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A satellite algorithm able to identify Dust Aerosols (DA) is applied for a climatological investigation of Dust Aerosol Episodes (DAEs) over the greater Mediterranean Basin (MB), one of the most climatologically sensitive regions of the globe. The algorithm first distinguishes DA among other aerosol types (such as Sea Salt and Biomass Burning) by applying threshold values on key aerosol optical properties describing their loading, size and absorptivity, namely Aerosol Optical Depth (AOD), Aerosol Index (AI) and Ångström Exponent (α). The algorithm operates on a daily and 1° × 1° geographical cell basis over the 15-year period 2005–2019. Daily gridded spectral AOD data are taken from Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua Collection 6.1, and are used to calculate the α data, which are then introduced into the algorithm, while AI data are obtained by the Ozone Monitoring Instrument (OMI) -Aura- Near-UV aerosol product OMAERUV dataset. The algorithm determines the occurrence of Dust Aerosol Episode Days (DAEDs), whenever high loads of DA (higher than their climatological mean value plus two/four standard deviations for strong/extreme DAEDs) exist over extended areas (more than 30 pixels or 300,000 km2). The identified DAEDs are finally grouped into Dust Aerosol Episode Cases (DAECs), consisting of at least one DAED. According to the algorithm results, 166 (116 strong and 50 extreme) DAEDs occurred over the MB during the study period. DAEDs are observed mostly in spring (47%) and summer (38%), with strong DAEDs occurring primarily in spring and summer and extreme ones in spring. Decreasing, but not statistically significant, trends of the frequency, spatial extent and intensity of DAECs are revealed. Moreover, a total number of 98 DAECs was found, primarily in spring (46 DAECs) and secondarily in summer (36 DAECs). The seasonal distribution of the frequency of DAECs varies geographically, being highest in early spring over the eastern Mediterranean, in late spring over the central Mediterranean and in summer over the western MB.
Maria Gavrouzou; Nikolaos Hatzianastassiou; Antonis Gkikas; Christos Lolis; Nikolaos Mihalopoulos. A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data. Remote Sensing 2021, 13, 2895 .
AMA StyleMaria Gavrouzou, Nikolaos Hatzianastassiou, Antonis Gkikas, Christos Lolis, Nikolaos Mihalopoulos. A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data. Remote Sensing. 2021; 13 (15):2895.
Chicago/Turabian StyleMaria Gavrouzou; Nikolaos Hatzianastassiou; Antonis Gkikas; Christos Lolis; Nikolaos Mihalopoulos. 2021. "A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data." Remote Sensing 13, no. 15: 2895.
Atmospheric-chemical coupled models usually parameterize sea-salt aerosol (SSA) emissions using whitecap fraction estimated considering only wind speed and ignoring sea state. This approach may introduce inaccuracies in SSA simulation. This study aims to assess the impact of sea state on SSA modeling, applying a new parameterization for whitecap fraction estimation based on wave age, calculated by the ratio between wave phase velocity and wind speed. To this end, the new parameterization was incorporated in the coupled Chemical Hydrological Atmospheric Ocean wave modeling System (CHAOS). CHAOS encompasses the wave model (WAM) two-way coupled through the OASIS3-MCT coupler with the Advanced Weather Research and Forecasting model coupled with Chemistry (WRF-ARW-Chem) and, thus, enabling the concurrent simulation of SSAs, wind speed and wave phase velocity. The simulation results were evaluated against in-situ and lidar measurements at 2 stations in Greece (Finokalia on 4 and 15 July 2014 and Antikythera-PANGEA on 15 September 2018). The results reveal significant differences between the parameterizations with the new one offering a more realistic representation of SSA levels in some layers of the lower atmosphere. This is attributed to the enhancement of the bubble-bursting mechanism representation with air-sea processes controlling whitecap fraction. Our findings also highlight the contribution of fresh wind-generated waves to SSA modeling.
George Varlas; Eleni Marinou; Anna Gialitaki; Nikolaos Siomos; Konstantinos Tsarpalis; Nikolaos Kalivitis; Stavros Solomos; Alexandra Tsekeri; Christos Spyrou; Maria Tsichla; Anna Kampouri; Vassilis Vervatis; Elina Giannakaki; Vassilis Amiridis; Nikolaos Mihalopoulos; Anastasios Papadopoulos; Petros Katsafados. Assessing Sea-State Effects on Sea-Salt Aerosol Modeling in the Lower Atmosphere Using Lidar and In-Situ Measurements. Remote Sensing 2021, 13, 614 .
