Year-round measurements of nitrogen oxides and ozone in the tropical North Atlantic marine boundary layer
A highly sensitive chemiluminescence instrument has been deployed to measure nitric oxide (NO) and nitrogen dioxide (NO2) at the Cape Verde Atmospheric Observatory in the remote tropical North Atlantic marine boundary layer (MBL). Using two different methods, the instrument was assessed to have a de...
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Published in | Journal of Geophysical Research. B. Solid Earth Vol. 114; no. D21 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Washington, DC
Blackwell Publishing Ltd
05.11.2009
American Geophysical Union |
Subjects | |
Online Access | Get full text |
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Summary: | A highly sensitive chemiluminescence instrument has been deployed to measure nitric oxide (NO) and nitrogen dioxide (NO2) at the Cape Verde Atmospheric Observatory in the remote tropical North Atlantic marine boundary layer (MBL). Using two different methods, the instrument was assessed to have a detection limit of around 1.8 parts per trillion by volume (pptv) for NO and 5.5 pptv for NO2 for hour‐long integration periods. The overall accuracy was estimated at ∼18% for NO and 30% for NO2. Measurements of NO, NO2, and ozone (O3) over a period of 12 months in 2007 show very low levels of NOx (typically <30 pptv) and net daytime ozone destruction on most days of the measurement period. Air originating over Africa exhibited the highest levels of NOx (∼35 pptv) and reduced daily O3 destruction, with O3 production observed on a few days. Air that had not originated over Africa showed lower NOx levels (∼25 pptv), with greater observed O3 destruction. A dependence of the observed O3 destruction on NO mixing ratios, averaged over all air masses, was observed and reproduced using a simple box model. The model results imply that the presence of between 17 and 34 pptv of NO (depending on the month) would be required to turn the tropical North Atlantic from an O3 destroying to an O3 producing regime. |
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Bibliography: | istex:C49C0C5D772691C487C2E3A72965AAE691797E60 ArticleID:2009JD011878 Tab-delimited Table 1. ark:/67375/WNG-6RZX3TPZ-R 10.1029/2009JD011879 This is a commentary on DOI ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 |
ISSN: | 0148-0227 2169-897X 2156-2202 2169-8996 |
DOI: | 10.1029/2009JD011878 |