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Distribution of 7Be in surface air of Europe
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
Swedish Defence Research Agency, FOI, S-172 90 Stockholm, Sweden.
2006 (English)In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 40, no 21, 3855-3868 p.Article in journal (Refereed) Published
Abstract [en]

This study deals with long-term (span over three decades, 1972-2003) distribution of the cosmogenic isotope Be-7 in surface air at 5 stations in Europe, extending from latitude 47 degrees N to 68 degrees N. The results suggest annual variability in all the data sets as well as a decrease in average Be-7 activity with increasing latitude. Furthermore, a 9-10-year cyclical pattern is observed in the Be-7 distribution, which is anticorrelated with the solar activity cycle. Our data also indicate a dynamic range of Be-7 activity for each solar cycle and phase (maximum or minimum) which is higher at the middle compared to high-latitude regions. Additionally, about 10-20% relative deviation is observed in Be-7 activity during solar maxima and minima compared to the total average Be-7. This feature indicates that some deviation in the worldwide Be-7 activity data may relate to their acquisition, with respect to which part of a solar cycle they have been collected in (time span) and at which latitudinal spread. Estimate of Be-7 flux onto European surface boundary layer vary from 0.4 to 0.9 x 10(10) atoms m(-2) yr(-1) which is strongly latitude dependent and our average value is comparable to the similar to 0.7-0.8 x 10(10) atoms m(-2) yr(-1) across ocean and land.

Place, publisher, year, edition, pages
2006. Vol. 40, no 21, 3855-3868 p.
Keyword [en]
atmosphere; cosmogenic Be-7; Europe; solar activity; Sweden
National Category
Ecology Meteorology and Atmospheric Sciences
URN: urn:nbn:se:uu:diva-96040DOI: 10.1016/j.atmosenv.2006.02.030ISI: 000238827200004OAI: oai:DiVA.org:uu-96040DiVA: diva2:170459
Available from: 2007-05-15 Created: 2007-05-15 Last updated: 2016-08-25Bibliographically approved
In thesis
1. Atmospheric Production and Transport of Cosmogenic 7Be and 10Be
Open this publication in new window or tab >>Atmospheric Production and Transport of Cosmogenic 7Be and 10Be
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with the atmospheric distribution of the cosmogenic isotopes 7Be (half-life 53 days) and 10Be (half-life 1.51 million years) as well as the anthropogenic isotope 137Cs (half-life 30 years) in aerosols and precipitation. Samples covering continuous or selected parts of the period 1972-2005 in Sweden and Europe are evaluated with respect to production, air mass transport and fallout processes. Such information is valuable in assessing the potential of these isotopes as indicators of air mass mixing and solar modulation factors that affect climate change. The results of 7Be and 10Be show seasonal variability and an 11-year cyclic pattern which is anti-correlated with the solar activity. Variations in seasonal trends of 7Be and 137Cs in aerosols during the post- and pre-Chernobyl period reflect tropospheric influence from 137Cs-heavily contaminated regions. A clear latitude dependence is observed in our beryllium isotope data where highest fallout is found in mid-latitudes compared to high and low latitude regions in the Northern hemisphere. This pattern reflects the general air mass circulation in the troposphere. However, stratospheric air mass influence was also identified in mainly single events and through tropopause folding during spring-summer seasons. The ratio of 10Be/7Be is used to estimate effects of air mass transport on production signal. The results show ratios between 1 and 3, much higher than the theoretically predicted value (0.6) in the atmosphere, which suggests contribution from 7Be-depleted (old) air masses. The relationship between monthly 7Be atmospheric activity and Total Fractional Cloud Cover (TFCC), collected from satellite imagery, over Sweden for the years (1991-2000) indicates a negative seasonal correlation. This observation can be related to depletion of aerosol from the atmosphere due to trapping in clouds.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 55 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 321
Earth sciences, Aerosols, Atmosphere, Cosmogenic Be-7 and Be-10, Cs-137, Clouds, Sweden, Europe, Geovetenskap
urn:nbn:se:uu:diva-7965 (URN)978-91-554-6925-2 (ISBN)
Public defence
2007-06-05, Axel Hambergsalen, Geocentrum, Villav. 16, Uppsala, 10:00
Available from: 2007-05-15 Created: 2007-05-15Bibliographically approved

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