabian StyleE. Liakakou; D.G. Kaskaoutis; G. Grivas; I. Stavroulas; M. Tsagkaraki; Despina Paraskevopoulou; Aikaterini Bougiatioti; Umesh Chandra Dumka; E. Gerasopoulos; N. Mihalopoulos. 2019. "Long-term brown carbon spectral characteristics in a Mediterranean city (Athens)." Science of The Total Environment 708, no. : 135019.
This study aims to delineate the characteristics of Black Carbon (BC) in the atmosphere over Athens, Greece, using 4-year (May 2015–April 2019) Aethalometer (AE-33) measurements. The average BC concentration is 1.9 ± 2.5 μg m−3 (ranging from 0.1 to 32.7 μg m−3; hourly values), with a well-defined seasonality from 1.3 ± 1.1 μg m−3 in summer to 3.0 ± 4.0 μg m−3 in winter. Pronounced morning and evening/night peaks are found in the BC concentrations in winter, while during the rest of the seasons, this diurnal cycle appears to flatten out, with the exception of the morning traffic peak. On an annual basis, the biomass-burning fraction (BB%) of BC accounts for 22 ± 12%, while the fossil-fuel combustion (BCff) component (traffic emissions and domestic heating) dominates during summer (83%) and in the morning hours. BCwb exhibits higher contribution in winter (32%), especially during the night hours (39%). BC levels are effectively reduced by precipitation, while they significantly build-up for wind speeds <3 m s−1 and mixing-layer height (MLH) < 500 m. Normalizing the BC diurnal course by the MLH variations on a seasonal basis reveals that the residential wood-burning emissions are mostly responsible for the large BC increase during winter nights, whereas the low BC levels during daytime in the warm season are mainly attributed to dilution into a deeper MLH. BCwb is highly correlated with other BB tracers during winter nights (e.g. levoglucosan, non-sea-salt-K+, m/z 60 fragment), as well as with the fine fraction (PM2.5) OC and EC. The Delta-C, which represents the spectral dependence of BC as the absorption difference between 370 and 880 nm, is analyzed for the first time in Athens. It exhibits a pronounced seasonality with maximum values in winter night-time, and it appears as a valid qualitative marker for wood combustion.
E. Liakakou; I. Stavroulas; D.G. Kaskaoutis; G. Grivas; D. Paraskevopoulou; U.C. Dumka; M. Tsagkaraki; Aikaterini Bougiatioti; K. Oikonomou; J. Sciare; E. Gerasopoulos; N. Mihalopoulos. Long-term variability, source apportionment and spectral properties of black carbon at an urban background site in Athens, Greece. Atmospheric Environment 2019, 222, 117137 .
AMA StyleE. Liakakou, I. Stavroulas, D.G. Kaskaoutis, G. Grivas, D. Paraskevopoulou, U.C. Dumka, M. Tsagkaraki, Aikaterini Bougiatioti, K. Oikonomou, J. Sciare, E. Gerasopoulos, N. Mihalopoulos. Long-term variability, source apportionment and spectral properties of black carbon at an urban background site in Athens, Greece. Atmospheric Environment. 2019; 222 ():117137.
Chicago/Turabian StyleE. Liakakou; I. Stavroulas; D.G. Kaskaoutis; G. Grivas; D. Paraskevopoulou; U.C. Dumka; M. Tsagkaraki; Aikaterini Bougiatioti; K. Oikonomou; J. Sciare; E. Gerasopoulos; N. Mihalopoulos. 2019. "Long-term variability, source apportionment and spectral properties of black carbon at an urban background site in Athens, Greece." Atmospheric Environment 222, no. : 117137.
