[A-CC33] Ice cores and paleoenvironmental modeling

[ACC33-P07] A quasi-monthly ¹⁰Be record from the 1850s to 1860s from the Greenland SE Dome II ice core: decadal and transient solar activity or meteorological seasonal variations

*Kazuho Horiuchi¹, Rin Yoshioka², Riko Yagihashi¹, Iizuka Yoshinori³, Sumito Matoba³, Kaoru Kawakami³, Sakiko Ishino⁴, Mahiro Sasage⁵, Mai Matsumoto⁵, Takeyasu Yamagata⁶, Hiroyuki Matsuzaki⁶ (1.Graduate School of Science and Technology, Hirosaki University, 2.Faculty of Science and Technology, Hirosaki University, 3.Institute of Low Temperature Science, Hokkaido University, 4.Institute of Nature and Environmental Technology, Kanazawa University, 5.Graduate School of Environmental Science, Hokkaido University, 6.Micro Analysis Laboratory, Tandem accelerator (MALT), The University of Tokyo)

Keywords:Beryllium 10, Cosmogenic nuclide, Solar activity, Carrington event

High-resolution records of cosmogenic ¹⁰Be preserved in ice cores serve not only as a valuable proxy for past solar activity, but also as a potential tracer of atmospheric transport of aerosols originating in the stratosphere. They can also serve as a probe to search for transient cosmic ray events caused by extreme solar storms. We present a quasi-monthly ¹⁰Be record from 1852 to 1869 CE from the Greenland SE Dome II ice core, drilled at the southeastern dome of Greenland (Lat.: 67.11ºN; Lon.: 36.28ºW; Elv.: 3160 m). The core has an “absolute” chronology based on the seasonality of the H₂O₂ concentration in the ice core over the last 225 years (Kawakami et al., 2023). The interval covered by the ¹⁰Be record corresponds to that between the late part of Solar Cycle 9 and the early part of Solar Cycle 11, which includes the timing of a historic solar storm, the Carrington event, which occurred in early September 1859.

The ¹⁰Be concentration varied between 0.179 × 10⁴ and 1.84 × 10⁴ atoms/g. The typical seasonal variation of the concentration, characterized by an increasing peak in early summer, is consistent with the recent (2000 to 2020 CE) seasonal variation of ¹⁰Be observed in the same core. However, in contrast to the recent variation, a seasonal peak in winter or early spring is occasionally observed in the profile. Additionally, we find no significant seasonal peak in 1960 and 1962 CE, the years of and just after the sunspot maximum of Solar Cycle 10. We also find no significant ¹⁰Be enhancement at and just after the timing of the Carrington event in both the monthly and annual resolution ¹⁰Be profiles. This fact is in good agreement with the conclusion of the earlier work based on a biannual tree-ring record of another cosmogenic nuclide, ¹⁴C (Miyake et al., 2023). Cross-correlation shows a reasonable relationship between the annual resolution records of ¹⁰Be, ¹⁴C, and sunspot numbers with an expected offset for the Schwabe (11-year) solar cycle, suggesting that all indices are faithful proxies for solar activity in the 19th century.