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| Titel |
Lightning-produced NOx during the Northern Australian monsoon; results from the ACTIVE campaign |
| VerfasserIn |
L. Labrador, G. Vaughan, W. Heyes, D. Waddicor, A. Volz-Thomas, H.-W. Pätz, H. Höller |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 19 ; Nr. 9, no. 19 (2009-10-05), S.7419-7429 |
| Datensatznummer |
250007668
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| Publikation (Nr.) |
 copernicus.org/acp-9-7419-2009.pdf |
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| Zusammenfassung |
| Measurements of nitrogen oxides onboard a high altitude aircraft were
carried out for the first time during the Northern Australian monsoon in the
framework of the Aerosol and Chemical Transport in Tropical Convection
(ACTIVE) campaign, in the area around Darwin, Australia. During one flight
on 22 January 2006, average NOx volume mixing ratios (vmr) of 984 and
723 parts per trillion (ppt) were recorded for both in and out of cloud
conditions, respectively. The in-cloud measurements were made in the
convective outflow region of a storm 56 km south-west of Darwin, whereas
those out of cloud were made due south of Darwin and upwind from the storm
sampled. This storm produced a total of only 8 lightning strokes, as
detected by an in-situ lightning detection network, ruling out significant
lightning-NOx production. 5-day backward trajectories suggest that the
sampled airmasses had travelled over convectively-active land in Northern
Australia during that period. The low stroke count of the sampled storm,
along with the high out-of-cloud NOx concentration, suggest that, in
the absence of other major NOx sources during the monsoon season, a
combination of processes including regional transport patterns, convective
vertical transport and entrainment may lead to accumulation of
lightning-produced NOx, a situation that contrasts with the pre-monsoon
period in Northern Australia, where the high NOx values occur mainly in
or in the vicinity of storms. These high NOx concentrations may help
start ozone photochemistry and OH radical production in an otherwise
NOx-limited environment. |
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