A first assessment of the spatial variability of ambient black carbon (BC) concentrations in the Greater Area of Athens (GAA) was carried out during an intensive wintertime campaign, when ambient levels are exacerbated by increased biomass burning for residential heating. Short-term daytime BC measurements were conducted at 50 sites (traffic and urban/suburban/regional background) and on-road along 12 routes. Daytime measurements were adjusted based on BC concentrations continuously monitored at a reference site. Indicative nighttime BC ambient concentrations were also measured at several residences across the area. Daytime BC concentrations recorded an average of 2.3 μg m-3 with considerable between-site variability. Concentrations at traffic sites were significantly higher (43% on average), compared with the rest of the sites. Varying levels were observed between background site subtypes, with concentrations at urban background sites (located near the center of Athens and the port of Piraeus) being 34% and 114% higher, on average, than at suburban and regional background sites, respectively. The traffic intensity at the nearest road and the population and built density in the surrounding area of sites were recognized as important factors controlling BC levels. On-road concentration measurements (5.4 μg m-3 on average) enabled the identification of hot-spots in the road network, with peak levels encountered along motorways (13.5 μg m-3 on average). Nighttime measurements demonstrated that wintertime BC pollution, enhanced by residential biomass burning for heating, affects the entire Athens basin. The reference site in central Athens was found to be representative of the temporal variability for daytime and nighttime BC concentrations at background locations.
Georgios Grivas; Iasonas Stavroulas; Eleni Liakakou; Dimitris G. Kaskaoutis; Aikaterini Bougiatioti; Despina Paraskevopoulou; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. Measuring the spatial variability of black carbon in Athens during wintertime. Air Quality, Atmosphere & Health 2019, 12, 1405 -1417.
AMA StyleGeorgios Grivas, Iasonas Stavroulas, Eleni Liakakou, Dimitris G. Kaskaoutis, Aikaterini Bougiatioti, Despina Paraskevopoulou, Evangelos Gerasopoulos, Nikolaos Mihalopoulos. Measuring the spatial variability of black carbon in Athens during wintertime. Air Quality, Atmosphere & Health. 2019; 12 (12):1405-1417.
Chicago/Turabian StyleGeorgios Grivas; Iasonas Stavroulas; Eleni Liakakou; Dimitris G. Kaskaoutis; Aikaterini Bougiatioti; Despina Paraskevopoulou; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. 2019. "Measuring the spatial variability of black carbon in Athens during wintertime." Air Quality, Atmosphere & Health 12, no. 12: 1405-1417.
Fine particulate matter (PM) has significant impacts on public health. Among its various chemical components, Polycyclic Aromatic Hydrocarbons (PAHs) are of particular importance since they contribute to a large extent or even enhance its toxic potency. Despite the verified importance of the fine PM pollution for the Greater Athens Area (GAA), information on its composition with respect to the hydrocarbons is extremely scarce. This study aims to uncover the occurrence of the PM2.5 and PM1-bound PAHs across the GAA investigating the impact of the sources and meteorology on the configuration of their profile and potential health risk. The fieldwork took place at three different locations during two different mesoscale wind regimes. Using the Diagnostic PAHs’ Ratio method, the sources were identified while for the quantification of the emissions from the traffic and central heating sectors, the FEI-GREGAA emission inventory was taken into consideration. The potential health risk was estimated calculating the toxic/mutagenic equivalency factors. The peaks for both the PM mass and the PAHs were attributed to the intensity of the emissions. On the other hand, the carcinogenic/mutagenic risk was mainly influenced by the varying characteristics of traffic and especially for the background atmosphere, from the arriving air masses from longer scale distances.
Styliani Pateraki; Kyriaki-Maria Fameli; Vasiliki Assimakopoulos; Aikaterini Bougiatioti; Thomas Maggos; Nikolaos Mihalopoulos. Levels, Sources and Health Risk of PM2.5 and PM1-Bound PAHs across the Greater Athens Area: The Role of the Type of Environment and the Meteorology. Atmosphere 2019, 10, 622 .
