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- Title
Quantification of the unknown HONO daytime source and its relation to NO<sub>2</sub>.
- Authors
Sörgel, M.; Regelin, E.; Bozem, H.; Diesch, J.-M.; Drewnick, F.; Fischer, H.; Harder, H.; Held, A.; Hosaynali-Beygi, Z.; Martinez, M.; Zetzsch, C.
- Abstract
During the DOMINO (Diel Oxidant Mechanism In relation to Nitrogen Oxides) campaign in southwest Spain we measured simultaneously all quantities necessary to calculate a photostationary state for HONO in the gas phase. These quantities comprise the concentrations of OH, NO, and HONO and the photolysis frequency of NO2, j(NO2) as a proxy for j(HONO). This allowed us to calculate values of the unknown HONO daytime source. This unknown HONO source, normalized by NO2 mixing ratios and expressed as a conversion frequency (% h-1), showed a clear dependence on j(NO2) with values up to 43%h-1 at noon. We compared our unknown HONO source with values calculated from the measured field data for two recently proposed processes, the light-induced NO2 conversion on soot surfaces and the reaction of electronically excited NO2 with water vapour, with the result that these two reactions normally contributed less than 10% (<1% NO2 + soot + hv; and <10% NO2* +H2O) to our unknown HONO daytime source. OH production from HONO photolysis was found to be larger (by 20 %) than the "classical" OH formation from ozone photolysis (O(¹D)) integrated over the day.
- Subjects
SPAIN; NITROGEN dioxide; PHOTOLYSIS (Chemistry); OXIDIZING agents; REACTION mechanisms (Chemistry); COMPARATIVE studies; OZONE
- Publication
Atmospheric Chemistry & Physics, 2011, Vol 11, Issue 20, p10433
- ISSN
1680-7316
- Publication type
Article
- DOI
10.5194/acp-11-10433-2011