Seasonal variability of optical properties of aerosols in the Eastern Mediterranean

Vrekoussis, Mihalis; Liakakou, Eleni; Koçak, Mustafa; Kubilay, N.; Oikonomou, K.; Sciare, Jean; Mihalopoulos, N.

doi:10.1016/j.atmosenv.2005.08.011

Cited by 98 publications

(60 citation statements)

References 36 publications

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“…In addition, the mean value of σ sp (61±31 Mm −1 at 550 nm) observed at Granada is similar to the σ sp (525 nm)=60 Mm −1 obtained at this urban costal site during (Saha et al, 2008 and is almost comparable to those obtained in northern Greece (65±31 Mm −1 ) and Sede Boker, Israel (60±31 Mm −1 ) by Gerasopoulos et al (2003) and Derimian et al (2006), respectively. However, our σ sp average value is relatively larger than the average values measured by Pereira et al (2008), at Evora, Portugal (46 Mm −1 ), and by Vrekoussis et al (2005), in remote areas of Greece and Turkey (50 and 45 Mm −1 ). Nevertheless, the measured σ sp values at Granada are lower than those obtained in highly polluted areas in US (Greenwald et al, 2007;Carrico et al, 2003) and are much smaller than those observed in large urban areas in Asia (Bergin et al, 2001;Andreae et al, 2008;Garland et al, 2008;Ganguly et al, 2006).…”

Section: Aerosol Scattering Absorption Coefficients and Aerosol Numbecontrasting

confidence: 39%

Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

2010

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Abstract. Measurements of aerosol optical properties and aerosol number size distribution obtained during the period from December 2005 to November 2007 at Granada, an urban site in south-eastern Spain, are analyzed. Large variations of the measured variables have been found, and related to variations in emissions sources and meteorological conditions. High values of aerosol absorption and scattering coefficients are obtained during winter and low values are measured during summer. This seasonal pattern in the surface aerosol optical properties is opposite to the seasonal cycle showed by columnar aerosol optical depth. The differences in the seasonal features of the surface and column-integrated data are related to seasonal variations in the aerosol vertical distribution, aerosol sources and boundary layer height. In winter the number density of "fine" particles (0.5

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Section: Aerosol Scattering Absorption Coefficients and Aerosol Numbecontrasting

confidence: 39%

Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

2010

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“…A good correlation was observed also for fine sulfate particles with R 2 higher than 0.82 after excluding specific days highlighted by the orange boxed areas. In these specific days the high measured scattering coefficients were likely due to high concentrations of coarse crustal particles (<C> PM 10 = 8.5±12.7 µg m −3 ) which favoured the 4 > PM 10 = 2.0±0.9 µg m −3 ), thus increasing the scattering (Vrekoussis et al, 2005;Adams et al, 2005). In fact, the mean <C> PM 10 and <SO 2− 4 > PM 10 calculated over the points included in the fitting process were 1.7±1.2 µg m −3 and 0.7±0.5 µg m −3 , respectively.…”

Section: −mentioning

confidence: 99%

“…As shown in this work, the in-situ measurements are helpful in order to describe the effects of mesoscale weather systems such as the breeze circulation on aerosol optical properties. A number of studies have been published on in-situ aerosol optical measurements in the Eastern Mediterranean (Vrekoussis et al, 2005;Ichoku et al, 1999;Formenti et al, 2001;Sciare et al, 2005;Kouvarakis et al, 2002;Andreae et al, 2002;Gerasopoulos et al, 2003;Sabbah et al, 2001;Israelevich et al, 2002), Central Mediterranean and South Italy (Pace et al, 2006;Esposito et al, 2004), South Iberian Peninsula (Pereira et al, 2011;Lyamani et al, 2008). However, little has been published on aerosol optical properties in the Western Mediterranean Basin (Mallet et al, 2003;Saha et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Variability of aerosol optical properties in the Western Mediterranean Basin