AMA StyleStyliani Pateraki, Kyriaki-Maria Fameli, Vasiliki Assimakopoulos, Aikaterini Bougiatioti, Thomas Maggos, Nikolaos Mihalopoulos. Levels, Sources and Health Risk of PM2.5 and PM1-Bound PAHs across the Greater Athens Area: The Role of the Type of Environment and the Meteorology. Atmosphere. 2019; 10 (10):622.
Chicago/Turabian StyleStyliani Pateraki; Kyriaki-Maria Fameli; Vasiliki Assimakopoulos; Aikaterini Bougiatioti; Thomas Maggos; Nikolaos Mihalopoulos. 2019. "Levels, Sources and Health Risk of PM2.5 and PM1-Bound PAHs across the Greater Athens Area: The Role of the Type of Environment and the Meteorology." Atmosphere 10, no. 10: 622.
With the principal aim to assess the typical Mediterranean profile of the PM2.5 and PM1 pollution, three intensive monitoring campaigns took place simultaneously within different types of environment across an urban location of the basin. Focusing on the PM components with numerous anthropogenic sources and increased potential health risk, the samples were chemically analyzed for 20 p.m.-bound Polycyclic Aromatic Hydrocarbons (PAHs). Carbonaceous and ionic constituents were quantified as well. In order to uncover the spatiotemporal variation of the PM profile the key sources were identified, the seasonal effects and the role of the prevailing mesoscale atmospheric circulation were evaluated and most importantly the potential health risk was estimated. In general, the pollution status of the basin was the result of a complex interaction between the local and external input with Particulate Organic Matter (POM) and Secondary Inorganic Aerosols (SIA) being the main aerosols’ components. PM1 was a better indicator of the anthropogenic emissions while according to the results of factor analysis the co-existence of various combustion sources was determinant. Chemically, the maxima of the ΣPAHs, the differentiation of their structure in accordance with their molecular weight and the distribution of the individual compounds confirmed the significance of the emission sources. Similarly, the estimated carcinogenicity/mutagenicity was emission-dependent with the maximum contribution coming from B[a]P, IndP, B[ghi]Per, B[e]P and B[b]F. Seasonally, the highest potential health risk of the PAHs’ mixture was recorded during the cold season while meteorologically, it was mostly associated with the south flow.
St. Pateraki; D.N. Asimakopoulos; Thomas Maggos; V.D. Assimakopoulos; Aikaterini Bougiatioti; K. Bairachtari; Ch. Vasilakos; N. Mihalopoulos. Chemical characterization, sources and potential health risk of PM2.5 and PM1 pollution across the Greater Athens Area. Chemosphere 2019, 241, 125026 .
AMA StyleSt. Pateraki, D.N. Asimakopoulos, Thomas Maggos, V.D. Assimakopoulos, Aikaterini Bougiatioti, K. Bairachtari, Ch. Vasilakos, N. Mihalopoulos. Chemical characterization, sources and potential health risk of PM2.5 and PM1 pollution across the Greater Athens Area. Chemosphere. 2019; 241 ():125026.
Chicago/Turabian StyleSt. Pateraki; D.N. Asimakopoulos; Thomas Maggos; V.D. Assimakopoulos; Aikaterini Bougiatioti; K. Bairachtari; Ch. Vasilakos; N. Mihalopoulos. 2019. "Chemical characterization, sources and potential health risk of PM2.5 and PM1 pollution across the Greater Athens Area." Chemosphere 241, no. : 125026.
