17:15 〜 19:15
[ACC33-P07] グリーンランドSEドームアイスコアから得られた1850年代と60年代の準1か月分解能10Be記録
キーワード： ベリリウム10、宇宙線生成核種、太陽活動、キャリントンイベント
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.
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.