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Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and western Africa

Tadic, Ivan; Nussbaumer, Clara M.; Bohn, Birger; Harder, Hartwig; Marno, Daniel; Martinez, Monica; Obersteiner, Florian 1; Parchatka, Uwe; Pozzer, Andrea; Rohloff, Roland; Zöger, Martin; Lelieveld, Jos; Fischer, Horst
1 Karlsruher Institut für Technologie (KIT)

Mechanisms of tropospheric ozone (O3) formation are generally well understood. However, studies reporting on net ozone production rates (NOPRs) directly derived from in situ observations are challenging and are sparse in number. To analyze the role of nitric oxide (NO) in net ozone production in the upper tropical troposphere above the Atlantic Ocean and western Africa, we present in situ trace gas observations obtained during the CAFE-Africa (Chemistry of the Atmosphere: Field Experiment in Africa) campaign in August and September 2018. The vertical profile of in situ measured NO along the flight tracks reveals lowest NO mixing ratios of less than 20 pptv between 2 and 8 km altitude and highest mixing ratios of 0.15–0.2 ppbv above 12 km altitude. Spatial distribution of tropospheric NO above 12 km altitude shows that the sporadically enhanced local mixing ratios (>0.4 ppbv) occur over western Africa, which we attribute to episodic lightning events. Measured O3 shows little variability in mixing ratios at 60–70 ppbv, with slightly decreasing and increasing tendencies towards the boundary layer and stratosphere, respectively. Concurrent measurements of CO, CH$_{4}$, OH, HO$_{2}$ and H$_{2}$O enable calculations of NOPRs along the flight tracks and reveal net ozone destruction at −0.6 to −0.2 ppbv h$^{-1}$ below 6 km altitude and balance of production and destruction around 7–8 km altitude. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000133838
Veröffentlicht am 14.06.2021
DOI: 10.5194/acp-21-8195-2021
Zitationen: 3
Web of Science
Zitationen: 3
Zitationen: 5
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung – Atmosphärische Spurenstoffe und Fernerkundung (IMK-ASF)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 27.05.2021
Sprache Englisch
Identifikator ISSN: 1680-7316, 1680-7324
KITopen-ID: 1000133838
HGF-Programm 12.11.13 (POF IV, LK 01) Long-term trends of global atmospheric composition
Erschienen in Atmospheric Chemistry and Physics
Verlag European Geosciences Union (EGU)
Band 21
Heft 10
Seiten 8195-8211
Nachgewiesen in Web of Science
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