Analysis of Solar Activities and Changes

The starting times of mass spontaneous social movements have been compared with temporal changes in solar activity (Wolf numbers) and in the Aa index of geomagnetic activity. It is shown that relatively high values of solar and, hence, geomagnetic activity are typical (on average) of a set of years when social cataclysms began. In addition, the relationship between social activity and geomagnetic activity is expressed somewhat more strongly than with solar activity. Heliogeomagnetic activity itself is not, however, the cause of social conflicts, as is evidenced by the weakness of the statistical relationship and the fact that the time intervals of an extremely large number of social conflicts (the decades of the 1800s, 1910s, and 1990s) occur during periods of a reduced mean level of solar and geomagnetic activity. From an averaged statistical model of the solar-geomagnetic influence on social activity and the current status and forecast of the 24th solar cycle, we can assume that heliogeomagnetic factors will contribute to an increased level of sociopolitical activity at least until the end of 2014 and, possibly, a little longer.

Variations in the total solar irradiance (TSI) associated with solar activity have been argued to influence the Earth's climate system, in particular when solar activity deviates from the average for a substantial period. One such example is the 17th Century Maunder Minimum during which sunspot numbers were extremely low, as Earth experienced the Little Ice Age. Estimation of the TSI during that period has relied on extrapolations of correlations with sunspot numbers or even more indirectly with modulations of galactic cosmic rays. We argue that there is a minimum state of solar magnetic activity associated with a population of relatively small magnetic bipoles which persists even when sunspots are absent, and that consequently estimates of TSI for the Little Ice Age that are based on scalings with sunspot numbers are generally too low. The minimal solar activity, which measurements show to be frequently observable between active-region decay products regardless of the phase of the sunspot cycle, was approached globally after an unusually long lull in sunspot activity in 2008–2009. Therefore, the best estimate of magnetic activity, and presumably TSI, for the least-active Maunder Minimum phases appears to be provided by direct measurement in 2008–2009. The implied marginally significant decrease in TSI during the least active phases of the Maunder Minimum by 140 to 360 ppm relative to 1996 suggests that drivers other than TSI dominate Earth's long-term climate change.

The solar activity by wavelet-based multifractal analysis

Evidence of solar signals in tree rings of Smith fir from Sygera Mountain in southeast Tibet

Solar variability manifestations in weather and climate characteristics

We propose using multiple regression to create a statistical model for describing climate change under the influence of specified climate-forming factors. This model provides not only estimates of the temporal evolution of global temperature, but also a set of corresponding confidence intervals with a high level of statistical significance (probability). Eliminating the linear trend of climatic temperature series (CRUTEM) and atmospheric CO2 concentration allows an objective quantitative assessment of the impact of natural factors on climate change. The global CRUTEM temperature responds quasi-synchronously to the fluctuations in the average surface temperature of the North Atlantic (AMO index); however, to changes in solar activity (Wolf numbers), it does so with a delay of approximately 15 years. The linear trend of increasing CO2 concentration in the atmosphere explains almost all the interannual variability and reflects the linear trend of global temperature, but covers only part of its interannual variability.

\n Aims. The study aims to find a relationship between the rotation of the small bright coronal structures (SBCS) described by the solar rotation parameters and indices of solar activity on monthly and yearly temporal scales.\n Methods. We analyse precise measurements of the solar differential rotation determined by tracing SBCS in SOHO-EIT images and compare the derived solar rotation parameters with the status of solar activity in the period 1998 − 2006. Full-disc solar images obtained with the Extreme ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO) were used to analyse solar differential rotation determined by tracing SBCS. An automatic method to identify and track the SBCS in EIT full-disc images with a six hour cadence is applied. We performed a statistical analysis of the monthly and yearly values of solar sidereal rotation velocity parameters A and B (corresponding to the equatorial rotation velocity and the gradient of the solar differential rotation, respectively) as a function of various solar activity indices.\n Results. The dependence of the solar rotation on the phase of the solar cycle was found. It is clearly visible for the solar rotation parameter A, whilst the results are not conclusive for parameter B. The relationship between the solar rotation and activity, expressed by the monthly relative sunspot number, the smoothed monthly relative sunspot number, the yearly relative sunspot number, and the interdiurnal variability (IDV) index was investigated. The statistically significant correlation was found for the solar rotation parameter A, whilst a very low and insignificant correlation was obtained for the rotation parameter B. \n Conclusions. During the maximum of the solar cycle 23 and just after it, the equatorial solar rotation velocity was lower than in other phases of the cycle, when there was less activity. This is consistent with other observational findings, obtained by different tracers and methods.\n

Actually, solar constant is not constant but fluctuated by ±1.5% of their average value. Solar constant indicates that the value is not constant but varies with time. Such variation is correlated with solar activity and cosmic ray. Correlation analysis shows a strong correlation between solar activity and cosmic ray and between solar activity and solar constant. Solar activity indicates by sunspot number. Correlations between solar constant variations and sunspot number variations were found to be higher than ones between variations in cosmic ray and solar constant. It was also found a positive correlation between solar constant and sunspot number, with correlation coefficient about +0.77/month and +0.95/year. In other hand, negative correlation between solar constant and cosmic ray flux i.e. −0.50/month and −0.62/year were found for monthly and yearly data respectively. A similar result was also found for the relationship between solar activity and cosmic ray flux with a negative correlation, i.e. −0.61/month and −0.69/year. When solar activities decrease, the clouds cover rate increase due to secondary ions produced by cosmic rays. The increase in the cloud cover rate causes the decrease in solar constant value and solar radiation on the earth’s surface. Solar constant plays an important role in the planning and technical analysis of equipment utilizing solar energy.

