Periodicities in Solar Activity, Solar Radiation and Their Links with Terrestrial Environment

Solar magnetic activity is expressed via variations of sunspots and active regions varying on different timescales. The most accepted is an 11-year period supposedly induced by the electromagnetic solar dynamo mechanism. There are also some shorter or longer timescales detected: the biennial cycle (2 - 2.7 years), Gleisberg cycle (80 - 100 years), and Hallstatt’s cycle (2100 - 2300 years). Recently, using Principal Component Analysis (PCA) of the observed solar background magnetic field (SBMF), another period of 330 - 380 years, or Grand Solar Cycle (GSC), was derived from the summary curve of two eigenvectors of SBMF. In this paper, a spectral analysis of the averaged sunspot numbers, solar irradiance, and the summary curve of eigenvectors of SBMF was carried out using Morlet wavelet and Fourier transforms. We detect a 10.7-year cycle from the sunspots and modulus summary curve of eigenvectors as well a 22-year-cycle and the grand solar cycle of 342 - 350-years from the summary curve of eigenvectors. The Gleissberg centennial cycle is only detected on the full set of averaged sunspot numbers for 400 years or by adding a quadruple component to the summary curve of eigenvectors. Another period of 2200 - 2300 years is detected in the Holocene data of solar irradiance measured from the abundance of 14C isotope. This period was also confirmed with the period of about 2000 - 2100 years derived from a baseline of the solar background magnetic field, supposedly, caused by the solar inertial motion (SIM) induced by the gravitation of large planets. The implication of these findings for different deposition of solar radiation into the northern and southern hemispheres of the Earth caused by the combined effects of the solar activity and solar inertial motion on the terrestrial atmosphere is also discussed.

Terrestrial Temperature, Sea Levels and Ice Area Links with Solar Activity and Solar Orbital Motion

This paper explores the links between terrestrial temperature, sea levels and ice areas in both hemispheres with solar activity indices expressed through averaged sunspot numbers together with the summary curve of eigenvectors of the solar background magnetic field (SBMF) and with changes of Sun-Earth distances caused by solar inertial motion resulting from the gravitation of large planets in the solar system. Using the wavelet analysis of the GLB and HadCRUTS datasets two periods: 21.4 and 36 years in GLB, set and the period of about 19.6 years in the HadCRUTS are discovered. The 21.4-year period is associated with variations in solar activity defined by the summary curve of the largest eigenvectors of the SBMF. A dominant 21.4-year period is also reported in the variations of the sea level, which is linked with the period of 21.4 years detected in the GLB temperature and the summary curve of the SBMF variations. The wavelet analysis of ice and snow areas shows that in the Southern hemisphere, it does not show any links to solar activity periods while in the Northern hemisphere, the ice area reveals a period of 10.7 years equal to a usual solar activity cycle. The TSI in March-August of every year is found to grow with every year following closely the temperature curve, because the Sun moves closer to the Earth orbit owing to gravitation of large planets (solar inertial motion, SIM), while the variations of solar radiation during a whole year have more steady distribution without a sharp TSI increase during the last two centuries. The additional TSI contribution caused by SIM is likely to secure the additional energy input and exchange between the ocean and atmosphere.

Investigation of a Possible Link between Solar Activity and Climate Change in Saudi Arabia: Rainfall Patterns

In this study, annual, quarterly, and monthly mean precipitation data in Saudi Arabia were correlated with sunspot number (SSN) and galactic cosmic ray (CR) flux over 35 years (1985-2019). The results show that the strength, magnitude, proportion and statistical significance of the relationship between precipitation and the two variables varied by season and month. We find that mean annual precipitation in Saudi Arabia, from May to November, and summer and autumn are correlated with cosmic rays and inversely correlated with SSN. Correlations of varying intensities and scales were found during the remaining months and during winter and spring. The relationships between the rainfall and SSN and CR for each solar cycle were investigated and showed that for all three cycles, the annual rainfall over Saudi Arabia has a positive correlation with CR. Different results were obtained when the seasonal rainfall data correlated with the SSNs and CRs during each cycle. The results obtained, in terms of their strength and magnitude, are affected by terrestrial and extra-terrestrial factors. These factors have been briefly presented and discussed. These findings represent a step towards understanding the possible role of solar activity in climate change for future meteorological phenomenon forecasting, even if the physical mechanism is still poorly quantified.