AMA StyleGeorge Varlas, Eleni Marinou, Anna Gialitaki, Nikolaos Siomos, Konstantinos Tsarpalis, Nikolaos Kalivitis, Stavros Solomos, Alexandra Tsekeri, Christos Spyrou, Maria Tsichla, Anna Kampouri, Vassilis Vervatis, Elina Giannakaki, Vassilis Amiridis, Nikolaos Mihalopoulos, Anastasios Papadopoulos, Petros Katsafados. Assessing Sea-State Effects on Sea-Salt Aerosol Modeling in the Lower Atmosphere Using Lidar and In-Situ Measurements. Remote Sensing. 2021; 13 (4):614.
Chicago/Turabian StyleGeorge Varlas; Eleni Marinou; Anna Gialitaki; Nikolaos Siomos; Konstantinos Tsarpalis; Nikolaos Kalivitis; Stavros Solomos; Alexandra Tsekeri; Christos Spyrou; Maria Tsichla; Anna Kampouri; Vassilis Vervatis; Elina Giannakaki; Vassilis Amiridis; Nikolaos Mihalopoulos; Anastasios Papadopoulos; Petros Katsafados. 2021. "Assessing Sea-State Effects on Sea-Salt Aerosol Modeling in the Lower Atmosphere Using Lidar and In-Situ Measurements." Remote Sensing 13, no. 4: 614.
COVID-19 is evolving into one of the worst pandemics in recent history, claiming a death toll of over 1.5 million as of December 2020. In an attempt to limit the expansion of the pandemic in its initial phase, nearly all countries imposed restriction measures, which resulted in an unprecedented reduction of air pollution. This study aims to assess the impact of the lockdown effects due to COVID-19 on in situ measured aerosol properties, namely spectral-scattering (bsca) and absorption (babs) coefficients, black carbon (BC) concentrations, single-scattering albedo (SSA), scattering and absorption Ångström exponents (SAE, AAE) in Athens, Greece. Moreover, a comparison is performed with the regional background site of Finokalia, Crete, for a better assessment of the urban impact on observed differences. The study examines pre-lockdown (1–22 March 2020), lockdown (23 March–3 May 2020) and post-lockdown (4–31 May 2020) periods, while the aerosol properties are also compared with a 3–4 year preceding period (2016/2017–2019). Comparison of meteorological parameters in Athens, between the lockdown period and respective days in previous years, showed only marginal variation, which is not deemed sufficient in order to justify the notable changes in aerosol concentrations and optical properties. The largest reduction during the lockdown period was observed for babs compared to the pre-lockdown (−39%) and to the same period in previous years (−36%). This was intensified during the morning traffic hours (−60%), reflecting the large decrease in vehicular emissions. Furthermore, AAE increased during the lockdown period due to reduced emissions from fossil-fuel combustion, while a smaller (−21%) decrease was observed for bsca along with slight increases (6%) in SAE and SSA values, indicating that scattering aerosol properties were less affected by the decrease in vehicular emissions, as they are more dependent on regional sources and atmospheric processing. Nighttime BC emissions related to residential wood-burning were slightly increased during the lockdown period, with respect to previous-year means. On the contrary, aerosol and pollution changes during the lockdown period at Finokalia were low and highly sensitive to natural sources and processes.
Dimitris Kaskaoutis; Georgios Grivas; Eleni Liakakou; Nikos Kalivitis; Giorgos Kouvarakis; Iasonas Stavroulas; Panayiotis Kalkavouras; Pavlos Zarmpas; Umesh Dumka; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece. Atmosphere 2021, 12, 231 .
AMA StyleDimitris Kaskaoutis, Georgios Grivas, Eleni Liakakou, Nikos Kalivitis, Giorgos Kouvarakis, Iasonas Stavroulas, Panayiotis Kalkavouras, Pavlos Zarmpas, Umesh Dumka, Evangelos Gerasopoulos, Nikolaos Mihalopoulos. Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece. Atmosphere. 2021; 12 (2):231.
