Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, Chile
The knowledge of surface ozone mole fractions and their global distribution is of utmost importance due to the impact of ozone on human health and ecosystems and the central role of ozone in controlling the oxidation capacity of the troposphere. The availability of long-term ozone records is far bet...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2017-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/17/6477/2017/acp-17-6477-2017.pdf |
| _version_ | 1818913398857924608 |
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| author | J. G. Anet M. Steinbacher L. Gallardo P. A. Velásquez Álvarez L. Emmenegger B. Buchmann |
| author_facet | J. G. Anet M. Steinbacher L. Gallardo P. A. Velásquez Álvarez L. Emmenegger B. Buchmann |
| author_sort | J. G. Anet |
| collection | DOAJ |
| description | The knowledge of surface ozone mole fractions and their global distribution
is of utmost importance due to the impact of ozone on human health and
ecosystems and the central role of ozone in controlling the oxidation
capacity of the troposphere. The availability of long-term ozone records is
far better in the Northern than in the Southern Hemisphere, and recent
analyses of the seven accessible records in the Southern Hemisphere have
shown inconclusive trends. Since late 1995, surface ozone is measured in situ
at "El Tololo", a high-altitude (2200 m a.s.l.) and pristine
station in Chile (30° S, 71° W). The dataset has been
recently fully quality controlled and reprocessed. This study presents the
observed ozone trends and annual cycles and identifies key processes driving
these patterns. From 1995 to 2010, an overall positive trend of
∼ 0.7 ppb decade<sup>−1</sup> is found. Strongest trends per season
are observed in March and April. Highest mole fractions are observed in late
spring (October) and show a strong correlation with ozone transported from
the stratosphere down into the troposphere, as simulated with a model. Over
the 20 years of observations, the springtime ozone maximum has shifted to
earlier times in the year, which, again, is strongly correlated with a
temporal shift in the occurrence of the maximum of simulated stratospheric
ozone transport at the site. We conclude that background ozone at El Tololo
is mainly driven by stratospheric intrusions rather than photochemical
production from anthropogenic and biogenic precursors. The major footprint of
the sampled air masses is located over the Pacific Ocean. Therefore, due to
the negligible influence of local processes, the ozone record also allows
studying the influence of El Niño and La Niña episodes on background
ozone levels in South America. In agreement with previous studies, we find
that, during La Niña conditions, ozone mole fractions reach higher levels
than during El Niño conditions. |
| first_indexed | 2024-12-19T23:29:52Z |
| format | Article |
| id | doaj.art-616907dc7feb497ebcf4ab1f55332af4 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-19T23:29:52Z |
| publishDate | 2017-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-616907dc7feb497ebcf4ab1f55332af42022-12-21T20:01:46ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242017-05-0117106477649210.5194/acp-17-6477-2017Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, ChileJ. G. Anet0M. Steinbacher1L. Gallardo2P. A. Velásquez Álvarez3L. Emmenegger4B. Buchmann5Laboratory for Air Pollution/Environmental Technology, Swiss Federal Laboratories for Materials Science and Technology Empa, Duebendorf, SwitzerlandLaboratory for Air Pollution/Environmental Technology, Swiss Federal Laboratories for Materials Science and Technology Empa, Duebendorf, SwitzerlandDepartamento de Geofísica de la Universidad de Chile, Blanco Encalada 2002, piso 4, Santiago, ChileDirección Meteorológica de Chile, Av. Portales 3450, Estación Central, Santiago, ChileLaboratory for Air Pollution/Environmental Technology, Swiss Federal Laboratories for Materials Science and Technology Empa, Duebendorf, SwitzerlandLaboratory for Air Pollution/Environmental Technology, Swiss Federal Laboratories for Materials Science and Technology Empa, Duebendorf, SwitzerlandThe knowledge of surface ozone mole fractions and their global distribution is of utmost importance due to the impact of ozone on human health and ecosystems and the central role of ozone in controlling the oxidation capacity of the troposphere. The availability of long-term ozone records is far better in the Northern than in the Southern Hemisphere, and recent analyses of the seven accessible records in the Southern Hemisphere have shown inconclusive trends. Since late 1995, surface ozone is measured in situ at "El Tololo", a high-altitude (2200 m a.s.l.) and pristine station in Chile (30° S, 71° W). The dataset has been recently fully quality controlled and reprocessed. This study presents the observed ozone trends and annual cycles and identifies key processes driving these patterns. From 1995 to 2010, an overall positive trend of ∼ 0.7 ppb decade<sup>−1</sup> is found. Strongest trends per season are observed in March and April. Highest mole fractions are observed in late spring (October) and show a strong correlation with ozone transported from the stratosphere down into the troposphere, as simulated with a model. Over the 20 years of observations, the springtime ozone maximum has shifted to earlier times in the year, which, again, is strongly correlated with a temporal shift in the occurrence of the maximum of simulated stratospheric ozone transport at the site. We conclude that background ozone at El Tololo is mainly driven by stratospheric intrusions rather than photochemical production from anthropogenic and biogenic precursors. The major footprint of the sampled air masses is located over the Pacific Ocean. Therefore, due to the negligible influence of local processes, the ozone record also allows studying the influence of El Niño and La Niña episodes on background ozone levels in South America. In agreement with previous studies, we find that, during La Niña conditions, ozone mole fractions reach higher levels than during El Niño conditions.http://www.atmos-chem-phys.net/17/6477/2017/acp-17-6477-2017.pdf |
| spellingShingle | J. G. Anet M. Steinbacher L. Gallardo P. A. Velásquez Álvarez L. Emmenegger B. Buchmann Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, Chile Atmospheric Chemistry and Physics |
| title | Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, Chile |
| title_full | Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, Chile |
| title_fullStr | Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, Chile |
| title_full_unstemmed | Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, Chile |
| title_short | Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, Chile |
| title_sort | surface ozone in the southern hemisphere 20 years of data from a site with a unique setting in el tololo chile |
| url | http://www.atmos-chem-phys.net/17/6477/2017/acp-17-6477-2017.pdf |
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