The possible influence of solar activity on Indian summer monsoon rainfall

The Indian summer monsoon rainfall （ISMR） plays an important role in the climate system of South Asia. Recently, studies about ISMR variations have been going into more depth. In this present paper, we mainly use the Scargle periodogram and wavelet transform methods to study the periodicity of ISMR changes between 1871 and 2004 and review the possible influence of solar activity on the rainfall. Analysis results show complicated ISMR variations have periodicities with remarkable time-variable characteristics. Investigating a possible connection between the rainfall and solar variations, we believe that solar activity affects the ISMR variations to some extent.

Response of the Intensity of Subtropical High in the Northern Hemisphere to Solar Activity

Using the intensity data of each northern subtropical high measured by monthly 500 hPa height charts for the recent 38 years (1954-1991), we calculate their correlations with the monthly sunspot number and monthly solar radio flux at 10.7 cm wave length, respectively. Through strict test, we further confirm a series of high correlations. Next, using a method called the non-integer (year) wave, the significant response of each subtropical high's intensity to solar activity at its main period of 10.9-year length is found. Special attention is paid to that of the eastern Pacific high, the possible mechanism of such sensible response is also analysed.

Interdecadal and decadal variation of temperature over North Pole area and the relation with solar activity

Obvious tendency and periodicity of the air temperature can be detected over the North Pole area.They are reflected as follows： a.the air temperature at the earth surface and in the middle layer of the stratosphere tends to be increased either in winter or in summer.The air temperature has increased 1.3 °C for about 50 years at a speed about 0.025 °C/year in January,and 0.013 °C/year in July.The air temperature in the middle layer of the stratosphere （10 hPa） in January has increased 10 °C.The temperature rising speed in July is 0.14 °C/year.Generally speaking,the temperature rising speed is quicker in winter than in summer and quicker in the upper layer than at the earth surface.b.The air temperature at the top layer of the troposphere （100 hPa） over the North Pole area tends to be increased either in winter or in summer.The air temperature in January has decreased 5.0 °C for about 50 years at a temperature decreasing speed about 0.094 °C/year,and at a temperature decreasing speed about 0.032 °C/year in July.The speed of the temperature decreasing is greater in winter than in summer.c.Periodicity.The air temperature respectively at different altitudes over the North Pole possesses interdecadal variation with a period of 22 years.In July the amplitude of the variation with a period of 22 years decreases rapidly from the high altitude to the low.This means that the 22–year’s period is more obvious at the high altitude than at the low altitude.At the earth surface layer in North Pole there also is obvious decadal variation with a period of 11 years.The analysis indicates that the 22-years’ period temperature variation is associated with the periodic variation of the solar magnetic field.The 11-year period temperature variation is corresponding to 11 year’ period of the variation of the sunspot number.