Chicago/Turabian StyleDimitris Kaskaoutis; Georgios Grivas; Eleni Liakakou; Nikos Kalivitis; Giorgos Kouvarakis; Iasonas Stavroulas; Panayiotis Kalkavouras; Pavlos Zarmpas; Umesh Dumka; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. 2021. "Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece." Atmosphere 12, no. 2: 231.
A satellite-based algorithm is developed and used to determine the presence of dust aerosols on a global scale. The algorithm uses as input aerosol optical properties from the MOderate Resolution Imaging Spectroradiometer (MODIS)-Aqua Collection 6.1 and Ozone Monitoring Instrument (OMI)-Aura version v003 (OMAER-UV) datasets and identifies the existence of dust aerosols in the atmosphere by applying specific thresholds, which ensure the coarse size and the absorptivity of dust aerosols, on the input optical properties. The utilized aerosol optical properties are the multiwavelength aerosol optical depth (AOD), the Aerosol Absorption Index (AI) and the Ångström Exponent (a). The algorithm operates on a daily basis and at 1° × 1° latitude-longitude spatial resolution for the period 2005–2019 and computes the absolute and relative frequency of the occurrence of dust. The monthly and annual mean frequencies are calculated on a pixel level for each year of the study period, enabling the study of the seasonal as well as the inter-annual variation of dust aerosols’ occurrence all over the globe. Temporal averaging is also applied to the annual values in order to estimate the 15-year climatological mean values. Apart from temporal, a spatial averaging is also applied for the entire globe as well as for specific regions of interest, namely great global deserts and areas of desert dust export. According to the algorithm results, the highest frequencies of dust occurrence (up to 160 days/year) are primarily observed over the western part of North Africa (Sahara), and over the broader area of Bodélé, and secondarily over the Asian Taklamakan desert (140 days/year). For most of the study regions, the maximum frequencies appear in boreal spring and/or summer and the minimum ones in winter or autumn. A clear seasonality of global dust is revealed, with the lowest frequencies in November–December and the highest ones in June. Finally, an increasing trend of global dust frequency of occurrence from 2005 to 2019, equal to 56.2%, is also found. Such an increasing trend is observed over all study regions except for North Middle East, where a slight decreasing trend (−2.4%) is found.
Maria Gavrouzou; Nikolaos Hatzianastassiou; Antonis Gkikas; Marios-Bruno Korras-Carraca; Nikolaos Mihalopoulos. A Global Climatology of Dust Aerosols Based on Satellite Data: Spatial, Seasonal and Inter-Annual Patterns over the Period 2005–2019. Remote Sensing 2021, 13, 359 .
AMA StyleMaria Gavrouzou, Nikolaos Hatzianastassiou, Antonis Gkikas, Marios-Bruno Korras-Carraca, Nikolaos Mihalopoulos. A Global Climatology of Dust Aerosols Based on Satellite Data: Spatial, Seasonal and Inter-Annual Patterns over the Period 2005–2019. Remote Sensing. 2021; 13 (3):359.
Chicago/Turabian StyleMaria Gavrouzou; Nikolaos Hatzianastassiou; Antonis Gkikas; Marios-Bruno Korras-Carraca; Nikolaos Mihalopoulos. 2021. "A Global Climatology of Dust Aerosols Based on Satellite Data: Spatial, Seasonal and Inter-Annual Patterns over the Period 2005–2019." Remote Sensing 13, no. 3: 359.
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.
This study aims to characterize the variability and sources of water-soluble organic nitrogen (WSON) in aerosol over Cyprus in the Eastern Mediterranean. Measurements of PM10 particles were conducted during the calendar year of 2011 at two sites, located at a roadside location in Nicosia (urban traffic) and in the rural area of Agia Marina Xyliatou (regional background). Filter samples were analyzed for water-soluble total nitrogen (WSTN), nitrate and ammonium, to determine WSON. Additional analyses were performed, for water-soluble organic carbon (WSOC), organic and elemental carbon (OC and EC), major ions and trace metals. Annual mean WSON concentrations of 0.20 and 0.16 μgN m−3 were determined at the urban traffic and regional background sites, respectively. The organic fraction of WSTN was about 20%, with limited inter-site and seasonal variability. Distinct seasonal patterns were observed at the two sites, with warm-period concentrations being significantly higher at the regional background site, while the enhanced local emissions during winter at the traffic site smoothed out the observed variability. Mean WSON/WSOC ratios of 0.09–0.12 were calculated at the two sites, with the two parameters being weakly correlated. A roadside WSON enhancement was verified, although moderate on an annual basis (9%). However, concentrations in Nicosia were more than one time higher than the background during winter. The observed temporal and inter-site variability highlighted the necessity of source apportionment, which was performed using Positive Matrix Factorization (PMF) modeling, utilizing the analytical datasets at the two sites. In this way, the estimated contribution of regional transport of processed aerosols was found to be more pronounced at the regional background site (59% vs. 38%), while a sizeable input (35%) was linked to vehicular emissions at the traffic site. An additional anthropogenic impact, probably related to biomass burning, was estimated at both sites (16%), while contributions of natural sources like mineral dust (4–8%) and marine aerosol (2–3%) were smaller.