New evidence of solar variation in temperature proxies from Northern Fennoscandia

This study employs regression analysis to investigate the relationships between carbon dioxide levels, sunspot occurrences, and global temperatures, encompassing both land and sea. By uncovering these connections, the study contributes to our understanding of climate change and solar phenomena interactions. The primary objective is to reveal the intricate associations between these elements, potentially influencing climate change and solar activity. The study's outcomes have significant implications for climate change research and solar activity monitoring. The positive correlation between carbon dioxide concentration and ocean temperatures emphasizes the impact of atmospheric carbon dioxide on sea temperature fluctuations. Conversely, the inverse correlation between sunspot numbers and land/global temperatures suggests solar activity's potential role in shaping Earth's temperature oscillations. This research introduces novelty by concurrently investigating the interconnectedness of these factors. The study establishes substantial connections between carbon dioxide concentration, sunspot numbers, and global temperatures. While the models shed light on some variability, the complexity of climate change and solar activity calls for further exploration of additional factors. This underscores the need to consider multiple variables for a comprehensive understanding. Further research is recommended to enhance the precision of these models.

Solar activity changes in amplitude and long-term behavior irregularly. Fractal theory is used to examine the variation of solar activity, using daily solar indices (i.e., sunspot number, 10.7 cm radio flux, the SME Lα, Fexiv coronal emission, and the total solar irradiance measured by the ERB (Earth Radiation Budget) on the NIMBUS-7. It can handle irregular variations quantitatively. The fractal dimension of 10.7 cm radio fluxes in cycle 21 for periods of ∼ 7 days or less was 1.28, 1.3 for periods longer than ∼ 272 days, and 1.86 for periods between them, for example. Fractal dimensions for other solar indices show similar tendencies. These results suggest that solar activity varies more irregularly for time scales that are longer than several days and shorter than several months. Yearly values of fractal dimensions and bending points do not change in concert with the solar cycle.

This work examines the change in the activity of the Sun based on the reconstruction of the heliospheric modulation potential in the time interval 8000 - 1000 BC. Reconstructions of this potential were obtained using radiocarbon data, taking into account the influence of changes in the Earth’s climate. A comparison is made of the variations in the activity of the Sun with the global surface temperature. It is shown that variations in global temperature during this period could be the result of changes in solar activity. So high solar activity could lead to recorded temperature maximums around 7000 and 5300 BC. The drop in temperature in the range 3000-1000BC could be the result of low solar activity.

<p>Earth's ionosphere is formed mainly due to solar radiation, precipitating particles and cosmic rays. Its behavior is directly dependent on solar variation and the change of solar activity through out each solar cycle. The solar activity is measured by the number of sunspots and the solar radiation flux expressed by the F10.7 index. The earlier variation in electron density from solar cycle maximum to solar cycle minimum has been noted by Hargreaves (1992). He utilized the F10.7 index as a proxy for Lyman- radiation flux, which ionizes at D-region heights mainly O<sub>2</sub> and N<sub>2</sub> also NO. Utilizing the IRI model the atmospheric densities of O<sub>2</sub> and N<sub>2</sub> are assumed to be constant, NO density is the unknown. Also, it is known that the ionospheric reflection height depends on, e.g. diurnal variations [Pal & Chakrabarti, 2010] and other sudden ionospheric disturbances. Its longer term variations are not well enough studied.</p><p>Utilizing passive VLF ground based measurements with data coverage for almost the entire solar cycle 24, we compare monthly averaged solar quiet absorption curves fitted by a cosine dependence. This cosine dependence includes fixed parameters based on geography and setup of the instrument. The variables are only the solar zenith angle and the D-region absorption. This approach offers an indirect value of NO density change.</p><p>For the present study we utilize VLF monitors, which are located in northern Germany and at Czech Republic. The latter station also offers data from ionospheric sounder and continuous Doppler sounding. A simple 1-D ionospheric model is applied to compute ionospheric electron densities for daytime conditions based on solar F10.7 radiation fluxes.</p><p>The aim of this study is a comparison of solar quiet VLF curves of the solar cycle 24 maximum and minimum. Beside the change of NO density, also the variation of height of the D-region reflective layer will be discussed.</p>

The impact of asymmetrical distribution of solar activity on geomagnetic indices throughout five solar activity cycles

In a study that attempted to relate solar and human activity to Earth's recent temperature change, Connolly et al. committed a basic error in the choice of statistical methods and so overreported the effect of the Sun. A major theme of their study was that there are many data sets of past solar activity, and some of these allegedly provide statistical evidence of “most of the recent global warming being due to changes in solar activity.” We avoid methods that are known to give inaccurate results and show that for 1970–2005 Northern Hemisphere land the corrected solar attribution fraction is −7% to +5%, compared with values of up to 64% reported in Connolly et al. Their higher values are entirely due to mistaken application of statistics. Unfortunately, we cannot test truly “recent” global warming since most of their solar data sets end before 2015, and two finish in the 1990s, but all tested post-1970 periods show similarly small solar contributions. The solar-climate linkage is an area of fascinating and ongoing research with rigorous technical discussion. We argue that instead of repeating errors, they should be acknowledged and corrected so that the debate can focus on areas of legitimate scientific uncertainty.