Inter-annual variability of surface ozone at coastal (Dumont d’Urville, 2004–2014) and inland (Concordia, 2007–2014) sites in East Antarctica

Abstract

<p><strong>Abstract.</strong> 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 trends, 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 at the coast of the Weddell Sea in West Antarctica. Surface ozone mixing ratios exhibit very similar seasonal cycle at Concordia and the South Pole. However, in summer the diurnal cycle and the vertical distribution of ozone above the snow surface are different at the two sites with a drop of ozone in the afternoon at Concordia and not at the South Pole, and a far well-mixed rich ozone layer within the lower 250 m at Concordia 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 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 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 trend in summer at the two East Antarctic sites of Concordia and DDU over the most recent period (2004/2007–2014). Further researches including continuing monitoring are needed at these two sites to better separate effect of synoptic transport from possible change of NO<sub><i>x</i></sub> snow emissions in response to change of the stratospheric ozone layer.</p>

Multi-year record of atmospheric mercury at Dumont d'Urville, East Antarctic coast: continental outflow and oceanic influences

“…Given its geographic location, DDU in Adélie Land lies close to a confluence zone explaining the extent of the transport of air masses from the Antarctic plateau. Conversely, several studies showed that stations such as NM and HA are not significantly impacted by air masses originating from the Antarctic plateau Legrand et al, 2016b), consistently explaining why Hg(0) concentrations did not decrease at NM and TR throughout winter (Ebinghaus et al, 2002;Pfaffhuber et al, 2012).…”

“…2) and we can just emphasize that the absence of Hg(0) drops in October 2012 tends to suggest that AMDEs, if exist, are not very frequent at DDU. Ozone depletion events (ODEs) are found to be less frequent and far less pronounced at DDU compared to other coastal stations such as NM and HA (Legrand et al, 2009(Legrand et al, , 2016b. Based on the oxygen and nitrogen isotope composition of airborne nitrate at DDU, concluded to an absence of significant implication of BrO in the formation of nitric acid at this site, contrarily to what is usually observed in the Arctic where high levels of BrO are measured at polar sunrise (Morin et al, 2008).…”

“…2.2.3). Legrand et al (2001Legrand et al ( , 2016b observed increasing atmospheric dimethylsulfide (DMS) and chloride concentrations, respectively, during sea breeze events. However, our results indicate that Hg(0) concentrations did not tend to increase systematically with the occurrence of a sea breeze (e.g., Fig.…”

Dry Deposition of Ozone Over Land: Processes, Measurement, and Modeling

“…Snowpack is not a location of ozone production: Ozone in snowpack interstitial air is generally depleted compared to above the surface (Albert et al, ; Bocquet et al, ; Helmig, Bocquet, et al, ; Peterson & Honrath, ; Seok et al, ), and ozone is always destroyed in snow chamber experiments (Aldaz, ; Bottenheim et al, ). However, ozone production in the poorly mixed layer right above snow may occur following the accumulation of ozone precursor emissions from the snowpack and enhanced irradiance from snow (e.g., Crawford et al, ; Cristofanelli et al, ; Helmig et al, ; Legrand et al, , ).…”

Oxygen isotope mass balance of atmospheric nitrate at Dome C, East Antarctica, during the OPALE campaign

“…This process is initiated by the photolysis of nitrate, which can lead to large fluxes of NO 2 , NO, and HONO from permanently sunlit snow (Anastasio and Chu, 2009;Grannas et al, 2007;Jacobi and Hilker, 2007;Legrand et al, 2014;Frey et al, 2013). Observed and modeled NO x production rates are largely capable of explaining the high levels of photochemical activity observed on the Antarctic Plateau during spring (France et al, 2011;Liao and Tan, 2008;Wang et al, 2007) although detailed and speciation of nitrogen oxides chemistry remain largely unknown in this NO x -rich/VOC-poor environment (Kukui et al, 2014;Frey et al, 2015;Legrand et al, 2014;Davis et al, 2008).…”