During the summer of 2012 a coordinated field campaign was conducted in multiple locations in Greece in order to characterize the ambient particulate matter (PM) levels, its chemical composition and the contribution of the regional and local sources. PM1, PM2.5 and PM10 samples were collected simultaneously at seven different sites in Greece: an urban and a suburban station in Patras, a suburban station in Thessaloniki, a suburban and an urban background station in Athens, a rural background station at the Navarino Environmental Observatory (NEO) in southwestern Peloponnese and a remote background site at Finokalia in the northeastern part of Crete. The sites were selected to facilitate the estimation of the contribution of the local emission sources and long range transport. Sulfate and organics were the major PM1 components in all sites suggesting that high sulfate levels still remain in parts of Europe. The photochemistry of the Eastern Mediterranean can convert rapidly the emitted sulphur dioxide to sulfate. Our analysis indicated significant sulfate production over the area, with high sulfate levels, especially in the remote site of Finokalia, associated with air masses that had passed over Turkey. There was high regional secondary organic aerosol production dominating organic aerosol levels even in a major city like Athens. High organic aerosol levels were associated with air masses that had crossed the Balkans with a significant biogenic component. The average PM2.5 concentration ranged from 13 to 18 μg m−3 in the different sites. There were unexpected significant gradients in the concentrations of secondary aerosol components in length scales of a few hundred kilometers. The low concentrations of measured PM2.5 nitrate are mostly organic nitrates and supermicrometer nitrate associated with sea-salt and dust. Dust was a significant PM10 constituent in all areas and was quite variable in space showing the importance of the local sources.
M.A. Tsiflikiotou; E. Kostenidou; Dimitrios Papanastasiou; D. Patoulias; P. Zarmpas; Despina Paraskevopoulou; E. Diapouli; Christos Kaltsonoudis; K. Florou; Aikaterini Bougiatioti; I. Stavroulas; C. Theodosi; G. Kouvarakis; V. Vasilatou; D. Siakavaras; G. Biskos; C. Pilinis; K. Eleftheriadis; E. Gerasopoulos; N. Mihalopoulos; S.N. Pandis. Summertime particulate matter and its composition in Greece. Atmospheric Environment 2019, 213, 597 -607.
AMA StyleM.A. Tsiflikiotou, E. Kostenidou, Dimitrios Papanastasiou, D. Patoulias, P. Zarmpas, Despina Paraskevopoulou, E. Diapouli, Christos Kaltsonoudis, K. Florou, Aikaterini Bougiatioti, I. Stavroulas, C. Theodosi, G. Kouvarakis, V. Vasilatou, D. Siakavaras, G. Biskos, C. Pilinis, K. Eleftheriadis, E. Gerasopoulos, N. Mihalopoulos, S.N. Pandis. Summertime particulate matter and its composition in Greece. Atmospheric Environment. 2019; 213 ():597-607.
Chicago/Turabian StyleM.A. Tsiflikiotou; E. Kostenidou; Dimitrios Papanastasiou; D. Patoulias; P. Zarmpas; Despina Paraskevopoulou; E. Diapouli; Christos Kaltsonoudis; K. Florou; Aikaterini Bougiatioti; I. Stavroulas; C. Theodosi; G. Kouvarakis; V. Vasilatou; D. Siakavaras; G. Biskos; C. Pilinis; K. Eleftheriadis; E. Gerasopoulos; N. Mihalopoulos; S.N. Pandis. 2019. "Summertime particulate matter and its composition in Greece." Atmospheric Environment 213, no. : 597-607.
D. Paraskevopoulou; A. Bougiatioti; I. Stavroulas; T. Fang; M. Lianou; E. Liakakou; E. Gerasopoulos; R. Weber; A. Nenes; N. Mihalopoulos. Yearlong variability of oxidative potential of particulate matter in an urban Mediterranean environment. Atmospheric Environment 2019, 206, 183 -196.
AMA StyleD. Paraskevopoulou, A. Bougiatioti, I. Stavroulas, T. Fang, M. Lianou, E. Liakakou, E. Gerasopoulos, R. Weber, A. Nenes, N. Mihalopoulos. Yearlong variability of oxidative potential of particulate matter in an urban Mediterranean environment. Atmospheric Environment. 2019; 206 ():183-196.
