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Makkhan SJS, Singh S, Parmar KS, Kaushal S, Soni K. Comparison of hybrid machine learning model for the analysis of black carbon in air around the major coal mines of India. Neural Comput Appl 2022. [DOI: 10.1007/s00521-022-07909-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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2
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Global Spatial and Temporal Variation of the Combined Effect of Aerosol and Water Vapour on Solar Radiation. REMOTE SENSING 2021. [DOI: 10.3390/rs13040708] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study aims to calculate the combined and individual effects of the optical thickness of aerosols (AOT) and precipitable water vapour (PWV) on the solar radiation reaching the Earth’s surface at a global scale and to analyse its spatial and temporal variation. For that purpose, a novel but validated methodology is applied to CERES SYN1deg products for the period 2000–2019. Spatial distributions of AOT and PWV effects, both individually and combined, show a close link with the spatial distributions of AOT and PWV. The spatially averaged combined effect results in a −13.9% reduction in irradiance, while the average AOT effect is −2.3%, and the PWV effect is −12.1%. The temporal analysis focuses on detecting trends in the anomalies. The results show overall positive trends for AOT and PWV. Consequently, significant negative overall trends are found for the effects. However, significant positive trends for the individual AOT and the combined AOT-PWV effects are found in specific regions, such as the eastern United States, Europe or Asia, indicating successful emission control policies in these areas. This study contributes to a better understanding of the individual and combined effects of aerosols and water vapour on solar radiation at a global scale.
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Atmospheric Aerosol Distribution in 2016–2017 over the Eastern European Region Based on the GEOS-Chem Model. ATMOSPHERE 2020. [DOI: 10.3390/atmos11070722] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The spatial and temporal distributions of atmospheric aerosols have been simulated using the GEOS-Chem model over the sparsely investigated Eastern European region. The spatial distribution of the particulate matter (PM2.5) concentration, mineral dust, black carbon, organic aerosols, sea salt, as well as nitrate, sulfate, and ammonium aerosols during 2016–2017 were considered. The aerosols’ concentration, seasonality and spatial features were determined for the region. Particulate matter (PM2.5) contamination prevails in Poland in late autumn and winter. The monthly mean PM2.5 concentration reached 55 µg m−3 over the Moscow region in the early spring of both years. The mineral dust concentration varied significantly, reaching 40 µg m−3 over the southwestern part of Eastern Europe in March 2016. The areas most polluted by black carbon aerosols were the central and southern parts of Poland in the winter. The organic aerosols’ concentration was the largest in March and April, reaching 10 µg m−3 over East Belarus. The sea salt aerosol concentration increased in the coastal regions in winter due to the wind strength. Mineral dust aerosols in Eastern Europe are mainly composed of dust, partially transported from the Ukrainian steppe and partially from the Saharan Desert.
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Clear-Sky Surface Solar Radiation and the Radiative Effect of Aerosol and Water Vapor Based on Simulations and Satellite Observations over Northern China. REMOTE SENSING 2020. [DOI: 10.3390/rs12121931] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The distribution and trend of clear-sky surface solar radiation (SSR) and the quantitative effects of aerosol and water vapor are investigated in northern China during 2001–2015 using radiation simulations and satellite observations. Clear-sky SSR in northern China is high in summer and low in winter, which is dominated by astronomical factors and strongly modulated by the seasonal variations of radiative effects of aerosol (ARE) and water vapor (WVRE). The larger variation of WVRE than ARE indicates that water vapor plays a more important role in moderating the seasonal variation of clear-sky SSR. Clear-sky SSR shows an overall decreasing trend of –0.12 W/m2 per year, with decrease more strongly than –0.60 W/m2 per year in west-central Shandong and increase (about 0.40 W/m2) in south-central Inner Mongolia. The consistency of spatial distribution and high correlation between clear-sky SSR and ARE trend indicate that the clear-sky SSR trend is mainly determined by aerosol variation. Dust mass concentration decreases about 16% in south-central Inner Mongolia from 2001 to 2015, resulting in the increase in clear-sky SSR. In contrast, sulfate aerosol increases about 92% in west-central Shandong, leading to the decreasing trend of clear-sky SSR.
