Large aerosol effects on ozone photolysis in the Mediterranean

Casasanta, Giampietro; Sarra, Alcide di; Meloni, Daniela; Monteleone, Francesco; Pace, Giandomenico; Piacentino, Salvatore; Sferlazzo, Damiano

doi:10.1016/j.atmosenv.2011.04.065

Cited by 39 publications

(58 citation statements)

References 44 publications

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“…In its turn, the OH production is linked to elevated levels of ultraviolet radiation. The central Mediterranean is characterized by elevated levels of UV radiation in summer, and high ozone photolysis and OH production (e.g., Casasanta et al, 2011). Consequently, SO 2 conversion into SO 2− 4 is expected to be faster in summer.…”

Section: Seasonal Evolutionmentioning

confidence: 99%

Evidence for heavy fuel oil combustion aerosols from chemical analyses at the island of Lampedusa: a possible large role of ships emissions in the Mediterranean

et al. 2012

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Abstract. Measurements of aerosol chemical composition made on the island of Lampedusa, south of the Sicily channel, during years [2004][2005][2006][2007][2008], are used to identify the influence of heavy fuel oil (HFO) combustion emissions on aerosol particles in the Central Mediterranean. Aerosol samples influenced by HFO are characterized by elevated Ni and V soluble fraction (about 80 % for aerosol from HFO combustion, versus about 40 % for crustal particles), high V and Ni to Si ratios, and values of V sol > 6 ng m −3 . Evidence of HFO combustion influence is found in 17 % of the daily samples. Back trajectories analysis on the selected events show that air masses prevalently come from the Sicily channel region, where an intense ship traffic occurs. This behavior suggests that single fixed sources like refineries are not the main responsible for the elevated V and Ni events, which are probably mainly due to ships emissions.V sol , Ni sol , and non-sea salt SO 2− 4 (nssSO 2− 4 ) show a marked seasonal behaviour, with an evident summer maximum. Such a pattern can be explained by several processes: (i) increased photochemical activity in summer, leading to a faster production of secondary aerosols, mainly nssSO 2− 4 , from the oxidation of SO 2 (ii) stronger marine boundary layer (MBL) stability in summer, leading to higher concentration of emitted compounds in the lowest atmospheric layers. A very intense event in spring 2008 was studied in detail, also using size segregated chemical measurements. These data show that elements arising from heavy oil combustion (V, Ni, Al, Fe) are distributed in the sub-micrometric fraction of the aerosol, and the metals are present as free metals, carbonates, oxides hydrates or labile complex with organic ligands, so that they are dissolved in mild condition (HNO 3 , pH1.5).Data suggest a characteristic nssSO 2− 4 /V ratio in the range 200-400 for HFO combustion aerosols in summer at Lampedusa. By using the value of 200 a lower limit for the HFO contribution to total sulphates is estimated. HFO combustion emissions account, as a summer average, at least for 1.2 µg m −3 , representing about 30 % of the total nssSO 2− 4 , 3.9 % of PM 10 , 8 % of PM 2.5 , and 11 % of PM1. Within the used dataset, sulphate from HFO combustion emissions reached the peak value of 6.1 µg m −3 on 26 June 2008, when it contributed by 47 % to nssSO 2− 4 , and by 15 % to PM 10 .

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Section: Seasonal Evolutionmentioning

confidence: 99%

Evidence for heavy fuel oil combustion aerosols from chemical analyses at the island of Lampedusa: a possible large role of ships emissions in the Mediterranean

et al. 2012

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“…Local studies previously mentioned Saha et al, 2008;Pace et al, 2005;Péré et al, 2011;Meloni et al, 2015) clearly report significant SW heating rate due to absorbing particles with values reaching up to 2-3 K per day, depending on the aerosol types. Finally, aerosols also have a significant effect on photolysis rates that may affect tropospheric chemistry and ozone production over the basin (Casasanta et al, 2011;Mailler et al, 2015).…”

