Details

Autor(en) / Beteiligte

• Stuiver, Minze
• Braziunas, Thomas F

Titel

Atmospheric C-14 and century-scale solar oscillations

Ist Teil von

• Nature (London), 1989-03, Vol.338 (6214), p.405-408

Erscheinungsjahr

1989

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The solar wind plasma in interplanetary space deflects part of the Earth-bound cosmic-ray flux through its magnetic interaction with the electrically charged incoming particles. Because changes in the magnetic properties of the plasma originate at the Sun's surface, the cosmic-ray flux arriving at Earth depends upon the changing surface conditions of the Sun. Consequently, by monitoring the variable production rate of cosmogenic isotopes (such as C-14) in the atmosphere, a time history of changing conditions of the Sun's surface can be obtained. Trees, through carbon dioxide assimilation, lay down a C-14 record that provides clues toward the causes underlying C-14 production-rate changes. The authors show, from maximum-entropy spectral analysis of a 9600-yr high-precision C-14 chronology, that changes occur in the Sun's convective zone with a fundamental oscillatory mode of similar to 2.4 x 10 super(-) super(3) yr super(-) super(1) (420-yr period) and also identify several harmonics. Previous searches for cyclicity in the atmospheric C-14 record have yielded periods near 140 and 200 yr. The implications of a longer and more precise C-14 record are discussed.