Year-round record of near-surface ozone and O₃ enhancement events (OEEs) at Dome A, East Antarctica

Abstract

Abstract. Dome A, the summit of the East Antarctic Ice Sheet, is an area challenging to access and is one of the harshest environments on Earth. Up until recently, long-term automated observations from Dome A (DA) were only possible with very low power instruments such as a basic meteorological station. To evaluate the characteristics of near-surface O3, continuous observations were carried out in 2016. Together with observations at the Amundsen–Scott Station (South Pole – SP) and Zhongshan Station (ZS, on the southeast coast of Prydz Bay), the seasonal and diurnal O3 variabilities were investigated. The results showed different patterns between coastal and inland Antarctic areas that were characterized by high concentrations in cold seasons and at night. The annual mean values at the three stations (DA, SP and ZS) were 29.2±7.5, 29.9±5.0 and 24.1±5.8 ppb, respectively. We investigated the effect of specific atmospheric processes on near-surface summer O3 variability, when O3 enhancement events (OEEs) are systematically observed at DA (average monthly frequency peaking at up to 64.5 % in December). As deduced by a statistical selection methodology, these O3 enhancement events (OEEs) are affected by significant interannual variability, both in their average O3 values and in their frequency. To explain part of this variability, we analyzed the OEEs as a function of specific atmospheric processes: (i) the role of synoptic-scale air mass transport over the Antarctic Plateau was explored using the Lagrangian back-trajectory analysis Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) method, and (ii) the occurrence of “deep” stratospheric intrusion events was investigated using the Lagrangian tool STEFLUX. The specific atmospheric processes, including synoptic-scale air mass transport, were analyzed by the HYSPLIT back-trajectory analysis and the potential source contribution function (PSCF) model. Short-range transport accounted for the O3 enhancement events (OEEs) during summer at DA, rather than efficient local production, which is consistent with previous studies of inland Antarctica. Moreover, the identification of recent (i.e., 4 d old) stratospheric-intrusion events by STEFLUX suggested that deep events only had a minor influence (up to 1.1 % of the period, in August) on deep events during the variability in near-surface summer O3 at DA. The deep events during the polar night were significantly higher than those during the polar day. This work provides unique data on ozone variation at DA and expands our knowledge of such events in Antarctica. Data are available at https://doi.org/10.5281/zenodo.3923517 (Ding and Tian, 2020).

Significant Latitudinal Gradient of Nitrate Production in the Marine Atmospheric Boundary Layer of the Northern Hemisphere

“…This may be associated with the distinct environments of the two polar regions. On the Antarctic ice sheet (70–80°S), the oxidative capacity of the boundary layer is significantly influenced by snow NO 3 − photolysis in austral summer (Davis et al., 2004; Legrand et al., 2009), which can result in enhanced concentrations of near‐surface O 3 (e.g., ∼24 ppb at Dome A; Ding et al., 2020). In contrast, in the Arctic Region, the oxidants from the oceans such as OH and HO 2 /RO 2 compete with O 3 in the production of atmospheric NO 3 − , resulting in relatively lower Δ 17 O‐NO 3 − .…”

“…During the sampling period, the meteorological data were obtained from the shipboard automatic weather station, and surface O 3 concentrations were measured every minute using a UV‐absorption near‐surface O 3 analyzer (EC9810A; for details refer to Ding et al. (2020)).…”

“…After sample collection, all filters were kept in clean opaque polythene (PE) bags, and preserved at −20 o C. Note that all handlers wore clean PE gloves and face masks to minimize the potential contamination during the sampling process. During the sampling period, the meteorological data were obtained from the shipboard automatic weather station, and surface O 3 concentrations were measured every minute using a UV-absorption near-surface O 3 analyzer (EC9810A; for details refer to Ding et al (2020)).…”

The Dominant Role of Brewer‐Dobson Circulation on 17O‐Excess Variations in Snow Pits at Dome A, Antarctica

“…It is characterized by extreme climate conditions, with an annual mean temperature of −58.3°C and a snow accumulation rate of 23 mm a −1 (Hou et al., 2007). In addition, Dome A is located in the core area of the Antarctic vortex, which makes it susceptible to stratospheric input (Ding et al., 2021). As a result, the 17 O‐excess in snow and ice at Dome A could be significantly influenced by the addition of stratospheric water.…”