Year-round record of near-surface ozone and O<sub>3</sub> enhancement events (OEEs) at Dome A, East Antarctica

Abstract

<p><strong>Abstract.</strong> To evaluate the characteristics of near-surface O<sub>3</sub> over Dome A (Kunlun Station), which is located at the summit of the east Antarctic Ice Sheet, continuous observations were carried out in 2016. Together with observations from the Amundsen–Scott Station (South Pole) and Zhongshan Station, the seasonal and diurnal O<sub>3</sub> 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 were 29.19 ± 7.52 ppb, 29.94 ± 4.97 ppb and 24.06 ± 5.79 ppb. Then, specific atmospheric processes, including synoptic-scale air mass transport, were analysed by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back-trajectory analysis and the potential source contribution function (PSCF) model. Long-range transport was found to account for the O<sub>3</sub> enhancement events (OEEs) during summer at Dome A, rather than efficient local production (consistent with previous studies in inland Antarctica). In addition, we observed OEEs during the polar night in the Dome A region, which was not previously found in Antarctica. To explain this unique finding, the occurrence of stratospheric intrusion (stratosphere-to-troposphere, STT) events was studied with the Stratosphere-to-Troposphere Exchange Flux (STEFLUX) tool. This finding suggested that STT events occurred frequently over Dome A and could account for 55 % of the total polar night period. The occurrence probability of OEEs agreed well with STT events, indicating that the STT process was the dominant factor affecting the near-surface O<sub>3</sub> over Dome A in the absence of photochemical reaction sources during polar night. This work provides unique information on ozone variation at Dome A and expands our knowledge regarding such events in Antarctica.</p>

Air quality improvement during triple-lockdown in the coastal city of Kannur, Kerala to combat Covid-19 transmission

“…Particulate matters (PM 10 and PM 2.5 ), oxides of nitrogen (NO and NO 2 ), sulfur dioxide (SO 2 ), ozone (O 3 ), carbon monoxide (CO) and volatile organic compounds (VOC’s) are the most common atmospheric air pollutants encountered in our daily life ( Chen & Kan, 2008 ; Guo et al, 2019 ). At the ground level, O 3 is a major secondary air pollutant and greenhouse gas, produced from its precursor gases in the presence of solar radiation, and it plays a crucial role in air quality ( Yadav et al, 2016 ; Lu et al, 2018 ; Ding et al, 2020 ; Maji, Beig & Yadav, 2020 ; Resmi et al, 2020 ). Particulate matters are complex mixture of organic and inorganic substances found in the ambient air, and they play a vital role in the radiation budget of the atmosphere via the scattering and absorption processes ( Qu et al, 2017 , 2018 ).…”

Peer Review #2 of "Air quality improvement during triple-lockdown in the coastal city of Kannur, Kerala to combat Covid-19 transmission (v0.1)"

“…Particulate matters (PM 10 and PM 2.5 ), oxides of nitrogen (NO and NO 2 ), sulfur dioxide (SO 2 ), ozone (O 3 ), carbon monoxide (CO), and volatile organic compounds (VOC's) are the most common atmospheric air pollutants encountered in our daily life (Chen and Kan 2008;Guo et al 2019). At the ground level, O 3 is a major secondary air pollutant and greenhouse gas, produced from its precursor gases in the presence of solar radiation, and it plays a crucial role in air quality (Yadav et al 2016;Lu et al 2018;Ding et al 2020;Maji et al 2020;Resmi et al 2020). Particulate matters are complex mixture of organic and inorganic substances found in the ambient air, and they play a vital role on the radiation budget of the atmosphere via the scattering and absorption processes (Qu et al 2017;Qu et al 2018).…”