Chicago/Turabian StyleD. Paraskevopoulou; A. Bougiatioti; I. Stavroulas; T. Fang; M. Lianou; E. Liakakou; E. Gerasopoulos; R. Weber; A. Nenes; N. Mihalopoulos. 2019. "Yearlong variability of oxidative potential of particulate matter in an urban Mediterranean environment." Atmospheric Environment 206, no. : 183-196.
This work describes results obtained from the 2016 Aerosol Chemical Speciation Monitor (ACSM) intercomparison exercise performed at the Aerosol Chemical Monitor Calibration Centre (ACMCC, France). Fifteen quadrupole ACSMs (Q_ACSM) from the European Research Infrastructure for the observation of Aerosols, Clouds and Trace gases (ACTRIS) network were calibrated using a new procedure that acquires calibration data under the same operating conditions as those used during sampling and hence gets information representative of instrument performance. The new calibration procedure notably resulted in a decrease in the spread of the measured sulphate mass concentrations, improving the reproducibility of inorganic species measurements between ACSMs as well as the consistency with co-located independent instruments. Tested calibration procedures also allowed for the investigation of artefacts in individual instruments, such as the overestimation of m/z 44 from organic aerosol. This effect was quantified by the m/z (mass-to-charge) 44 to nitrate ratio measured during ammonium nitrate calibrations, with values ranging from 0.03 up to 0.26, showing that it can be significant for some instruments. The fragmentation table correction previously proposed to account for this artefact was applied to the measurements acquired during this study. For some instruments (those with high artefacts), this fragmentation table adjustment led to an “overcorrection” of the f44 (m/z 44/Org) signal. This correction based on measurements made with pure NH4NO3, assumes that the magnitude of the artefact is independent of chemical composition. Using data acquired at different NH4NO3 mixing ratios (from solutions of NH4NO3 and (NH4)2SO4) we observe that the magnitude of the artefact varies as a function of composition. Here we applied an updated correction, dependent on the ambient NO3 mass fraction, which resulted in an improved agreement in organic signal among instruments. This work illustrates the benefits of integrating new calibration procedures and artefact corrections, but also highlights the benefits of these intercomparison exercises to continue to improve our knowledge of how these instruments operate, and assist us in interpreting atmospheric chemistry.
Evelyn Freney; Yunjiang Zhang; Philip Croteau; Tanguy Amodeo; Leah Williams; François Truong; Jean-Eudes Petit; Jean Sciare; Roland Sarda-Esteve; Nicolas Bonnaire; Tarvo Arumae; Minna Aurela; Aikaterini Bougiatioti; Nikolaos Mihalopoulos; Esther Coz; Begoña Artinano; Vincent Crenn; Thomas Elste; Liine Heikkinen; Laurent Poulain; Alfred Wiedensohler; Hartmut Herrmann; Max Priestman; Andres Alastuey; Iasonas Stavroulas; Anna Tobler; Jeni Vasilescu; Nicola Zanca; Manjula Canagaratna; Claudio Carbone; Harald Flentje; David Green; Marek Maasikmets; Luminita Marmureanu; Maria Cruz Minguillon; Andre S. H. Prevot; Valerie Gros; John Jayne; Olivier Favez. The second ACTRIS inter-comparison (2016) for Aerosol Chemical Speciation Monitors (ACSM): Calibration protocols and instrument performance evaluations. Aerosol Science and Technology 2019, 53, 830 -842.
