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

M. Vrekoussis (1) , M. Kanakidou (1) , N. Mihalopoulos (1) , P. J. Crutzen (2) , J. Lelieveld (2) , D. Perner (2) , H. Berresheim (3) , E. Baboukas (2)

1 ECPL - Environmental Chemical Processes Laboratory [Heraklion]
2 MPIC - Max-Planck-Institut für Chemie
3 DWD - Deutscher Wetterdienst [Offenbach]

During 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 (HNO_3(g) + NO^?_3(part)) production.

Domaines: Océan, Atmosphère

M. Vrekoussis, M. Kanakidou, N. Mihalopoulos, P. J. Crutzen, J. Lelieveld, et al.. Role of NO₃ radical in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign. Atmospheric Chemistry and Physics Discussions, 2003, 3 (3), pp.3135-3169. ⟨hal-00301104⟩