Maria Tsagkaraki; Christina Theodosi; Georgios Grivas; Evanthia Vargiakaki; Jean Sciare; Chrysanthos Savvides; Nikolaos Mihalopoulos. Spatiotemporal variability and sources of aerosol water-soluble organic nitrogen (WSON), in the Eastern Mediterranean. Atmospheric Environment 2020, 246, 118144 .
AMA StyleMaria Tsagkaraki, Christina Theodosi, Georgios Grivas, Evanthia Vargiakaki, Jean Sciare, Chrysanthos Savvides, Nikolaos Mihalopoulos. Spatiotemporal variability and sources of aerosol water-soluble organic nitrogen (WSON), in the Eastern Mediterranean. Atmospheric Environment. 2020; 246 ():118144.
Chicago/Turabian StyleMaria Tsagkaraki; Christina Theodosi; Georgios Grivas; Evanthia Vargiakaki; Jean Sciare; Chrysanthos Savvides; Nikolaos Mihalopoulos. 2020. "Spatiotemporal variability and sources of aerosol water-soluble organic nitrogen (WSON), in the Eastern Mediterranean." Atmospheric Environment 246, no. : 118144.
Airborne sub-micrometer particles (PM1) have been documented to exert adverse impacts on human health, including respiratory and cardiovascular disease and premature mortality. The Greater Athens Area (GAA), characterized by topographic and meteorological conditions which frequently obstruct the effective dispersion of ambient pollutants, hosts approximately 40% of Greece’s population. It can be considered an “ambient laboratory” for studying PM1 pollution events, given the intensity and diversity of submicron aerosol sources and processing. Fine aerosol chemical composition is continuously monitored at the National Observatory of Athens Air Monitoring Station in Thissio, an urban background site in Central Athens. Furthermore, two intensive monthly campaigns were held at a central site in Piraeus, where Greece’s busiest passenger port is located, during both winter (December 2018–January 2019) and summer (June–July 2019) periods. Organic aerosol (OA), sulfate, nitrate, ammonium, and chloride were measured using an aerosol chemical speciation monitor (ACSM), while black carbon (BC and source-specific components) was measured using a multi-wavelength aethalometer (AE-33). The variability of concentrations at different temporal scales was examined, revealing differences for primary aerosol components, depending on site type and location, and related to local sources and transport processes. Biomass burning for domestic heating was found to be a key factor during wintertime, leading to uniform OA and BC levels at both sites, while the local sources in Piraeus (traffic, port activity) lead to substantially increased levels during the summer. Secondary sources were found to affect both sites in a relatively homogeneous manner.
Iasonas Stavroulas; Georgios Grivas; Nikolaos Mihalopoulos. Spatial Characteristics of PM1 Aerosol Chemical Composition over the Greater Athens Area. Environmental Sciences Proceedings 2020, 4, 7 .
AMA StyleIasonas Stavroulas, Georgios Grivas, Nikolaos Mihalopoulos. Spatial Characteristics of PM1 Aerosol Chemical Composition over the Greater Athens Area. Environmental Sciences Proceedings. 2020; 4 (1):7.
Chicago/Turabian StyleIasonas Stavroulas; Georgios Grivas; Nikolaos Mihalopoulos. 2020. "Spatial Characteristics of PM1 Aerosol Chemical Composition over the Greater Athens Area." Environmental Sciences Proceedings 4, no. 1: 7.
