Transitional solar dynamics, cosmic rays and global warming

📝 Abstract

Solar activity is studied using a cluster analysis of the time-fluctuations of the sunspot number. It is shown that in an Historic period the high activity components of the solar cycles exhibit strong clustering, whereas in a Modern period (last seven solar cycles: 1933-2007) they exhibit a white-noise (non-)clustering behavior. Using this observation it is shown that in the Historic period, emergence of the sunspots in the solar photosphere was strongly dominated by turbulent photospheric convection. In the Modern period, this domination was broken by a new more active dynamics of the inner layers of the convection zone. Then, it is shown that the dramatic change of the sun dynamics at the transitional period (between the Historic and Modern periods, solar cycle 1933-1944yy) had a clear detectable impact on Earth climate. A scenario of a chain of transitions in the solar convective zone is suggested in order to explain the observations, and a forecast for the global warming is suggested on the basis of this scenario. A relation between the recent transitions and solar long-period chaotic dynamics has been found. Contribution of the galactic turbulence (due to galactic cosmic rays) has been discussed. These results are also considered in a content of chaotic climate dynamics at millennial timescales.

💡 Analysis

Solar activity is studied using a cluster analysis of the time-fluctuations of the sunspot number. It is shown that in an Historic period the high activity components of the solar cycles exhibit strong clustering, whereas in a Modern period (last seven solar cycles: 1933-2007) they exhibit a white-noise (non-)clustering behavior. Using this observation it is shown that in the Historic period, emergence of the sunspots in the solar photosphere was strongly dominated by turbulent photospheric convection. In the Modern period, this domination was broken by a new more active dynamics of the inner layers of the convection zone. Then, it is shown that the dramatic change of the sun dynamics at the transitional period (between the Historic and Modern periods, solar cycle 1933-1944yy) had a clear detectable impact on Earth climate. A scenario of a chain of transitions in the solar convective zone is suggested in order to explain the observations, and a forecast for the global warming is suggested on the basis of this scenario. A relation between the recent transitions and solar long-period chaotic dynamics has been found. Contribution of the galactic turbulence (due to galactic cosmic rays) has been discussed. These results are also considered in a content of chaotic climate dynamics at millennial timescales.

📄 Content

arXiv:0805.2108v5 [astro-ph] 12 Apr 2009 Transitional solar dynamics, cosmic rays and global warming A. Bershadskii ICAR, P.O. Box 31155, Jerusalem 91000, Israel Solar activity is studied using a cluster analysis of the time-fluctuations of the sunspot number. It is shown that in an Historic period the high activity components of the solar cycles exhibit strong clustering, whereas in a Modern period (last seven solar cycles: 1933-2007) they exhibit a white-noise (non-)clustering behavior. Using this observation it is shown that in the Historic period, emergence of the sunspots in the solar photosphere was strongly dominated by turbulent photospheric convection. In the Modern period, this domination was broken by a new more active dynamics of the inner layers of the convection zone. Then, it is shown that the dramatic change of the sun dynamics at the transitional period (between the Historic and Modern periods, solar cycle 1933-1944yy) had a clear detectable impact on Earth climate. A scenario of a chain of transitions in the solar convective zone is suggested in order to explain the observations, and a forecast for the global warming is suggested on the basis of this scenario. A relation between the recent transitions and solar long-period chaotic dynamics has been found. Contribution of the galactic turbulence (due to galactic cosmic rays) has been discussed. These results are also considered in a content of chaotic climate dynamics at millennial timescales. PACS numbers: 92.70.Qr, 92.70.Mn, 96.60.qd, 98.70.Sa INTRODUCTION The sunspot number is the main direct and reliable source of information about the solar dynamics for his- toric period. This information is crucial, for instance, for analysis of a possible connection between the sun activity and the global warming. In a recent papers [1],[2] results 1800 1830 1860 1890 1920 1950 1980 2010 0 50 100 150 200 250 300 Year SSN I II III A B C -0.6 -0.4 -0.2 0 0.2 0.4 Temperature anomaly (0C) T (land and marine) FIG. 1: Sunspot number (SSN, monthly) vs time [14]. The dashed straight lines separate between periods of different in- tensity of the solar activity. The solid curve shows the global temperature anomaly (combined land and marine, 7-years running average) [20]. of a reconstruction of the sunspot number were presented for the past 11,400 years. The reconstruction shows that [1]: ”..the level of solar activity during the past 70 years is exceptional, and the previous period of equally high activity occurred more than 8,000 years ago” (section III in Fig. 1) . Figure 1 gives first indication (’by eye’), that the prominent maxima of the global temperature data (solid curve in the Fig. 1) correspond to transitions between pe- riods of different intensity of the Sun activity (character- ized by the monthly sunspot number-SSN). This observa- tion can be considered as an indication of a strong impact of the solar activity transitions on the global Earth cli- mate. Therefore, understanding of the physical processes in the Sun, which cause these activity transitions, seems to be crucial for any serious forecast for global Earth cli- mate. SUNSPOTS When magnetic field lines are twisted and poke through the solar photosphere the sunspots appear as the visible counterparts of magnetic flux tubes in the convective zone of the sun. Since a strong magnetic field is considered as a primary phenomenon that controls gen- eration of the sunspots the crucial question is: Where has the magnetic field itself been generated? The location of the solar dynamos is the subject of vigorous discussions in recent years. A general consensus had been developed to consider the shear layer at the bottom of the convec- tion zone as the main source of the solar magnetic field [3] (see, for a recent review [4]). In recent years, however, the existence of a prominent radial shear layer near the top of the convection zone has become rather obvious and the problem again became actual. The presence of large- 2 scale meandering flow fields (like jet streams), banded zonal flows and evolving meridional circulations together with intensive multiscale turbulence shows that the near surface layer is a very complex system, which can sig- nificantly affect the processes of the magnetic field and the sunspots generation. There could be two sources for the poloidal magnetic field: one near the bottom of the convection zone (or just below it [3]), another resulting from an active-region tilt near the surface of the convec- tion zone. For the recently renewed Babcock-Leighton [5],[6] solar dynamo scenario, for instance, a combina- tion of the sources was assumed for predicting future so- lar activity levels [7], [8]. In this scenario the surface generated poloidal magnetic field is carried to the bot- tom of the convection zone by turbulent diffusion or by the meridional circulation. The toroidal magnetic field is produced from this poloidal field by differential rotation in the bottom shear layer. Destabilization and e

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