Section: Mallet Et Al: Overview Of the Charmex/adrimed Summer 201mentioning

confidence: 99%

Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

et al. 2016

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Abstract. The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental setup also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote-sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modeling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to producing high levels of atmospheric pollutants or intense biomass burning events in the region. However, numerous mineral dust plumes were observed during the campaign, with the main sources located in Morocco, Algeria and Tunisia, leading to aerosol optical depth (AOD) values ranging between 0.2 and 0.6 (at 440 nm) over the western and central Mediterranean basins. One important point of this experiment concerns the direct observations of aerosol extinction onboard the ATR-42, using the CAPS system, showing local maxima reaching up to 150 M m −1 within the dust plume. Non-negligible aerosol extinction (about 50 M m −1 ) has also been observed within the marine boundary layer (MBL). By combining the ATR-42 extinction coefficient observations with absorption and scattering measurements, we performed a complete optical closure revealing excellent agreement with estimated optical properties. This additional information on extinction properties has allowed calculation of the dust single scattering albedo (SSA) with a high level of confidence over the western Mediterranean. Our results show a moderate variability from 0....

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“…The Å ngstro¨m exponent was calculated from the AOD at 415 and 869 nm and provides an indication of the columnar aerosol size distribution; high and low values of a indicate, respectively, the dominant effect of fine and coarse particles. The ozone photolysis frequency, J(O 1 D), is estimated from DAS observations (Casasanta et al, 2011) and provides an indication of the atmospheric photochemical activity. LIDAR measurements were routinely made with one 15-minute interval of continuous measurements per hour throughout the campaign, providing the temporal evolution of the aerosol vertical distribution.…”

Section: The More Campaignmentioning

confidence: 99%

On the complexity of the boundary layer structure and aerosol vertical distribution in the coastal Mediterranean regions: a case study

Pace¹,

Junkermann

Vitali³

et al. 2015

Tellus B: Chemical and Physical Meteorology

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A B S T R A C TThe planetary boundary layer structure in the coastal areas, and particularly in complex orography regions such as the Mediterranean, is extremely intricate. In this study, we show the evolution of the planetary boundary layer based on in situ airborne measurements and ground-based remote sensing observations carried out during the MORE (Marine Ozone and Radiation Experiment) campaign in June 2010. The campaign was held in a rural coastal Mediterranean region in Southern Italy. The study focuses on the observations made on 17 June. Vertical profiles of meteorological parameters and aerosol size distribution were measured during two flights: in the morning and in the afternoon. Airborne observations were combined with ground-based LIDAR, SODAR, microwave and visible radiometer measurements, allowing a detailed description of the atmospheric vertical structure. The analysis was complemented with data from a regional atmospheric model run with horizontal resolutions of 12, 4 and 1 km, respectively; back-trajectories were calculated at these spatial resolutions. The observations show the simultaneous occurrence of dust transport, descent of mid-tropospheric air and sea breeze circulation on 17 June. Local pollution effects on the aerosol distribution, and a possible event of new particles formation were also observed. A large variability in the thermodynamical structure and aerosol distribution in the flight region, extending by approximately 30 km along the coast, was found. Within this complex, environment-relevant differences in the back-trajectories calculated at different spatial resolutions are found, suggesting that the description of several dynamical processes, and in particular the sea breeze circulation, requires high-resolution meteorological analyses. The study also shows that the integration of different observational techniques is needed to describe these complex conditions; in particular, the availability of flights and their timing with respect to the occurring phenomena are crucial.

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Large aerosol effects on ozone photolysis in the Mediterranean

Cited by 39 publications

References 44 publications

Evidence for heavy fuel oil combustion aerosols from chemical analyses at the island of Lampedusa: a possible large role of ships emissions in the Mediterranean

Evidence for heavy fuel oil combustion aerosols from chemical analyses at the island of Lampedusa: a possible large role of ships emissions in the Mediterranean

Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

On the complexity of the boundary layer structure and aerosol vertical distribution in the coastal Mediterranean regions: a case study

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