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Multifractal Detrended Cross-Correlation Analysis of Global Methane and Temperature. REMOTE SENSING 2020. [DOI: 10.3390/rs12030557] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Multifractal Detrended Cross-Correlation Analysis (MF-DCCA) was applied to time series of global methane concentrations and remotely-sensed temperature anomalies of the global lower and mid-troposphere, with the purpose of investigating the multifractal characteristics of their cross-correlated time series and examining their interaction in terms of nonlinear analysis. The findings revealed the multifractal nature of the cross-correlated time series and the existence of positive persistence. It was also found that the cross-correlation in the lower troposphere displayed more abundant multifractal characteristics when compared to the mid-troposphere. The source of multifractality in both cases was found to be mainly the dependence of long-range correlations on different fluctuation magnitudes. Multifractal Detrended Fluctuation Analysis (MF-DFA) was also applied to the time series of global methane and global lower and mid-tropospheric temperature anomalies to separately study their multifractal properties. From the results, it was found that the cross-correlated time series exhibit similar multifractal characteristics to the component time series. This could be another sign of the dynamic interaction between the two climate variables.
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Tzanis CG, Alimissis A, Philippopoulos K, Deligiorgi D. Applying linear and nonlinear models for the estimation of particulate matter variability. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 246:89-98. [PMID: 30529945 DOI: 10.1016/j.envpol.2018.11.080] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/16/2018] [Accepted: 11/24/2018] [Indexed: 05/16/2023]
Abstract
In this study, data collected from an urban air quality monitoring network are being used for the purpose of evaluating various methodologies used for spatial interpolation in the context of proposing an effective yet simple to apply scheme for PM spatial point estimations. The examined methods are the Inverse Distance Weighting, two linear regression models, the Multiple Linear Regression and the Linear Mixed Model, along with a Feed Forward Neural Network (FFNN) model. These schemes utilize daily PM10 and PM2.5 concentrations collected from five and three air quality monitoring sites respectively. In order to obtain the resulted estimations, the leave-one-out cross-validation methodology is used for all methods. The evaluation of their predictive ability is performed by using a combination of difference and correlation statistical measures, scatter plots and statistical tests. The results indicate the usefulness of FFNNs as they are found to be statistically significantly superior for modelling the particulate matter spatial variability. The model performance statistics show that in most cases the error values are considerably lower for the FFNN model. Additionally, the rank and Wilcoxon rank tests reveal that the null hypothesis for equal predictive accuracy is rejected for the majority of monitoring sites and schemes (values lower than the critical t-value). According to the comparison results, the FFNN model is selected for forecasting air quality limit exceedances set by the European Union and World Health Organization air quality standards. For two monitoring sites in which the largest number of exceedances occurred, the probability of detection is high while the probability of false detection is very low, further establishing the neural networks' predictive ability.
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Affiliation(s)
- Chris G Tzanis
- Section of Environmental Physics and Meteorology, Department of Physics, National and Kapodistrian University of Athens, 15784 Athens, Greece.
| | - Anastasios Alimissis
- Section of Environmental Physics and Meteorology, Department of Physics, National and Kapodistrian University of Athens, 15784 Athens, Greece
| | - Kostas Philippopoulos
- Section of Environmental Physics and Meteorology, Department of Physics, National and Kapodistrian University of Athens, 15784 Athens, Greece
| | - Despina Deligiorgi
- Section of Environmental Physics and Meteorology, Department of Physics, National and Kapodistrian University of Athens, 15784 Athens, Greece
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The Spatial and Temporal Distributions of Absorbing Aerosols over East Asia. REMOTE SENSING 2017. [DOI: 10.3390/rs9101050] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Varotsos CA, Mazei YA, Burkovsky I, Efstathiou MN, Tzanis CG. Climate scaling behaviour in the dynamics of the marine interstitial ciliate community. THEORETICAL AND APPLIED CLIMATOLOGY 2016; 125:439-447. [DOI: 10.1007/s00704-015-1520-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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Krapivin VF, Varotsos CA, Christodoulakis J. Mission to Mars: Adaptive Identifier for the Solution of Inverse Optical Metrology Tasks. EARTH, MOON, AND PLANETS 2016; 118:1-14. [DOI: 10.1007/s11038-016-9487-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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Varotsos CA, Tzanis C, Cracknell AP. Precursory signals of the major El Niño Southern Oscillation events. THEORETICAL AND APPLIED CLIMATOLOGY 2016; 124:903-912. [DOI: 10.1007/s00704-015-1464-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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Varotsos C, Tzanis C, Efstathiou M, Deligiorgi D. Tempting long-memory in the historic surface ozone concentrations at Athens, Greece. ATMOSPHERIC POLLUTION RESEARCH 2015; 6:1055-1057. [DOI: 10.1016/j.apr.2015.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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Modelling climate change impacts on the seasonality of water resources in the Upper Ca River Watershed in Southeast Asia. ScientificWorldJournal 2014; 2014:279135. [PMID: 25243206 PMCID: PMC4150503 DOI: 10.1155/2014/279135] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 07/03/2014] [Indexed: 12/04/2022] Open
Abstract
The impact of climate change on the seasonality of water resources in the Upper Ca River Watershed in mainland Southeast Asia was assessed using downscaled global climate models coupled with the SWAT model. The results indicated that temperature and evapotranspiration will increase in all months of future years. The area could warm as much as 3.4°C in the 2090s, with an increase of annual evapotranspiration of up to 23% in the same period. We found an increase in the seasonality of precipitation (both an increase in the wet season and a decrease in the dry season). The greatest monthly increase of up to 29% and the greatest monthly decrease of up to 30% are expected in the 2090s. As a result, decreases in dry season discharge and increases in wet season discharge are expected, with a span of ±25% for the highest monthly changes in the 2090s. This is expected to exacerbate the problem of seasonally uneven distribution of water resources: a large volume of water in the wet season and a scarcity of water in the dry season, a pattern that indicates the possibility of more frequent floods in the wet season and droughts in the dry season.