Variations of the temperature and solar activity in China

In this paper we analyze daily mean, minimum, and maximum temperature data collected at 119 meteorological stations over five regions of China during the period 1951-2010. The series of minimum, maximum, and mean temperatures from each climatic region have similar signatures, but there are differences among the five regions and the countrywide average. The results indicate that the periods of faster warming were not synchronous across the regions studied： warming in northeast China and Tibet began in 1986, while in central-east, southeast, and northwest China the warming emerged in 1995. Furthermore, central-east and northwest China, and Tibet, have warmed continuously since 2000, but the temperature has decreased during this period in southeast China. We evaluated the evolution of these temperature series using a novel nonlinear filtering technique based on the concept of the lifetime of temperature curves. The decadal to secular evolution of solar activity and temperature variation had similar signatures in the northeast, southeast, and northwest re- gions and the average across the whole country, indicating that solar activity is a significant control on climate change over secular time scales in these regions. In comparison with these regions, the signatures were different in central-east China and Tibet because of regional differences （e.g., landforms and elevation） and indirect effects （e.g., cloud cover influencing the radiation balance, thereby inducing climate change）. Furthermore, the results of wavelet analysis indicated that the El Nino Southem Oscillation （ENSO） has had a significant impact on climate change, but at different times among the regions, and these changes were most probably induced by differing responses of the atmospheric system to solar forcing.

Magnetohydrodynamic process in solar activity

Magnetohydrodynamics is one of the major disciplines in solar physics. Vigorous magnetohydrodynamic process is taking place in the solar convection zone and atmosphere. It controls the generating and structuring of the solar mag- netic fields, causes the accumulation of magnetic non-potential energy in the solar atmosphere and triggers the explosive magnetic energy release, manifested as vi- olent solar flares and coronal mass ejections. Nowadays detailed observations in solar astrophysics from space and on the ground urge a great need for the studies of magnetohydrodynamics and plasma physics to achieve better understanding of the mechanism or mechanisms of solar activity. On the other hand, the spectac- ular solar activity always serves as a great laboratory of magnetohydrodynamics. In this article, we reviewed a few key unresolved problems in solar activity studies and discussed the relevant issues in solar magnetohydrodynamics.

Interdecadal correlation of solar activity with Tibetan Plateau snow depth and winter atmospheric circulation in East Asia

Studies on the impact of solar activity on climate system are very important in understanding global climate change. Previous studies in this field were mostly focus on temperature, wind and geopotential height. In this paper, interdecadal correlations of solar activity with Winter Snow Depth Index （WSDI） over the Tibetan Plateau, Arctic Oscillation Index （AOI） and the East Asian Winter Monsoon Index （EAWMI） are detected respectively by using Solar Radio Flux （SRF）, Total Solar Irradiance （TSI） and Solar Sunspot Number （SSN） data and statistical methods. Arctic Oscillation and East Asian winter monsoon are typical modes of the East Asian atmospheric circulation. Research results show that on inter-decadal time scale over 11-year solar cycle, the sun modulated changes of winter snow depth over the Tibetan Plateau and East Asian atmospheric circulation. At the fourth lag year, the correlation coefficient of SRF and snow depth is 0.8013 at 0.05 significance level by Monte-Carlo test method. Our study also shows that winter snow depth over the Tibetan Plateau has significant lead and lag correlations with Arctic Oscillation and the East Asian winter monsoon on long time scale. With more snow in winter, the phase of Arctic Oscillation is positive, and East Asian winter monsoon is weak, while with less snow, the parameters are reversed. An example is the winter of 2012/2013, with decreased Tibetan Plateau snow, phase of Arctic Oscillation was negative, and East Asian winter monsoon was strong.

Long-Term Visibility Trends in the Riyadh Megacity, Central Arabian Peninsula and Their Possible Link to Solar Activity

In this study, atmospheric visibility (AV) data from Riyadh, Saudi Arabia (24.91˚N, 46.41˚E, 760 m), for the period 1976-2011 were utilized to investigate the interannual, monthly, and seasonal AV variations and trends. The magnitudes of these trends were characterized and tested using mann-kendall (MK) rank statistics at different significance levels. No significant trend in AV was observed during the 36-year period. However, a significant increase in the annual mean AV by 0.24 km per year for the period between 1976 and 1999 was found. For the period 1999-2011, AV decreased significantly by 0.16 km per year. The potential effects of air temperature and relative humidity on AV were investigated. While these two variables could explain the observed trend of AV over some periods, they failed to do so for the whole study period. To search for extraterrestrial causes for long-term AV variations, correlation analyses between the time series of cosmic ray (CR) data (measured by NM and muon detector) and solar activity (represented by sunspot number) and AV were conducted and showed that these two variables are able to explain the AV variations for the whole study period. Additionally, power spectra analyses were conducted to investigate periodicities in the AV time series. Several significant periodicities, such as 9.8, 5.2, 2.2, 1.7, and 1.3 years were recognized. The obtained periodicities were similar to those reported by several investigators and found in solar, interplanetary, and CR parameters. The spectral and correlation results suggested that, with the expected effects of terrestrial and meteorological conditions on AV, long-term AV variations can also be related to the solar activity and associated CR modulations.

