Stochastic differences of the solar cycles according to monitoring cosmogenic radionuclides in fresh-fallen meteorites
Abstract
Cosmogenic radionuclides with different T_1/2, which are observed in meteorites, are natural detectors of cosmic rays along the meteorite orbits during ~1.5 T_1/2 of the radionuclides before the meteorite fall onto the Earth. The investigation of radionuclides with different T_1/2 in the chondrites with various dates of fall, which have various extension and inclination of orbits, provides us with such long sequences of homogeneous data on variation of the GCR intensity and integral gradients (E>100 MeV) in the 3D heliosphere [1]. The long sequences of homogeneous data on the GCR intensity in the stratosphere are used for evaluation of the gradients [2]. Nowadays, such a sequence of certain homogeneous data on the GCR intensity and gradients in the inner heliosphere covers ~5 solar cycles [3]. This smoothes, to a considerable extent, both the temporal and spatial GCR variations revealing the most important general regularities, namely: the dependence of the GCR gradients in the inner heliosphere (at 2-4 AU from the Sun) on the phase of the solar cycles and the constancy of the mechanism of the solar modulation of GCRs, at least over the last ~1 Ma. The most striking effect - which due to the monitoring became evident - is a stochastic difference of the solar cycles in addition to their determination by the solar activity. A rigorous analysis of correlations between the distribution and variations of GCRs and various indexes of the solar activity, as well as the strength of interplanetary magnetic fields and the title of the heliospheric current sheet in the three-dimensional heliosphere, have been carry out. As a whole, it testifies to the approximately positive correlations of all the parameters. However, the analysis has revealed some dependence of the depth of GCR modulation in the heliosphere on the character of the solar magnetic fields inversion during the maximum phases of the solar cycles, namely, on N-S asymmetry of emergence of active areas, on difference of their beginning and developing, on different lasting of the inversion periods, etc. For instance, a combined operation of the effects resulted in the deepest minimum of the GCR intensity in stratosphere in 1990-1991 and the highest GCR gradients for the 22nd solar cycle. Some peculiarities of the 23 and 24 solar cycles are considered due to study of radionuclides in the recently fallen Kosice and Chelyabinsk chondrites. The observed features of the GCR modulation during the last solar cycles could be conditioned by some disturbances of processes in the convective zone of the Sun at the change of the current secular cycle. [1] Lavrukhina A K and Ustinova G K 1990 Meteorites as Probes of Cosmic Ray Variations (Moscow: Nauka) [2] Stozhkov Yu I et al. 2009 Adv. Space Res. 44 1124-37 [3] Alexeev V A et al. 2013 Journal of Physics: Conf. Ser. 409 012146
- Publication:
-
40th COSPAR Scientific Assembly
- Pub Date:
- 2014
- Bibcode:
- 2014cosp...40E..64A