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

[摘要] During the MINOS campaign (28July-18 August 2001) the nitrate (NO₃) radical was measured at Finokalia station, on the north coast of Crete inSouth-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 simultaneousmeasurements of OH and NO₃ radicals in the area.NO₃ radicalconcentrations ranged from less than 3x10⁷ up to 9x10⁸radicals· cm^-3 with an average nighttime value of 1.1x10⁸radicals· cm^-3.

The observed NO₃ mixing ratios are analyzed on the basis of thecorresponding meteorological data and the volatile organic compound (VOC) observations which were measured simultaneously at Finokalia station. Theimportance of the NO₃ radical chemistry relatively to that of OH in thedimethylsulfide (DMS) and nitrate cycles is also investigated. The observedNO₃ levels regulate the nighttime variation of DMS. The loss of DMS byNO₃ during night is about75% of that by OH radical during day. NO₃ and nitrogen pentoxide(N₂O₅) reactions account for about21% of the total nitrate (HNO_3(g)+NO^-_3(g))production.

[学科分类] 大气科学