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Varotsos CA, Efstathiou MN, Cracknell AP. On the scaling effect in global surface air temperature anomalies. ATMOSPHERIC CHEMISTRY AND PHYSICS 2013; 13:5243-5253. [DOI: 10.5194/acp-13-5243-2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Abstract. The annual and the monthly mean values of the land-surface air temperature anomalies from 1880–2011, over both hemispheres, are used to investigate the existence of long-range correlations in their temporal evolution. The analytical tool employed is the detrended fluctuation analysis, which eliminates the noise of the non-stationarities that characterize the land-surface air temperature anomalies in both hemispheres. The reliability of the results obtained from this tool (e.g., power-law scaling) is investigated, especially for large scales, by using error bounds statistics, the autocorrelation function (e.g., rejection of its exponential decay) and the method of local slopes (e.g., their constancy in a sufficient range). The main finding is that deviations of one sign of the land-surface air temperature anomalies in both hemispheres are generally followed by deviations with the same sign at different time intervals. In other words, the land-surface air temperature anomalies exhibit persistent behaviour, i.e., deviations tend to keep the same sign. Taking into account our earlier study, according to which the land and sea surface temperature anomalies exhibit scaling behaviour in the Northern and Southern Hemisphere, we conclude that the difference between the scaling exponents mainly stems from the sea surface temperature, which exhibits a stronger memory in the Southern than in the Northern Hemisphere. Moreover, the variability of the scaling exponents of the annual mean values of the land-surface air temperature anomalies versus latitude shows an increasing trend from the low latitudes to polar regions, starting from the classical random walk (white noise) over the tropics. There is a gradual increase of the scaling exponent from low to high latitudes (which is stronger over the Southern Hemisphere).
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Kavouras IG, Lianou M, Chalbot MC, Vei IC, Kotronarou A, Hoek G, Hameri K, Harrison RM. Quantitative determination of regional contributions to fine and coarse particle mass in urban receptor sites. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2013; 176:1-9. [PMID: 23395988 DOI: 10.1016/j.envpol.2013.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 12/31/2012] [Accepted: 01/04/2013] [Indexed: 06/01/2023]
Abstract
In this study, we demonstrate that regression analysis of trajectories residence time estimates the contributions of geographical sectors to fine and coarse particle mass in urban receptor sites. We applied the methodology to coarse and fine particles in Amsterdam, Athens, Birmingham and Helsinki. The sectors with the highest contributions on PM2.5 and PM10-2.5 for Amsterdam and Birmingham were Central/Eastern Europe and the Atlantic Ocean/North Sea, respectively. For Athens, the four sectors within 500 km accounted for the largest fraction of PM2.5. The Mediterranean Sea and North Africa added more than half of PM10-2.5 in Athens. For Helsinki, more than 50% of PM2.5 and PM10-2.5 were from sources outside Finland. This approach may be applied to assess the impact of transport on particle mass levels, identify the spatial patterns of particle sources and generate valuable data to design national and transnational efficient emission control strategies.
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Affiliation(s)
- I G Kavouras
- Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Athens, GR 15236, Greece.