AMA StyleEvelyn Freney, Yunjiang Zhang, Philip Croteau, Tanguy Amodeo, Leah Williams, François Truong, Jean-Eudes Petit, Jean Sciare, Roland Sarda-Esteve, Nicolas Bonnaire, Tarvo Arumae, Minna Aurela, Aikaterini Bougiatioti, Nikolaos Mihalopoulos, Esther Coz, Begoña Artinano, Vincent Crenn, Thomas Elste, Liine Heikkinen, Laurent Poulain, Alfred Wiedensohler, Hartmut Herrmann, Max Priestman, Andres Alastuey, Iasonas Stavroulas, Anna Tobler, Jeni Vasilescu, Nicola Zanca, Manjula Canagaratna, Claudio Carbone, Harald Flentje, David Green, Marek Maasikmets, Luminita Marmureanu, Maria Cruz Minguillon, Andre S. H. Prevot, Valerie Gros, John Jayne, Olivier Favez. The second ACTRIS inter-comparison (2016) for Aerosol Chemical Speciation Monitors (ACSM): Calibration protocols and instrument performance evaluations. Aerosol Science and Technology. 2019; 53 (7):830-842.
Chicago/Turabian StyleEvelyn Freney; Yunjiang Zhang; Philip Croteau; Tanguy Amodeo; Leah Williams; François Truong; Jean-Eudes Petit; Jean Sciare; Roland Sarda-Esteve; Nicolas Bonnaire; Tarvo Arumae; Minna Aurela; Aikaterini Bougiatioti; Nikolaos Mihalopoulos; Esther Coz; Begoña Artinano; Vincent Crenn; Thomas Elste; Liine Heikkinen; Laurent Poulain; Alfred Wiedensohler; Hartmut Herrmann; Max Priestman; Andres Alastuey; Iasonas Stavroulas; Anna Tobler; Jeni Vasilescu; Nicola Zanca; Manjula Canagaratna; Claudio Carbone; Harald Flentje; David Green; Marek Maasikmets; Luminita Marmureanu; Maria Cruz Minguillon; Andre S. H. Prevot; Valerie Gros; John Jayne; Olivier Favez. 2019. "The second ACTRIS inter-comparison (2016) for Aerosol Chemical Speciation Monitors (ACSM): Calibration protocols and instrument performance evaluations." Aerosol Science and Technology 53, no. 7: 830-842.
A significant fraction of atmospheric particles that serve as cloud condensation nuclei (CCN) are thought to originate from the condensational growth of new particle formation (NPF) from the gas phase. Here, 7 years of continuous aerosol and meteorological measurements (June 2008 to May 2015) at a remote background site of the eastern Mediterranean were recorded and analyzed to assess the impact of NPF (of 162 episodes identified) on CCN and cloud droplet number concentration (CDNC) formation in the region. A new metric is introduced to quantitatively determine the initiation and duration of the influence of NPF on the CCN spectrum. NPF days were found to increase CCN concentrations (from 0.10 % to 1.00 % supersaturation) between 29 % and 77 %. Enhanced CCN concentrations from NPF are mostly observed, as expected, under low preexisting particle concentrations and occur in the afternoon, relatively later in the winter and autumn than in the summer. Potential impacts of NPF on cloud formation were quantified by introducing the observed aerosol size distributions and chemical composition into an established cloud droplet parameterization. We find that the supersaturations that develop are very low (ranging between 0.03 % and 0.27 %) for typical boundary layer dynamics (σw ∼0.3 m s−1) and NPF is found to enhance CDNC by a modest 13 %. This considerable contrast between CCN and CDNC response is in part from the different supersaturation levels considered, but also because supersaturation drops from increasing CCN because of water vapor competition effects during the process of droplet formation. The low cloud supersaturation further delays the appearance of NPF impacts on CDNC to clouds formed in the late evening and nighttime – which has important implications for the extent and types of indirect effects induced by NPF events. An analysis based on CCN concentrations using prescribed supersaturation can provide very different, even misleading, conclusions and should therefore be avoided. The proposed approach here offers a simple, yet highly effective way for a more realistic impact assessment of NPF events on cloud formation.
Panayiotis Kalkavouras; Aikaterini Bougiatioti; Nikos Kalivitis; Iasonas Stavroulas; Maria Tombrou-Tzella; Athanasios Nenes; Nikolaos Mihalopoulos. Regional new particle formation as modulators of cloud condensation nuclei and cloud droplet number in the eastern Mediterranean. Atmospheric Chemistry and Physics 2019, 19, 6185 -6203.