In the present study, dust aerosol episodes (DAEs) in the broader Mediterranean Basin (MB) are investigated over a 15-year (2005–2019) period using contemporary MODIS Collection 6.1 and OMI OMAERUV satellite data and a satellite algorithm applying a thresholding technique on selected aerosol optical properties. The algorithm operates on a daily and 1° × 1° pixel level basis, first identifying the presence of dust, and consequently requiring the presence of unusually high dust loads, i.e., dust episodes. Apart from the presence of pixel-level DAEs, an extended spatial coverage of dust is also required. Thus, a specific day is characterized as a Dust Aerosol Episode Day (DAED), when at least 30 episodic pixels exist over Mediterranean Basin (MB). According to the algorithm results, 166 DAEDs (116 strong and 50 extreme) took place in the MB from 2005 to 2019. Most DAEDs occurred in spring (47%) and summer (38%), while a different seasonality is observed for strong and extreme episodes. The interannual variability of DAEDs reveal a decreasing trend, which is however not statistically significant.
Maria Gavrouzou; Nikos Hatzianastassiou; Antonis Gkikas; Nikos Mihalopoulos. A 15-Year Climatology of Desert Dust Episodes in the Broader Mediterranean Basin. Environmental Sciences Proceedings 2020, 4, 1 .
AMA StyleMaria Gavrouzou, Nikos Hatzianastassiou, Antonis Gkikas, Nikos Mihalopoulos. A 15-Year Climatology of Desert Dust Episodes in the Broader Mediterranean Basin. Environmental Sciences Proceedings. 2020; 4 (1):1.
Chicago/Turabian StyleMaria Gavrouzou; Nikos Hatzianastassiou; Antonis Gkikas; Nikos Mihalopoulos. 2020. "A 15-Year Climatology of Desert Dust Episodes in the Broader Mediterranean Basin." Environmental Sciences Proceedings 4, no. 1: 1.
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.
In this study, the performance and characteristics of the advanced cloud nucleation scheme of Fountoukis and Nenes, embedded in the fully coupled Weather Research and Forecasting/Chemistry (WRF/Chem) model, are investigated. Furthermore, the impact of dust particles on the distribution of the cloud condensation nuclei (CCN) and the way they modify the pattern of the precipitation are also examined. For the simulation of dust particle concentration, the Georgia Tech Goddard Global Ozone Chemistry Aerosol Radiation and Transport of Air Force Weather Agency (GOCART-AFWA) is used as it includes components for the representation of dust emission and transport. The aerosol activation parameterization scheme of Fountoukis and Nenes has been implemented in the six-class WRF double-moment (WDM6) microphysics scheme, which treats the CCN distribution as a prognostic variable, but does not take into account the concentration of dust aerosols. Additionally, the presence of dust particles that may facilitate the activation of CCN into cloud or rain droplets has also been incorporated in the cumulus scheme of Grell and Freitas. The embedded scheme is assessed through a case study of significant dust advection over the Western Mediterranean, characterized by severe rainfall. Inclusion of CCN based on prognostic dust particles leads to the suppression of precipitation over hazy areas. On the contrary, precipitation is enhanced over areas away from the dust event. The new prognostic CCN distribution improves in general the forecasting skill of the model as bias scores, the root mean square error (RMSE), false alarm ratio (FAR) and frequencies of missed forecasts (FOM) are limited when modelled data are compared against satellite, LIDAR and aircraft observations.
Konstantinos Tsarpalis; Petros Katsafados; Anastasios Papadopoulos; Nikolaos Mihalopoulos. Assessing Desert Dust Indirect Effects on Cloud Microphysics through a Cloud Nucleation Scheme: A Case Study over the Western Mediterranean. Remote Sensing 2020, 12, 3473 .
AMA StyleKonstantinos Tsarpalis, Petros Katsafados, Anastasios Papadopoulos, Nikolaos Mihalopoulos. Assessing Desert Dust Indirect Effects on Cloud Microphysics through a Cloud Nucleation Scheme: A Case Study over the Western Mediterranean. Remote Sensing. 2020; 12 (21):3473.
Chicago/Turabian StyleKonstantinos Tsarpalis; Petros Katsafados; Anastasios Papadopoulos; Nikolaos Mihalopoulos. 2020. "Assessing Desert Dust Indirect Effects on Cloud Microphysics through a Cloud Nucleation Scheme: A Case Study over the Western Mediterranean." Remote Sensing 12, no. 21: 3473.
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.