Rainfall and Temperature Variations over Burkina Faso: Possible Influence of Geomagnetic Activity, Solar Activity and Associated Energies from 1975 to 2020

This study investigates climatic parameters (rainfall, and temperature) over Burkina Faso and the possible role of solar activity and its induced energies. Through morphological investigations, we analyzed solar activity indices (sunspot number, IMF, PC index, Cosmic rays) over the last three solar cycles (1975-2020). Results about interplanetary heating show that joule heating is well correlated with the dynamic pressure of the solar plasma. Climate parameters (rainfall, Temperature) variabilities are modulated by disturbances in solar activity: 1) quiet solar characterized by a drop in solar plasma’s parameters is associated with important cloud cover and consequently bring important rainfall which chills terrestrial atmosphere, 2) active solar characterized by important input energy is associated with weak incident cosmic ray consequently with low cloudiness which brings warming. Thus, the possible natural link can be suggested between solar activity and climatic parameters even if it is not the only factor of global warming.

Application of the Cross Wavelet Transform to Solar Activity and Major Earthquakes Occurred in Chile

Historical earthquakes registered in Chile (from 1900 up to 2015) with epicenters located between 17?30'S and 56?0'S latitude and yearly mean total sunspot number have been considered in order to evaluate a significant linkage between them. The occurrence of strong earthquakes along Chile and the sunspots activity are analyzed to inspect possible influence of solar cycles on earthquakes. The cross wavelet transform and wavelet coherence analysis were applied for sequences of sunspots and earthquakes activity. An 8 - 12 years modulation of earthquakes activity has been identified.

Solar Activity and Climate Change Hazards

This paper discusses that the global worming caused by the green-house gases effect will be equal or less than that of the global cooling resulting from the solar activities. In this respect, we refer to the MDM （Modern Dalton Minimum） which stated that starting from 2005 to the next 40 years; the earth＇s surface temperature will become cooler than nowadays. However, the degree of cooling, previously mentioned in old Dalton Minimum （c. 210 year ago）, will be minimized by building-up of green-house gases effect during MDM period. Regarding to the periodicities of solar activities, it is clear that we have a new solar cycle of around 210 years now.

Investigation of Relation between Solar Activity and Earthquakes with Deep Learning Method

Solar activity (SA) has been hypothesized to be a trigger of earthquakes, although it is not as intuitively associated as other potential triggers such as tidal stress, rainfall, and the building of artificial water reservoirs. Here, we investigate the relation between SA and global earthquake numbers (GEN) by using a deep learning method to test the hypothesis. We use the daily data of GEN and SA (1996/01/01-2019/12/31) to construct a temporal convolution network (TCN). From the computational results, we confirm that the TCN captures the relation between SA and earthquakes with magnitudes from 4.0 to 4.9. We also find that the TCN achieves better fitting and prediction performance compared with previous work.