AMA StylePanayiotis Kalkavouras, Aikaterini Bougiatioti, Nikos Kalivitis, Iasonas Stavroulas, Maria Tombrou-Tzella, Athanasios Nenes, Nikolaos Mihalopoulos. Regional new particle formation as modulators of cloud condensation nuclei and cloud droplet number in the eastern Mediterranean. Atmospheric Chemistry and Physics. 2019; 19 (9):6185-6203.
Chicago/Turabian StylePanayiotis Kalkavouras; Aikaterini Bougiatioti; Nikos Kalivitis; Iasonas Stavroulas; Maria Tombrou-Tzella; Athanasios Nenes; Nikolaos Mihalopoulos. 2019. "Regional new particle formation as modulators of cloud condensation nuclei and cloud droplet number in the eastern Mediterranean." Atmospheric Chemistry and Physics 19, no. 9: 6185-6203.
Atmospheric new particle formation (NPF) is a common phenomenon all over the world. In this study we present the longest time series of NPF records in the eastern Mediterranean region by analyzing 10 years of aerosol number size distribution data obtained with a mobility particle sizer. The measurements were performed at the Finokalia environmental research station on Crete, Greece, during the period June 2008–June 2018. We found that NPF took place on 27 % of the available days, undefined days were 23 % and non-event days 50 %. NPF is more frequent in April and May probably due to the terrestrial biogenic activity and is less frequent in August. Throughout the period under study, nucleation was observed also during the night. Nucleation mode particles had the highest concentration in winter and early spring, mainly because of the minimum sinks, and their average contribution to the total particle number concentration was 8 %. Nucleation mode particle concentrations were low outside periods of active NPF and growth, so there are hardly any other local sources of sub-25 nm particles. Additional atmospheric ion size distribution data simultaneously collected for more than 2 years were also analyzed. Classification of NPF events based on ion spectrometer measurements differed from the corresponding classification based on a mobility spectrometer, possibly indicating a different representation of local and regional NPF events between these two measurement data sets. We used the MALTE-Box model for simulating a case study of NPF in the eastern Mediterranean region. Monoterpenes contributing to NPF can explain a large fraction of the observed NPF events according to our model simulations. However the adjusted parameterization resulting from our sensitivity tests was significantly different from the initial one that had been determined for the boreal environment.
Nikos Kalivitis; Veli-Matti Kerminen; Giorgos Kouvarakis; Iasonas Stavroulas; Evaggelia Tzitzikalaki; Panayiotis Kalkavouras; Nikos Daskalakis; Stelios Myriokefalitakis; Aikaterini Bougiatioti; Hanna E. Manninen; Pontus Roldin; Tuukka Petäjä; Michael Boy; Markku Kulmala; Maria Kanakidou; Nikolaos Mihalopoulos. Formation and growth of atmospheric nanoparticles in the eastern Mediterranean: results from long-term measurements and process simulations. Atmospheric Chemistry and Physics 2019, 19, 2671 -2686.
AMA StyleNikos Kalivitis, Veli-Matti Kerminen, Giorgos Kouvarakis, Iasonas Stavroulas, Evaggelia Tzitzikalaki, Panayiotis Kalkavouras, Nikos Daskalakis, Stelios Myriokefalitakis, Aikaterini Bougiatioti, Hanna E. Manninen, Pontus Roldin, Tuukka Petäjä, Michael Boy, Markku Kulmala, Maria Kanakidou, Nikolaos Mihalopoulos. Formation and growth of atmospheric nanoparticles in the eastern Mediterranean: results from long-term measurements and process simulations. Atmospheric Chemistry and Physics. 2019; 19 (4):2671-2686.