The role of the atmosphere as an external source of various nutrients and elements of both natural and anthropogenic origin in the Eastern Mediterranean and in particular the Aegean Sea has been investigated by using long-term deposition data collected over a 21-year period at Finokalia, Crete, Greece. Dry deposition was found to be the main mechanism contributing 67% of total insoluble matter flux, 68% of total dissolved inorganic nitrogen (DIN) flux, and 75% of total dissolved inorganic P (DIP) flux. Sediment traps data from 200 sinking particulate matter samples collected at 2 different depths in the seawater column (500 m and 1715 m) in the Cretan Sea (southern Aegean Sea) during a 9-year period (1997–2005) were compared with atmospheric deposition data (simultaneously collected) to assess the role of atmospheric deposition on seawater productivity and mass transfer in the seawater column. Atmospheric deposition was found to play a significant role in seawater productivity of the Aegean Sea by providing essential nutrients and especially N in excess and by facilitating the creation of aggregates between atmospheric dust and biological material and thus influencing their mass transfer to deeper waters by increasing their size and settling velocity.
Maria Tsagkaraki; Christina Theodosi; Maria Kanakidou; Nikos Mihalopoulos. Atmospheric Deposition over the Aegean Sea and Its Impact on the Seawater Productivity. The Handbook of Environmental Chemistry 2020, 1 -21.
AMA StyleMaria Tsagkaraki, Christina Theodosi, Maria Kanakidou, Nikos Mihalopoulos. Atmospheric Deposition over the Aegean Sea and Its Impact on the Seawater Productivity. The Handbook of Environmental Chemistry. 2020; ():1-21.
Chicago/Turabian StyleMaria Tsagkaraki; Christina Theodosi; Maria Kanakidou; Nikos Mihalopoulos. 2020. "Atmospheric Deposition over the Aegean Sea and Its Impact on the Seawater Productivity." The Handbook of Environmental Chemistry , no. : 1-21.
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.
Monoterpenes and isoprene are important constituents of the volatile organic compounds (VOCs) due to their high reactivity and participation in ozone and secondary aerosol formation. The current work focuses on the results of a 13-month intensive campaign of high resolution time-resolved measurements of these compounds, at an urban background site in Athens, Greece. On an annual basis, monoterpenes (α-pinene and limonene) surpass the isoprene levels presenting mean values of 0.70 ± 0.83 μg m−3, 0.33 ± 0.78 μg m−3 and 0.19 ± 0.36 μg m−3, respectively. The large standard deviation highlights the significant diurnal and day-to-day variability. Isoprene presents a typical seasonal cycle, with a photochemically induced summer-time maximum. Enhanced noon levels are observed during summer, whereas a morning peak in the autumn and winter profiles occurs, despite the generally low levels encountered during these seasons. The monoterpenes deviate from the expected biogenic pattern, presenting higher mean levels during the cold period and a night-to-early morning enhancement strongly related to local anthropogenic tracers such as BC, CO, NO or toluene, as well as increased levels under wind speeds lower than 3 m s−1. Estimations of the anthropogenic and biogenic fractions based on the enhancement ratios of α-pinene versus a variety of anthropogenic tracers, demonstrate a clear dominance of the anthropogenic sources in all studied seasons. Simultaneously, the biogenic fraction increased during summer relative to winter by more than 10 times. Both α-pinene and limonene significantly contribute to locally formed secondary organic aerosol (SOA), determined by means of an ACSM, accounting for at least 22% and 13% of their levels in summer and winter respectively. Additionally, monoterpenes and isoprene contribute 6% to the observed oxidants levels (O3 + NOx) during summer.
Anastasia Panopoulou; Eleni Liakakou; Stéphane Sauvage; Valérie Gros; Nadine Locoge; Iasonas Stavroulas; Bernard Bonsang; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. Yearlong measurements of monoterpenes and isoprene in a Mediterranean city (Athens): Natural vs anthropogenic origin. Atmospheric Environment 2020, 243, 117803 .
AMA StyleAnastasia Panopoulou, Eleni Liakakou, Stéphane Sauvage, Valérie Gros, Nadine Locoge, Iasonas Stavroulas, Bernard Bonsang, Evangelos Gerasopoulos, Nikolaos Mihalopoulos. Yearlong measurements of monoterpenes and isoprene in a Mediterranean city (Athens): Natural vs anthropogenic origin. Atmospheric Environment. 2020; 243 ():117803.
