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A 600-year annual 10Be record from the NGRIP ice core, Greenland
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
(Swiss Federal Institute of Aquatic Science and Technology)
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. (Jonfysik)
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
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2009 (English)In: Geophysical Research Letters, ISSN 0094-8276, Vol. 36, L11801- p.Article in journal (Refereed) Published
Abstract [en]

Despite the extensive use of 10Be as the most significant information source on past solar activity, there has been only one record (Dye-3, Greenland) providing annual resolution over several centuries. Here we report a new annual resolution 10Be record spanning the period 1389-1994 AD, measured in an ice core from the NGRIP site in Greenland. NGRIP and Dye-3 10Be exhibits similar long-term variability, although occasional short term differences between the two sites indicate that at least two high resolution 10Be records are needed to assess local variations and to confidently reconstruct past solar activity. A comparison with sunspot and neutron records confirms that ice core 10Be reflects solar Schwabe cycle variations, and continued 10Be variability suggests cyclic solar activity throughout the Maunder and Spörer grand solar activity minima. Recent 10Be values are low; however, they do not indicate unusually high recent solar activity compared to the last 600 years.

Place, publisher, year, edition, pages
2009. Vol. 36, L11801- p.
Keyword [en]
Cryosphere: Ice cores (4932), Global Change: Solar variability (7537), Atmospheric Processes: General or miscellaneous
National Category
Earth and Related Environmental Sciences Subatomic Physics
Research subject
Earth Science with specialization in Quaternary Geology; Ion Physics
URN: urn:nbn:se:uu:diva-103019DOI: 10.1029/2009GL038004ISI: 000266741500003OAI: oai:DiVA.org:uu-103019DiVA: diva2:217216
Available from: 2009-05-13 Created: 2009-05-13 Last updated: 2011-01-25Bibliographically approved
In thesis
1. Influence of solar activity and environment on 10Be in recent natural archives
Open this publication in new window or tab >>Influence of solar activity and environment on 10Be in recent natural archives
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Understanding the link between the Sun and climate is vital in the current incidence of global climate change, and 10Be in natural archives constitutes an excellent tracer for this purpose. As cosmic rays enter the atmosphere, cosmogenic isotopes like 10Be and 14C are formed. Variations in solar activity modulate the amount of incoming cosmic rays, and thereby cosmogenic isotope production. Atmospherically produced 10Be enters natural archives such as sediments and glaciers by wet and dry deposition within about a year of production. 10Be from natural archives therefore provides information on past solar activity, and because these archives also contain climate information, solar activity and climate can be linked.

One remaining question is to what degree 10Be in natural archives reflects production, and to what extent the local and regional environment overprints the production signal. To explore this, 10Be was measured at annual resolution over the last 600 years in a Greenland ice core. Measurement potentials for these samples benefited from the development of a new laboratory method of co-precipitating 10Be with niobium. To diversify geographic location and archive media type, a pioneer study of measuring 10Be with annual resolution in varved lake sediments from Finland was conducted, with samples from the entire 20th century.

Pathways of 10Be into lake sediments are more complex than into glacial ice, inferring that contemporary atmospheric conditions may not be recorded. Here, it is shown for the first time that tracing the 11-year solar cycle through lake sediment 10Be variations is possible. Results also show that on an annual basis, 10Be deposition in ice and sediment archives is affected by local environmental conditions. On a slightly longer timescale, however, diverse 10Be records exhibit similar trends and a negative correlation with solar activity. Cyclic variability of 10Be deposition persisted throughout past grand solar minima, when little or no sunspot activity was recorded. 10Be levels indicate that although solar activity has been high during the 20th century, levels are not unprecedented in the investigated 600 years. Aerosol 10Be/7Be values indicate possible influence of stratosphere-troposphere exchange on isotope abundance and the production signal.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 64 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 654
cosmogenic isotopes, beryllium, ice cores, varved lake sediments, accelerator mass spectrometry, co-precipitation
National Category
urn:nbn:se:uu:diva-103031 (URN)978-91-554-7549-9 (ISBN)
Public defence
2009-06-11, Hambergsalen, Villavägen 16, Uppsala, 10:00 (English)
Available from: 2009-05-19 Created: 2009-05-13 Last updated: 2009-05-28Bibliographically approved

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