Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth century
The NO<sub><i>x</i></sub> (NO and NO<sub>2</sub>) and HO<sub><i>x</i></sub> (OH and HO<sub>2</sub>) budgets of the atmosphere exert a major influence on atmospheric composition, controlling removal of primary pollutants and fo...
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doaj-b549c90f725f46e6ac07f40fc6198c0c2020-11-24T22:43:57ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242017-07-01178269828310.5194/acp-17-8269-2017Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth centuryM. J. Newland0P. Martinerie1P. Martinerie2E. Witrant3D. Helmig4D. R. Worton5C. Hogan6W. T. Sturges7C. E. Reeves8Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, UKUniv. Grenoble Alpes/CNRS, LGGE, 38000 Grenoble, Francenow at: Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York, UKUniv. Grenoble Alpes/CNRS, GIPSA-Lab, 38000 Grenoble, FranceInstitute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USANational Physical Laboratory, Teddington, Middlesex, UKCentre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, UKCentre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, UKCentre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, UKThe NO<sub><i>x</i></sub> (NO and NO<sub>2</sub>) and HO<sub><i>x</i></sub> (OH and HO<sub>2</sub>) budgets of the atmosphere exert a major influence on atmospheric composition, controlling removal of primary pollutants and formation of a wide range of secondary products, including ozone, that can influence human health and climate. However, there remain large uncertainties in the changes to these budgets over recent decades. Due to their short atmospheric lifetimes, NO<sub><i>x</i></sub> and HO<sub><i>x</i></sub> are highly variable in space and time, and so the measurements of these species are of limited value for examining long-term, large-scale changes to their budgets. Here, we take an alternative approach by examining long-term atmospheric trends of alkyl nitrates, the production efficiency of which is dependent on the atmospheric [NO] ∕ [HO<sub>2</sub>] ratio. We derive long-term trends in the alkyl nitrates from measurements in firn air from the NEEM site, Greenland. Their mixing ratios increased by a factor of 3–5 between the 1970s and 1990s. This was followed by a steep decline to the sampling date of 2008. Moreover, we examine how the trends in the alkyl nitrates compare to similarly derived trends in their parent alkanes (i.e. the alkanes which, when oxidised in the presence of NO<sub><i>x</i></sub>, lead to the formation of the alkyl nitrates). The ratios of the alkyl nitrates to their parent alkanes increased from around 1970 to the late 1990s. This is consistent with large changes to the [NO] ∕ [HO<sub>2</sub>] ratio in the Northern Hemisphere atmosphere during this period. Alternatively, they could represent changes to concentrations of the hydroxyl radical, OH, or to the transport time of the air masses from source regions to the Arctic.https://www.atmos-chem-phys.net/17/8269/2017/acp-17-8269-2017.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
M. J. Newland P. Martinerie P. Martinerie E. Witrant D. Helmig D. R. Worton C. Hogan W. T. Sturges C. E. Reeves |
spellingShingle |
M. J. Newland P. Martinerie P. Martinerie E. Witrant D. Helmig D. R. Worton C. Hogan W. T. Sturges C. E. Reeves Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth century Atmospheric Chemistry and Physics |
author_facet |
M. J. Newland P. Martinerie P. Martinerie E. Witrant D. Helmig D. R. Worton C. Hogan W. T. Sturges C. E. Reeves |
author_sort |
M. J. Newland |
title |
Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth century |
title_short |
Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth century |
title_full |
Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth century |
title_fullStr |
Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth century |
title_full_unstemmed |
Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth century |
title_sort |
changes to the chemical state of the northern hemisphere atmosphere during the second half of the twentieth century |
publisher |
Copernicus Publications |
series |
Atmospheric Chemistry and Physics |
issn |
1680-7316 1680-7324 |
publishDate |
2017-07-01 |
description |
The NO<sub><i>x</i></sub> (NO and NO<sub>2</sub>) and HO<sub><i>x</i></sub> (OH and HO<sub>2</sub>)
budgets of the atmosphere exert a major influence on atmospheric composition,
controlling removal of primary pollutants and formation of a wide range of
secondary products, including ozone, that can influence human health and
climate. However, there remain large uncertainties in the changes to these
budgets over recent decades. Due to their short atmospheric lifetimes,
NO<sub><i>x</i></sub> and HO<sub><i>x</i></sub> are highly variable in space and time, and so the
measurements of these species are of limited value for examining long-term,
large-scale changes to their budgets. Here, we take an alternative approach
by examining long-term atmospheric trends of alkyl nitrates, the production
efficiency of which is dependent on the atmospheric [NO] ∕ [HO<sub>2</sub>]
ratio. We derive long-term trends in the alkyl nitrates from measurements in
firn air from the NEEM site, Greenland. Their mixing ratios increased by a
factor of 3–5 between the 1970s and 1990s. This was followed by a steep
decline to the sampling date of 2008. Moreover, we examine how the trends in
the alkyl nitrates compare to similarly derived trends in their parent
alkanes (i.e. the alkanes which, when oxidised in the presence of NO<sub><i>x</i></sub>,
lead to the formation of the alkyl nitrates). The ratios of the alkyl
nitrates to their parent alkanes increased from around 1970 to the late
1990s. This is consistent with large changes to the [NO] ∕ [HO<sub>2</sub>]
ratio in the Northern Hemisphere atmosphere during this period.
Alternatively, they could represent changes to concentrations of the hydroxyl
radical, OH, or to the transport time of the air masses from source regions
to the Arctic. |
url |
https://www.atmos-chem-phys.net/17/8269/2017/acp-17-8269-2017.pdf |
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