• The Sun as a Low-Frequency Harmonic Oscillator

      Damon, Paul E.; Jirikowic, John L. (Department of Geosciences, The University of Arizona, 1992-01-01)
      Solar activity, as expressed by interplanetary solar wind magnetic field fluctuations, modulates the atmospheric production of 14C. Variations of atmospheric 14C can be precisely established from the cellulose within annual tree rings, an independently dated conservative archive of atmospheric carbon isotopes. Delta-14C time series interpretation shows that solar activity has varied with a recurrence period of 2115 +/- 15 (95% confidence) yr (Hallstattzeit) (Damon & Sonett 1991) over the past 7160 yr. From a non-stationary oscillation solar activity hypothesis, 52 possible spectral harmonics may result from this period. Damon and Sonett (1991) identify powerful harmonics such as the 211.5-yr (Suess) and the 88.1-yr (Gleissberg) cycles as independent fundamental periods. These stronger harmonics appear to modulate the 11-yr (Schwabe) sunspot cycle. Variations in the solar magnetic field, thus, may respond to longer period variations of the solar diameter envelope (Ribes et al. 1989). Such variations would affect solar radiative energy output and, consequently, change total solar irradiance (Sofia 1984).
    • Theoretical and Experimental Aspects of Solar Flares Manifestation in Radiocarbon Abundance in Tree Rings

      Kostantinov, A. N.; Levchenko, V. A.; Kocharov, G. E.; Mikheeva, I. V.; Cecchini, Stefano; Galli, Menotti; Nanni, Terresa; Povinec, Pavel; Ruggiero, Livio; Salomoni, Agostino (Department of Geosciences, The University of Arizona, 1992-01-01)
      We describe our method of determining solar cosmic-ray flux and spectrum in the past, based on the comparison of different cosmogenic isotopes. For the period, AD 1781–1950, we have detected several intervals with a high probability of powerful solar flares.
    • Variation of Radiocarbon Content in Tree Rings During the Maunder Minimum of Solar Activity

      Kocharov, G. E.; Peristykh, A. N.; Kereselidze, P. G.; Lomtatidze, Z. N.; Metskhvarishvili, R. Ya; Tagauri, Z. A.; Tsereteli, S. L.; Zhorzholiani, I. V. (Department of Geosciences, The University of Arizona, 1992-01-01)
      We present here annual data on 14C abundance in tree rings during the Maunder minimum of solar activity (AD 1645–1715). We show that the solar modulation persisted during the minimum. We also compare these data with measurements of 10Be concentration in dated polar ice cores and with records of aurorae recurrence during this time interval.