27 Mar 2023
 | 27 Mar 2023

Investigation of meteorological conditions and BrO during Ozone Depletion Events in Ny-Ålesund between 2010 and 2021

Bianca Zilker, Andreas Richter, Anne-Marlene Blechschmidt, Peter von der Gathen, Ilias Bougoudis, Sora Seo, Tim Bösch, and John Philip Burrows

Abstract. During polar spring, Ozone Depletion Events (ODEs) are often observed in combination with Bromine Explosion Events (BEEs) in Ny-Ålesund. In this study, two long term ozone data sets (2010–2021) from ozone sonde launches and in-situ ozone measurements have been evaluated between March and May of each year, to study ODEs in Ny-Ålesund. Ozone concentrations below 15 ppb were marked as ODE. We applied a composite analysis to evaluate tropospheric BrO retrieved from satellite data and the prevailing meteorological conditions during these events. During ODEs, both data sets show a blocking situation with a low pressure anomaly over the Barents Sea and anomalously high pressure in the Icelandic low area, leading to transport of cold polar air from the north to Ny-Ålesund with negative temperature and positive BrO anomalies found around Svalbard. Also higher wind speed and a higher, less stable boundary layer are noticed, supporting the assumption that ODEs often occur in combination with polar cyclones. Applying a 20 ppb ozone threshold value to tag ODEs resulted in only a slight attenuation of the BrO and meteorological anomalies compared to the 15 ppb threshold. Monthly analysis showed that BrO and meteorological anomalies are weakening from March to May. Therefore, ODEs associated with low pressure systems, high wind speeds and blowing snow more likely occur in early spring, while ODEs associated with low wind speed and stable boundary layer meteorological conditions seem to occur more often in late spring. In an annual evaluation, similar prevailing meteorological conditions were found for several years as well as in the overall result of the composite analysis. However, some years show different meteorological patterns deviating from the results of the mean analysis. Finally, an ODE case study from the beginning of April 2020 in Ny-Ålesund is presented, where ozone was depleted for two consecutive days in combination with increased BrO values. The meteorological conditions are representative of the results of the composite analysis. A low pressure system arrived from the north-east to Svalbard resulting in high wind speeds with blowing snow and transport of cold polar air from the north.

Bianca Zilker et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-522', Anonymous Referee #1, 17 Apr 2023
  • RC2: 'Comment on egusphere-2023-522', Anonymous Referee #2, 19 Apr 2023

Bianca Zilker et al.

Bianca Zilker et al.


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Short summary
During Arctic spring, near-surface ozone is depleted by bromine released from salty sea ice and/or snow covered areas under certain meteorological conditions. To study this ozone depletion and the prevailing meteorological conditions, two ozone data sets from Ny-Ålesund, Svalbard have been evaluated. We found, that during ozone depletion events, lower pressure over the Barents Sea and higher pressure in the Icelandic low area lead to a transport of cold polar air from the north to Ny-Ålesund.