Inter-annual variability of surface ozone at coastal (Dumont d'Urville, 2004–2014) and inland (Concordia, 2007–2014) sites in East Antarctica
Surface ozone has been measured since 2004 at the coastal East Antarctic site of Dumont d'Urville (DDU), and since 2007 at the Concordia station located on the high East Antarctic plateau. This paper discusses long-term changes, seasonal and diurnal cycles, as well as inter-annual summer va...
Main Authors: | , , , , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2016-07-01
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Series: | Atmospheric Chemistry and Physics |
Online Access: | https://www.atmos-chem-phys.net/16/8053/2016/acp-16-8053-2016.pdf |
Summary: | Surface ozone has been measured since 2004 at the coastal East Antarctic
site of Dumont d'Urville (DDU), and since 2007 at the Concordia station
located on the high East Antarctic plateau. This paper discusses long-term
changes, seasonal and diurnal cycles, as well as inter-annual summer
variability observed at these two East Antarctic sites. At Concordia, near-surface
ozone data were complemented by balloon soundings and compared to
similar measurements done at the South Pole. The DDU record is compared to
those obtained at the coastal site of Syowa, also located in East
Antarctica, as well as the coastal sites of Neumayer and Halley, both
located on the coast of the Weddell Sea in West Antarctica. Surface ozone
mixing ratios exhibit very similar seasonal cycles at Concordia and the
South Pole. However, in summer the diurnal cycle of ozone is different at
the two sites with a drop of ozone in the afternoon at Concordia but not at
the South Pole. The vertical distribution of ozone above the snow surface
also differs. When present, the ozone-rich layer located near the ground is
better mixed and deeper at Concordia (up to 400 m) than at the South Pole
during sunlight hours. These differences are related to different solar
radiation and wind regimes encountered at these two inland sites. DDU
appears to be the coastal site where the impact of the late winter/spring
bromine chemistry is the weakest, but where the impact of elevated ozone
levels caused by NO<sub><i>x</i></sub> snow emissions from the high Antarctic plateau is
the highest. The highest impact of the bromine chemistry is seen at Halley
and Neumayer, and to a lesser extent at Syowa. These three sites are only
weakly impacted by the NO<sub><i>x</i></sub> chemistry and the net ozone production
occurring on the high Antarctic plateau. The differences in late
winter/spring are attributed to the abundance of sea ice offshore from the sites,
whereas those in summer are related to the topography of East Antarctica
that promotes the katabatic flow bringing oxidant-rich inland air masses to
the site. There appears to be a decreasing change in summer surface ozone at
the two East Antarctic sites of Concordia and DDU over the most recent
period (2004–2014 and 2007–2014). Further research, including continued monitoring,
is needed at these two sites to better separate the effect of synoptic
transport from possible change of NO<sub><i>x</i></sub> snow emissions in response to
recovery of the stratospheric ozone layer leading to penetration of more UV
radiation to the surface. |
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ISSN: | 1680-7316 1680-7324 |