et al. 2011

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Abstract. Aerosol light scattering, absorption and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Mean scattering and hemispheric backscattering coefficients (@ 635 nm) were 26.6±23.2 Mm −1 and 4.3±2.7 Mm −1 , respectively and the mean aerosol absorption coefficient (@ 637 nm) was 2.8±2.2 Mm −1 . Mean values of Single Scattering Albedo (SSA) andÅngström exponent (å) (calculated from 450 nm to 635 nm) at MSY were 0.90±0.05 and 1.3±0.5 respectively. A clear relationship was observed between the PM 1 /PM 10 and PM 2.5 /PM 10 ratios as a function of the calculatedÅngström exponents. Mass scattering cross sections (MSC) for fine mass and sulfate at 635 nm were 2.8±0.5 m 2 g −1 and 11.8±2.2 m 2 g −1 , respectively, while the mean aerosol absorption cross section (MAC) was 10.4±2.0 m 2 g −1 . The variability in aerosol optical properties in the WMB were largely explained by the origin and ageing of air masses over the measurement site. The MAC values appear dependent of particles aging: similar to the expected absorption cross-section for fresh emissions under Atlantic Advection episodes and higher under aerosol pollution episodes. The analysis of theÅngström exponent as a function of the origin the air masses revealed that polluted winter anticyclonic conditions and summer recirculation scenarios typical of the WMB led to an increase of fine particles in the atmosphere (å = 1.5±0.1) while the aerosol optical properties under Atlantic Advection episodes and Saharan dust outbreaks were clearly dominated by coarser particles (å = 1.0±0.4). The sea breeze played an important role Correspondence to: M. Pandolfi (marco.pandolfi@idaea.csic.es) in transporting pollutants from the developed WMB coastlines towards inland rural areas, changing the optical properties of aerosols. Aerosol scattering and backscattering coefficients increased by around 40 % in the afternoon when the sea breeze was fully developed while the absorption coefficient increased by more than 100 % as a consequence of the increase in the equivalent black carbon concentration (EBC) observed at MSY under sea breeze circulation.

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“…Brown et al (2004) have suggested that the conversion efficiency of NO x to HNO 3 during nighttime can be equivalent to the daytime photochemical conversion. Moreover, Vrekoussis et al (2006) have found that ~55-65% of the total production of nighttime HNO 3 and NO 3 − were through the heterogeneous reactions of NO 3 radical in an anthropogenically-influenced eastern Mediterranean marine boundary layer. The higher abundances of NO x and high RH may facilitate the secondary NO 3 NO 3 − formation during the wintertime in the polluted atmosphere of the IGP (Ram and Sarin, 2011).…”

Section: Sulphur and Nitrogen Oxidation Ratios (Sor And Nor)mentioning

confidence: 99%

Carbonaceous and Secondary Inorganic Aerosols during Wintertime Fog and Haze over Urban Sites in the Indo-Gangetic Plain

Ram

Sarin

Sudheer

et al. 2012

Aerosol Air Qual. Res.

132

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The chemical composition of total suspended particulate (TSP) matter and secondary aerosol formation have been studied during wintertime fog and haze events from urban sites (Allahabad and Hisar) in the Indo-Gangetic Plain. The atmospheric abundances of elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC) suggest that organic matter is a major component of TSP, followed by concentrations of sulphate and nitrate under varying meteorological conditions. The concentrations of EC, OC, and WSOC show a nearly 30% increase during fog and haze events at Allahabad and a marginal increase at Hisar; whereas inorganic constituents (NH 4 + , NO 3 − and SO 4 2− ) are 2-3 times higher than those during clear days at both the locations. The sulphur and nitrogen oxidation ratios (SOR and NOR) also exhibit significant increases suggesting possible enhancement of secondary formation of SO 4 2− and NO 3 − during fog and haze events. The significant correlation between NH 4 + -SO 4 2− (R 2 = 0.66, n = 61) and an NH 4 + /SO 4 2− equivalent ratio ≥ 1 during fog-haze conditions suggest nearcomplete neutralization of sulphuric acid by ammonia. In contrast, NH 4 + /SO 4 2− equivalent ratios are less than 1 during normal days suggesting an NH 3 -deficient environment and the possible association of SO 4 2− with mineral dust for neutralization. Secondary inorganic aerosol formation and their hygroscopic growth can have significant impact on atmospheric chemistry, air-quality and visibility impairment during fog-haze events over northern India.

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Seasonal variability of optical properties of aerosols in the Eastern Mediterranean

Cited by 98 publications

References 36 publications

Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

Variability of aerosol optical properties in the Western Mediterranean Basin

Carbonaceous and Secondary Inorganic Aerosols during Wintertime Fog and Haze over Urban Sites in the Indo-Gangetic Plain

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