Chicago/Turabian StyleAnastasia Panopoulou; Eleni Liakakou; Stéphane Sauvage; Valérie Gros; Nadine Locoge; Iasonas Stavroulas; Bernard Bonsang; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. 2020. "Yearlong measurements of monoterpenes and isoprene in a Mediterranean city (Athens): Natural vs anthropogenic origin." Atmospheric Environment 243, no. : 117803.
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 examines the carbonaceous-aerosol characteristics at three contrasting urban environments in Greece (Ioannina, Athens, and Heraklion), on the basis of 12 h sampling during winter (January to February 2013), aiming to explore the inter-site differences in atmospheric composition and carbonaceous-aerosol characteristics and sources. The winter-average organic carbon (OC) and elemental carbon (EC) concentrations in Ioannina were found to be 28.50 and 4.33 µg m−3, respectively, much higher than those in Heraklion (3.86 µg m−3 for OC and 2.29 µg m−3 for EC) and Athens (7.63 µg m−3 for OC and 2.44 µg m−3 for EC). The winter OC/EC ratio in Ioannina (6.53) was found to be almost three times that in Heraklion (2.03), indicating a larger impact of wood combustion, especially during the night, whereas in Heraklion, emissions from biomass burning were found to be less intense. Estimations of primary and secondary organic carbon (POC and SOC) using the EC-tracer method, and specifically its minimum R-squared (MRS) variant, revealed large differences between the sites, with a prevalence of POC (67–80%) in Ioannina and Athens and with a larger SOC fraction (53%) in Heraklion. SOC estimates were also obtained using the 5% and 25% percentiles of the OC/EC data to determine the (OC/EC)pri, leading to results contrasting to the MRS approach in Ioannina (70–74% for SOC). Although the MRS method provides generally more robust results, it may significantly underestimate SOC levels in environments highly burdened by biomass burning, as the fast-oxidized semi-volatile OC associated with combustion sources is classified in POC. Further analysis in Athens revealed that the difference in SOC estimates between the 5% percentile and MRS methods coincided with the semi-volatile oxygenated organic aerosol as quantified by aerosol mass spectrometry. Finally, the OC/Kbb+ ratio was used as tracer for decomposition of the POC into fossil-fuel and biomass-burning components, indicating the prevalence of biomass-burning POC, especially in Ioannina (77%).
Dimitris G. Kaskaoutis; Georgios Grivas; Christina Theodosi; Maria Tsagkaraki; Despina Paraskevopoulou; Iasonas Stavroulas; Eleni Liakakou; Antonis Gkikas; Nikolaos Hatzianastassiou; Cheng Wu; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. Carbonaceous Aerosols in Contrasting Atmospheric Environments in Greek Cities: Evaluation of the EC-tracer Methods for Secondary Organic Carbon Estimation. Atmosphere 2020, 11, 161 .
AMA StyleDimitris G. Kaskaoutis, Georgios Grivas, Christina Theodosi, Maria Tsagkaraki, Despina Paraskevopoulou, Iasonas Stavroulas, Eleni Liakakou, Antonis Gkikas, Nikolaos Hatzianastassiou, Cheng Wu, Evangelos Gerasopoulos, Nikolaos Mihalopoulos. Carbonaceous Aerosols in Contrasting Atmospheric Environments in Greek Cities: Evaluation of the EC-tracer Methods for Secondary Organic Carbon Estimation. Atmosphere. 2020; 11 (2):161.
Chicago/Turabian StyleDimitris G. Kaskaoutis; Georgios Grivas; Christina Theodosi; Maria Tsagkaraki; Despina Paraskevopoulou; Iasonas Stavroulas; Eleni Liakakou; Antonis Gkikas; Nikolaos Hatzianastassiou; Cheng Wu; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. 2020. "Carbonaceous Aerosols in Contrasting Atmospheric Environments in Greek Cities: Evaluation of the EC-tracer Methods for Secondary Organic Carbon Estimation." Atmosphere 11, no. 2: 161.
