Abstract
Understanding the transport and deposition of the cosmogenic isotope10Be is vital for the application of the isotope data to infer past changes of solar activity, to reconstruct past Earth’s magnetic field intensity and climate change. Here, we use data of the cosmogenic isotope10Be from the Greenland ice cores, namely the NEEM and GRIP ice cores, to identify factors controlling its distribution. After removing the effects of the geomagnetic field on the cosmogenic radionuclide production rate, the results expose imprints of the 20–22 ka precession cycle on the Greenland10Be records of the last glacial period. This finding can further improve the understanding of10Be variability in ice sheets and has the prospect of providing better reconstructions of geomagnetic and solar activity based on cosmogenic radionuclide records.
Highlights
The cosmogenic radionuclides (e.g., 10Be) from different natural archives can provide important information of past changes in the solar and geomagnetic field (e.g., Muscheler et al (2005a), Muscheler et al (2007), Muscheler et al (2005b), Zheng et al (2021a)) and climate changes (e.g., Beck et al, 2018)
The results are discussed in terms of causes of changes in the 10Be signals, the reliability of the obtained correlations with orbital forcing cycles and implications for a better understanding of aerosol transport and deposition
The 10Be data used here are from the two longest Greenland 10Be records, namely from the NEEM (The North Greenland Eemian Ice Drilling; Zheng et al (2021b)) and GRIP (The Greenland Ice Core Project; Adolphi et al (2014), Muscheler et al (2004), Vonmoos et al (2006), Wagner et al (2001), Yiou et al (1997)) ice core projects (Supplementary Figure S2)
Summary
The cosmogenic radionuclides (e.g., 10Be) from different natural archives can provide important information of past changes in the solar and geomagnetic field (e.g., Muscheler et al (2005a), Muscheler et al (2007), Muscheler et al (2005b), Zheng et al (2021a)) and climate changes (e.g., Beck et al, 2018). Effects of Earth’s orbital forcing, including precession (change in the direction of the Earth’s axis with a cycle of about 19–23 ka), obliquity (the axial tilt which changes between 22.1° and 24.5°with a cycle of about 41 ka) and eccentricity (how round or elliptic the Earth’s orbit is and consists of cycles of 413, 125 and 95 ka that loosely combine into a 100°ka cycle) on the Earth’s climate have been known for a long time (Supplementary Figure S1 and details therein) These changes, which are termed as Milankovitch cycles, result in variability of the insolation (W/m2) of solar irradiance at the top of the atmosphere dependent on positions on Earth with time (Berger, 1988; Berger and Loutre, 1991). The results are discussed in terms of causes of changes in the 10Be signals, the reliability of the obtained correlations with orbital forcing cycles and implications for a better understanding of aerosol transport and deposition
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