22 Aug 2023
 | 22 Aug 2023

UV solar radiation climatology and its behaviour during events of influence of the Antarctic ozone hole over south of Brazil

Bibiana Lopes, Damaris Kirsch Pinheiro, Hassan Bencherif, Gabriela Dornelles Bittencourt, Lucas Vaz Peres, Jean-Maurice Cadet, Thierry Portafaix, and Nathalie Tissot Boiaski

Abstract. Ultraviolet solar radiation that reaches the surface of the Earth has a very important role in the energy budget of our planet, although at certain amounts of exposure it can be harmful not only for human health, but animals and plants. Brazil is a tropical country receiving high intensity of UV radiation mostly of the year. UV radiation, specially UV-B is mainly absorbed in the ozone layer, changes in ozone content or ozone distribution directly affects UV radiation attenuation, so that surface UV. Ozone hole is characterized by an intense ozone depletion in the stratosphere in Antarctic region, happening during spring in the south hemisphere. There is evidence of poor-ozone air masses detachment from polar vortex and reaching mid-latitude regions, such as South of Brazil. Those air masses cause impact on the regions which they act due to low ozone content, allowing more radiation to reach the surface. UV index data from a Brewer Spectrophotometer (MKIII #167), located in south of Brazil, in the Southern Space Observatory (29.42° S, 53.87° W) was analysed with data collected between 2005 and 2017. Ground data was compared to satellite-derived from OMI/Aura, resulting in a correlation coefficient of 0.95 %. The climatology of Brewer data was done, analysing seasonal and interannual variability. Wavelet analysis showed the influence of ENSO, QBO and solar cycle on the variability of UV index. The results show a typical seasonal behaviour of UV Index, reaching extreme during summer season. Events of secondary effects of Antarctic ozone hole, identified between 2005 and 2016 (Bittencourt, 2018), were selected and the behavior of UV index and UV-B non-weighted during those events were studied. All ten events studied showed a significant increase in UV radiation at the days of events, the majority resulted in an increase of 4 % of UV index for each 1 % ozone total column decrease. One specific event was described in detail due to the major ozone depletion. Occurred in October 2016, ozone depletion was of almost 20 % while UV index increased 88 % in relation to the climatological mean, raising the concern with public health regarding excess exposure to UV radiation.

Bibiana Lopes 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-2023-1474', Jochen Wagner, 09 Oct 2023
  • Statistical Analysis:
    • Criticism: The correlation coefficient of 0.95% between ground data and satellite-derived data is mentioned, but there's no elaboration on the statistical tests used, the significance level, or the confidence intervals.
    • Suggestion: The authors should employ rigorous statistical tests, such as Pearson's or Spearman's rank correlation, and report p-values. Additionally, scatter plots with regression lines could visually represent the correlation.
  • Analysis of Atypical Behavior of Ozone Hole:
    • Criticism: The paper notes an atypical behavior of the ozone hole in the years 2020, 2021, and 2022 but doesn't provide a comparative analysis with previous years or a clear methodology on how this atypical behavior was determined.
    • Suggestion: A time-series analysis comparing the ozone hole's behavior over the past decades would provide context. The authors should also consider using anomaly detection techniques to statistically determine the atypical behavior.
  • Influence of QBO, ENSO, and Solar Cycle:
    • Criticism: The manuscript touches upon the influence of QBO, ENSO, and the solar cycle on UV radiation but lacks depth in the methodology used to determine these influences.
    • Suggestion: The authors should consider multivariate regression or time-series decomposition to isolate and quantify the effects of QBO, ENSO, and the solar cycle on UV radiation. This would provide a clearer picture of each factor's contribution.
  • Secondary Effects of Antarctic Ozone Hole:
    • Criticism: The paper mentions secondary effects of the Antarctic ozone hole but doesn't elaborate on how these effects were identified or measured.
    • Suggestion: A clear methodology on how these secondary effects were determined is essential. Only using HSPLIT trajectory analysis or any other modeling technique is not enough.
  • General Analysis Improvements:
    • Criticism: The manuscript lacks high quality visual representations of the data. Some graphs give almost no new information to the reader, since the same time series is shown again. Plotting the typical diurnal cycle of UV-Index simply show the dependence on solar zenith angle.
    • Suggestion: The climatology plot should show daily/monthly mean, median, min, max values and the variability. Visual representations can often convey findings more effectively than textual descriptions alone, but again, like in the text the interesting findings are hidden by not meaningful graphs.

    In summary, while the manuscript touches upon significant points, it requires a more rigorous and detailed approach in its methodology and analysis to meet the standards of scientific research. The authors should consider revisiting each section, ensuring clarity, depth, and scientific rigor.

  • RC2: 'Comment on egusphere-2023-1474', Sasha Madronich, 10 Oct 2023
    • AC1: 'Reply on RC2', Bibiana Lopes, 07 Dec 2023
  • AC2: 'Comment on egusphere-2023-1474', Bibiana Lopes, 07 Dec 2023
  • Bibiana Lopes et al.

    Bibiana Lopes et al.


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    Short summary
    This is a study of the climatology and behavior of UV radiation on the surface during events of secondary effects of the Antarctic ozone hole over south of Brazil. Considering all implications of excess exposure to UV radiation on the surface on human health it is important to know how much radiation the population is being exposed to during those events. Results showed that for each 1 % decrease in the ozone total column, the UV index tends to increase by 4 % in the region of study.