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.
Udgivelsesdato: 2 June