HR: 0830h
AN: SH21B-0111    [PDF]
TI: Variation of Solar Activity during the Spoerer Minimum
AU: * Miyahara, H
EM: miyahara@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku,, Nagoya, 464-8601 Japan
AU: Masuda, K
EM: kmasuda@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku,, Nagoya, 464-8601 Japan
AU: Muraki, Y
EM: muraki@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku,, Nagoya, 464-8601 Japan
AU: Kataoka, R
EM: ryuho@pat.geophys.tohoku.ac.jp
AF: Planetary Atmosphere Physics Laboratory Department of Geophysics, Tohoku University, Sendai, Miyagi, 980-8578 Japan
AB: The radiocarbon content of tree rings gives information on the level of solar activity in the past. In order to clarify the variations of solar activity during the Spoerer Minimum (1416-1534 AD), we measured the annual radiocarbon content of Japanese-cedar-tree by using an accelerator mass spectrometer. We used a time-frequency analysis to investigate the frequency modulation and the amplitude variation of the 11-year cycle of the radiocarbon content. As a result, it was revealed that the 11-year cycle was stretched by several years and the amplitude was weakened in the period 1470-1520 AD, although the 11-year cycle was not modulated significantly in the other period of the Spoerer Minimum. As is well known, the length of the 11-year cycle and the intensity of solar activity have an anti correlation. Therefore, it became clear that solar activity was strongly suppressed in this 50-year interval.
DE: 1650 Solar variability
DE: 2104 Cosmic rays
DE: 2162 Solar cycle variations (7536)
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting