Factors affecting the 7Be surface concentration and its extremely high occurrences over the Scandinavian Peninsula during autumn and winter. (May 2018)

• Record Type: Journal Article
• Authors: Ajtić, J.; Brattich, E.; Sarvan, D.; Djurdjevic, V.; Hernández-Ceballos, M.A.
• Is Part Of: Chemosphere. Volume 199(2018)
• Page Start: 278
• Page End: 285
• Publication Date: 2018-05
• Subjects: Beryllium-7 -- Surface air -- Meteorological parameters -- Teleconnection indices -- Multivariate analysis -- Sudden stratospheric warming; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.02.052
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Relationships between the beryllium-7 activity concentrations in surface air and meteorological parameters (temperature, atmospheric pressure, and precipitation), teleconnection indices (Arctic Oscillation, North Atlantic Oscillation, and Scandinavian pattern) and number of sunspots are investigated using two multivariate statistical techniques: hierarchical cluster and factor analysis. The beryllium-7 surface measurements over 1995–2011, at four sampling sites located in the Scandinavian Peninsula, are obtained from the Radioactivity Environmental Monitoring Database. In all sites, the statistical analyses show that the beryllium-7 concentrations are strongly linked to temperature. Although the beryllium-7 surface concentration exhibits the well-characterised spring/summer maximum, our study shows that extremely high beryllium-7 concentrations, defined as the values exceeding the 90 th percentile in the data records for each site, also occur over the October–March period. Two types of autumn/winter extremes are distinguished: type-1 when the number of extremes in a given month is less than three, and type-2 when at least three extremes occur in a month. Factor analysis performed for these autumn/winter events shows a weaker effect of temperature and a stronger impact of the transport and production signal on the beryllium-7 concentrations. Further, the majority of the type-2 extremes are associated with a very high monthly Scandinavian teleconnection index. The type-2 extremes that occurred in January, February and March are also linked to sudden stratospheric warmings of the Arctic vortex. Our results indicate that the Scandinavian teleconnection index might be a good indicator of the meteorological conditions facilitating extremely high beryllium-7 surface concentrations over Scandinavia during autumn and winter. Highlights: Factor analysis shows the strongest link between temperature and 7 Be concentration. Significant number of extremely high 7 Be concentrations occurs in autumn and winter. Autumn/winter 7 Be extremes seem more affected by transport and production. SCAND index might be a good indicator for occurrence of these 7 Be extremes. Some 7 Be winter extremes follow sudden stratospheric warmings of the Arctic vortex.