Chicago/Turabian StyleNikos Kalivitis; Veli-Matti Kerminen; Giorgos Kouvarakis; Iasonas Stavroulas; Evaggelia Tzitzikalaki; Panayiotis Kalkavouras; Nikos Daskalakis; Stelios Myriokefalitakis; Aikaterini Bougiatioti; Hanna E. Manninen; Pontus Roldin; Tuukka Petäjä; Michael Boy; Markku Kulmala; Maria Kanakidou; Nikolaos Mihalopoulos. 2019. "Formation and growth of atmospheric nanoparticles in the eastern Mediterranean: results from long-term measurements and process simulations." Atmospheric Chemistry and Physics 19, no. 4: 2671-2686.
Submicron aerosol chemical composition was studied during a year-long period (26 July 2016–31 July 2017) and two wintertime intensive campaigns (18 December 2013–21 February 2014 and 23 December 2015–17 February 2016), at a central site in Athens, Greece, using an Aerosol Chemical Speciation Monitor (ACSM). Concurrent measurements included a particle-into-liquid sampler (PILS-IC), a scanning mobility particle sizer (SMPS), an AE-33 Aethalometer, and ion chromatography analysis on 24 or 12 h filter samples. The aim of the study was to characterize the seasonal variability of the main submicron aerosol constituents and decipher the sources of organic aerosol (OA). Organics were found to contribute almost half of the submicron mass, with 30 min resolution concentrations during wintertime reaching up to 200 µg m−3. During winter (all three campaigns combined), primary sources contributed about 33 % of the organic fraction, and comprised biomass burning (10 %), fossil fuel combustion (13 %), and cooking (10 %), while the remaining 67 % was attributed to secondary aerosol. The semi-volatile component of the oxidized organic aerosol (SV-OOA; 22 %) was found to be clearly linked to combustion sources, in particular biomass burning; part of the very oxidized, low-volatility component (LV-OOA; 44 %) could also be attributed to the oxidation of emissions from these primary combustion sources. These results, based on the combined contribution of biomass burning organic aerosol (BBOA) and SV-OOA, indicate the importance of increased biomass burning in the urban environment of Athens as a result of the economic recession. During summer, when concentrations of fine aerosols are considerably lower, more than 80 % of the organic fraction is attributed to secondary aerosol (SV-OOA 31 % and LV-OOA 53 %). In contrast to winter, SV-OOA appears to result from a well-mixed type of aerosol that is linked to fast photochemical processes and the oxidation of primary traffic and biogenic emissions. Finally, LV-OOA presents a more regional character in summer, owing to the oxidation of OA over the period of a few days.
Iasonas Stavroulas; Aikaterini Bougiatioti; Georgios Grivas; Despina Paraskevopoulou; Maria Tsagkaraki; Pavlos Zarmpas; Eleni Liakakou; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. Sources and processes that control the submicron organic aerosol composition in an urban Mediterranean environment (Athens): a high temporal-resolution chemical composition measurement study. Atmospheric Chemistry and Physics 2019, 19, 901 -919.
AMA StyleIasonas Stavroulas, Aikaterini Bougiatioti, Georgios Grivas, Despina Paraskevopoulou, Maria Tsagkaraki, Pavlos Zarmpas, Eleni Liakakou, Evangelos Gerasopoulos, Nikolaos Mihalopoulos. Sources and processes that control the submicron organic aerosol composition in an urban Mediterranean environment (Athens): a high temporal-resolution chemical composition measurement study. Atmospheric Chemistry and Physics. 2019; 19 (2):901-919.
Chicago/Turabian StyleIasonas Stavroulas; Aikaterini Bougiatioti; Georgios Grivas; Despina Paraskevopoulou; Maria Tsagkaraki; Pavlos Zarmpas; Eleni Liakakou; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. 2019. "Sources and processes that control the submicron organic aerosol composition in an urban Mediterranean environment (Athens): a high temporal-resolution chemical composition measurement study." Atmospheric Chemistry and Physics 19, no. 2: 901-919.