Short-Term Variability of Atmospheric DMS and Its Oxidation Products at Amsterdam Island during Summer Time

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Interannual variability of methanesulfonate in rainwater at Amsterdam Island (Southern Indian Ocean)

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Seasonal Variation of Dimethylsulfoxide in Rainwater at Amsterdam Island in the Southern Indian Ocean: Implications on the Biogenic Sulfur Cycle

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Spatial and temporal variability of atmospheric sulfur-containing gases and particles during the Albatross campaign

International audienceTo investigate the oxidation chemistry of dimethylsulfide (DMS) in the marine atmosphere, atmospheric DMS, SO2, as well as several DMS oxidation products in aerosol phase such as non-sea-salt sulfate (nss-SO4), methanesulfonate (MSA), and dimethylsulfoxide (DMSOp) have been measured during the Albatross campaign in the Atlantic Ocean from October 9 to November 2, 1996. Long-range transport, local sea-to-air flux of DMS (Frms), marine boundary layer (MBL) height variation, and photochemistry were found to be the major factors controlling atmospheric DMS concentration which ranged from 29 to 396 parts per trillion by volume (pptv) (mean of 120+_68 pptv) over the cruise. The spatial variability of MSA and DMSOp follows the latitudinal variations of FvMs. A 2-day period of intensive photochemistry associated with quite stable atmospheric conditions south of the equator allowed the observation of anticorrelated diurnal variations between DMS and its main oxidation products. A chemical box model describing sulfur chemistry in the marine atmosphere was used to reproduce these variations and investigate coherence of experimentally calculated fluxes FvMs with observed DMS atmospheric concentrations. The model results reveal that the measured OH levels are not sufficient to explain the observed DMS daytime variation. Oxidizing species other than OH, probably BrO, must be involved in the oxidation of DMS to reproduce the observed data

Role of the NO₃ radicals in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign

During the MINOS campaign (28 July-18 August 2001) the nitrate (NO₃) radical was measured at Finokalia station, on the north coast of Crete in South-East Europe using a long path (10.4 km) Differential Optical Absorption Spectroscopy instrument (DOAS). Hydroxyl (OH) radical was also measured by a Chemical Ionization Mass-Spectrometer (Berresheim et al., 2003). These datasets represent the first simultaneous measurements of OH and NO₃ radicals in the area. NO₃ radical concentrations ranged from less than 3x10⁷ up to 9x10⁸ radicals· cm^-3 with an average nighttime value of 1.1x10⁸ radicals· cm^-3.<br> <br> The observed NO₃ mixing ratios are analyzed on the basis of the corresponding meteorological data and the volatile organic compound (VOC) observations which were measured simultaneously at Finokalia station. The importance of the NO₃ radical chemistry relatively to that of OH in the dimethylsulfide (DMS) and nitrate cycles is also investigated. The observed NO₃ levels regulate the nighttime variation of DMS. The loss of DMS by NO₃ during night is about 75% of that by OH radical during day. NO₃ and nitrogen pentoxide (N₂O₅) reactions account for about 21% of the total nitrate (HNO_3(g)+NO^-_3(g)) production

Role of NO₃ radical in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign

International audienceDuring the MINOS campaign (28 July?18 August 2001) nitrate (NO3) radical was measured at Finokalia, on the north coast of Crete in South-East Europe using a long path (10.4 km) Differential Optical Absorption Spectroscopy instrument (DOAS). Hydroxyl (OH) radical was also measured by a Chemical Ionization Mass-Spectrometer (Berresheim et al., this issue). These datasets represent the first simultaneous measurements of OH and NO3 radicals in the area. NO3 radical concentrations ranged from less than 3·107 up to 9·108 radical·cm-3 with an average value of 1.1·108 radical·cm?3. The observed NO3 mixing ratios are analyzed on the basis of the corresponding meteorological data and the volatile organic compound (VOC) observations simultaneously obtained at Finokalia station. The importance of the NO3 radical relatively to that of OH in the dimethylsulfide (DMS) and nitrate cycles is also investigated. The observed NO3 levels clearly regulate the diurnal variation of DMS. NO3 and N2O5 reactions account for about 21% of the total nitrate (HNO3(g) + NO?3(part)) production