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Efstathiou MN, Varotsos CA. On the 11 year solar cycle signature in global total ozone dynamics. METEOROLOGICAL APPLICATIONS 2013; 20:72-79. [DOI: 10.1002/met.1287] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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Varotsos C, Ondov J, Tzanis C, Öztürk F, Nelson M, Ke H, Christodoulakis J. An observational study of the atmospheric ultra-fine particle dynamics. ATMOSPHERIC ENVIRONMENT 2012; 59:312-319. [DOI: 10.1016/j.atmosenv.2012.05.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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17
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Tzanis C, Varotsos C, Christodoulakis J, Tidblad J, Ferm M, Ionescu A, Lefevre RA, Theodorakopoulou K, Kreislova K. On the corrosion and soiling effects on materials by air pollution in Athens, Greece. ATMOSPHERIC CHEMISTRY AND PHYSICS 2011; 11:12039-12048. [DOI: 10.5194/acp-11-12039-2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Abstract. In the frame of the European project, entitled MULTI-ASSESS, specimens of structural metals, glass, stone and concrete materials were exposed to air pollution at a station, which was installed for this purpose on a building, located in the centre of Athens. The main purpose of this project was to determine the corrosion and soiling effects of air pollution on materials. A set of the specimens was exposed in a position that was sheltered from rain and partly from wind, and another set was exposed in unsheltered positions on the roof of the above said building. In addition, other specimens were exposed at different heights on the same building, in order to investigate for the first time the corrosion and soiling effects on various materials as a function of height. For the determination of these effects, chemical analysis of the specimens was performed and basic parameters as the weight change, the layer thickness and the optical properties were calculated. Finally, the results obtained are discussed and their plausible interpretation is attempted.
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Efstathiou MN, Tzanis C, Cracknell AP, Varotsos CA. New features of land and sea surface temperature anomalies. INTERNATIONAL JOURNAL OF REMOTE SENSING 2011; 32:3231-3238. [DOI: 10.1080/01431161.2010.541504] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Affiliation(s)
- M. N. Efstathiou
- a Department of Applied Physics , University of Athens, University Campus Bldg. Phys. V , Athens, 15784, Greece
| | - C. Tzanis
- a Department of Applied Physics , University of Athens, University Campus Bldg. Phys. V , Athens, 15784, Greece
| | - A. P. Cracknell
- b Division of Electronic Engineering and Physics , University of Dundee, Dundee DD1 4HN , Scotland, UK
| | - C. A. Varotsos
- a Department of Applied Physics , University of Athens, University Campus Bldg. Phys. V , Athens, 15784, Greece
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Varotsos CA, Zellner R. A new modeling tool for the diffusion of gases in ice or amorphous binary mixture in the polar stratosphere and the upper troposphere. ATMOSPHERIC CHEMISTRY AND PHYSICS 2010; 10:3099-3105. [DOI: 10.5194/acp-10-3099-2010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Abstract. To elaborate stratospheric ozone depletion processes, measurements of diffusion coefficients of selected gas phase molecules (i.e. HCl, CH3OH, HCOOH and CH3COOH; Katsambas et al., 1997; Kondratyev and Varotsos, 1996; Varotsos et al., 1994, 1995) in ice in the temperature range 170–195 K have been analyzed with respect to the mechanisms and rates of diffusion. It is argued that the diffusion in ice of these compounds is governed by a vacancy – mediated mechanism, i.e. H2O vacancies are required to diffuse to lattice sites adjacent to these compounds prior to the diffusion of the corresponding molecule into the vacancy sites. In addition, we show that the diffusion coefficients of these compounds exhibit a specific interconnection, i.e. a linear relationship holds between the logarithm of the pre-exponential factor, Do, and the activation energy E. The physical meaning of this interconnection is discussed.
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Efstathiou MN, Varotsos CA. On the altitude dependence of the temperature scaling behaviour at the global troposphere. INTERNATIONAL JOURNAL OF REMOTE SENSING 2010; 31:343-349. [DOI: 10.1080/01431160902882702] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Affiliation(s)
- M. N. Efstathiou
- a Department of Applied Physics , University of Athens , Panepistimioupolis, PHYS-V, ATH, 157 84, Greece
| | - C. A. Varotsos
- a Department of Applied Physics , University of Athens , Panepistimioupolis, PHYS-V, ATH, 157 84, Greece
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Tzanis C, Varotsos C, Ferm M, Christodoulakis J, Assimakopoulos MN, Efthymiou C. Nitric acid and particulate matter measurements at Athens, Greece, in connection with corrosion studies. ATMOSPHERIC CHEMISTRY AND PHYSICS 2009; 9:8309-8316. [DOI: 10.5194/acp-9-8309-2009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Abstract. For a long time, scientists have been concerned about the effects of air pollution on materials and especially on the monuments of the cultural heritage. The EU funded a project, entitled MULTI-ASSESS, to determine these effects and to develop dose-response functions appropriate for the new multi-pollutant environment. The University of Athens participated in this effort as a targeted field exposure test site. In the present paper, the measurements of the passive samplers, which were exposed during the same period with the samples for corrosion studies, at the Athens station, are presented. The results have shown that only 16.5% of the deposited mass was water soluble. The vertical distribution of passive particle collectors has led to the conclusion that the height of maximum deposition of each ion is different. In addition, a variation of the water-soluble mass to total deposited mass between 8% and 31% was observed.
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