Long-term ground-based measurements of aerosol optical properties in Athens, Greece, for the period 2008–2018 performed by the National Observatory of Athens are used in order to investigate the aerosol climatology of the area. In this study, we utilize quality-assured measurements of the aerosol optical depth (AOD), Single Scattering Albedo (SSA) and Ångström exponent obtained by CIMEL photometers in the framework of the Aerosol Robotic Network (AERONET) to extract the seasonality and the trends of aerosols in the region. Higher aerosol loads are found during spring and summer months. A 1.1% per year decrease for AOD at 440 nm and 0.4% decrease per year for SSA during the studied period are recorded. Collocated and synchronous PM10 values, for a five-year period, are used in order to study ground-level conditions. Also, the Planetary Boundary Layer Height from ERA-5 is used to investigate the stratification of the particles. The classification of aerosols using AERONET data is performed to separate dust, biomass burning, polluted urban, marine and continental dominant aerosol mixtures. Also, the characterization of AOD provided by Copernicus Atmosphere Monitoring Service (CAMS) is investigated. Finally, seasonal AOD trends recorded from AERONET from satellite sensors (MODIS-Aqua/MODIS-Terra) and estimated by CAMS are examined, and significant differences have been found.
Ioannis-Panagiotis Raptis; Stelios Kazadzis; Vassilis Amiridis; Antonis Gkikas; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. A Decade of Aerosol Optical Properties Measurements over Athens, Greece. Atmosphere 2020, 11, 154 .
AMA StyleIoannis-Panagiotis Raptis, Stelios Kazadzis, Vassilis Amiridis, Antonis Gkikas, Evangelos Gerasopoulos, Nikolaos Mihalopoulos. A Decade of Aerosol Optical Properties Measurements over Athens, Greece. Atmosphere. 2020; 11 (2):154.
Chicago/Turabian StyleIoannis-Panagiotis Raptis; Stelios Kazadzis; Vassilis Amiridis; Antonis Gkikas; Evangelos Gerasopoulos; Nikolaos Mihalopoulos. 2020. "A Decade of Aerosol Optical Properties Measurements over Athens, Greece." Atmosphere 11, no. 2: 154.
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 global climatology of absorbing carbonaceous aerosols (ACA) for the period 2005–2015 is obtained by using satellite MODIS (Moderate Resolution Imaging Spectroradiometer)-Aqua and OMI (Ozone Monitoring Instrument)-Aura aerosol optical properties and by applying an algorithm. The algorithm determines the frequency of presence of ACA (black and brown carbon) over the globe at 1° × 1° pixel level and on a daily basis. The results of the algorithm indicate high frequencies of ACA (up to 19 days/month) over world regions with extended biomass burning, such as the tropical forests of southern and central Africa, South America and equatorial Asia, over savannas, cropland areas or boreal forests, as well as over urban and rural areas with intense anthropogenic activities, such as the eastern coast of China or the Indo-Gangetic plain. A clear seasonality of the frequency of occurrence of ACA is evident, with increased values during June–October over southern Africa, during July–November over South America, August–November over Indonesia, November–March over central Africa and November–April over southeastern Asia. The estimated seasonality of ACA is in line with the known annual patterns of worldwide biomass-burning emissions, while other features such as the export of carbonaceous aerosols from southern Africa to the southeastern Atlantic Ocean are also successfully reproduced by the algorithm. The results indicate a noticeable interannual variability and tendencies of ACA over specific world regions during 2005–2015, such as statistically significant increasing frequency of occurrence over southern Africa and eastern Asia.
Nikolaos Hatzianastassiou; Nikoleta Kalaitzi; Maria Gavrouzou; Antonis Gkikas; Marios-Bruno Korras-Carraca; Nikolaos Mihalopoulos. A Climatological Satellite Assessment of Absorbing Carbonaceous Aerosols on a Global Scale. Atmosphere 2019, 10, 671 .
AMA StyleNikolaos Hatzianastassiou, Nikoleta Kalaitzi, Maria Gavrouzou, Antonis Gkikas, Marios-Bruno Korras-Carraca, Nikolaos Mihalopoulos. A Climatological Satellite Assessment of Absorbing Carbonaceous Aerosols on a Global Scale. Atmosphere. 2019; 10 (11):671.
Chicago/Turabian StyleNikolaos Hatzianastassiou; Nikoleta Kalaitzi; Maria Gavrouzou; Antonis Gkikas; Marios-Bruno Korras-Carraca; Nikolaos Mihalopoulos. 2019. "A Climatological Satellite Assessment of Absorbing Carbonaceous Aerosols on a Global Scale." Atmosphere 10, no. 11: 671.