ENSO Index Variations and Links with Solar and Volcanic Activity

In this paper, we investigated the Oceanic Niño Index (ONI), for simplicity called in this paper an El Nino Southern Oscillation (ENSO) index in 1950-2023 by applying the wavelet spectral transform and the IBM SPSS correlations analysis. ONI follows the three months’ current measurements of the average temperature of the sea surface in the East-Central tropical part of the Pacific Ocean nearby the international line of the date change over the average sea surface temperature over the past 30 years. The ENSO index is found to have a strong (>87%) correlation with the Global Land-Ocean Temperature (GLOT). The scatter plots of the ENSO-GLOT correlation with the linear and cubic fits have shown that the ENSO index is better fit by the cubic polynomial increasing proportionally to a cubic power of the GLOT variations. The wavelet analysis allowed us to detect the two key periods in the ENSO (ONI) index: 4 - 5 years and 12 years. The smaller period of 4.5 years can be linked to the motion of tectonic plates while the larger period of 12 years is shown to have a noticeable correlation of 25% with frequencies of the underwater (submarine) volcanic eruptions in the areas with ENSO occurrences. Not withholding any local terrestrial factors considered to contribute to the ENSO occurrences, we investigated the possibility of the volcanic eruptions causing ENSO to be also induced by the tidal forces of Jupiter and Sun showing the correlation of the underwater volcanic eruption frequency with the Jupiter-Earth distances to be 12% and with the Sun-Earth distances, induced by the solar inertial motion, in January, when the Earth is turned to the Sun with the southern hemisphere where the ENSO occurs, to become 15%. Hence, the underwater volcanic eruptions induced by tidal forces of Jupiter and Sun can be the essential additional factors imposing this 12 year period of the ENSO (ONI) index variations.

Cyclicity related to solar activity in lacustrine organic-rich shales and their significance to shale-oil reservoir formation

The formation mechanism of micron-to centimeter-scale sedimentary cycles in lacustrine shales is a hot topic of research,because these small-scale sedimentary cycles significantly influence shale-oil distribution heterogeneity.High-frequency paleoenvironmental evolution is an important controlling factor for the formation of small-scale sedimentary cycles.However,the driving factors of high-frequency paleoenvironmental evolution and the formation process of sedimentary cycles under its constraint remain speculative.In this study,which focuses on lacustrine shales,we find that the alternating deposition of variable thickness of organic-rich lamina(ORL)and silty-grained felsic lamina(SSFL)form sedimentary cycles on the micron to centimeter scale in the Chang 73 sub-member of the Yanchang Formation in the Ordos Basin.Based on detailed petrographic characterization,in-situ geochemical parameter testing,and high-resolution cycle analysis,the formation process of cyclical sedimentary records and related paleoenvironmental evolution are investigated.Three solar activity cycles were identified from the shales,namely the 360–500 yr,81–110 yr,and 30–57 yr cycles(cycles I,II,and III,respectively).Highfrequency paleoenvironmental evolution caused by solar activity induced lake-level fluctuation,which further controlled silty-grained sediment deposition and organic matter preservation in deep lake areas.Cycle I controlled relatively long-term lake-level fluctuation,driving several pairs of SSFL and ORL deposition at the centimeter scale.Cycles II and III were short-term cycles and acted on the millimeter to micrometer scale,further complicating the sedimentary strata forming during the period of lake-level fall induced by cycle I.The cyclic deposition of SSFL and ORL correspond to cycle III.Lake-level fluctuation influenced by cycle II mainly caused SSFL thickness variation in each lamina couplet.During the period of lake-level rise induced by cycle I,periods of lake level rise during cycles II,and III show cyclic variation in reducibility,and are not thought to control the supply of coarse-grained sediments in to the deep lake areas.Frequent lake-level fluctuation promotes lamina couplet formation in thickly-bedded shales,which creates favorable conditions for shale-oil accumulation.Oil produced from ORL can migrate-locally into dissolved feldspar porosity in SSFL and therefore is able to accumulate in shales,which creates high potential for future oil exploration in thickly-bedded lacustrine shales.

Comparative analysis of extreme ultraviolet solar radiation proxies during minimum activity levels

Four extreme ultraviolet(EUV)solar radiation proxies(Magnesium II core-to-wing ratio(MgII),Lymanαflux(Fα),10.7-cm solar radio flux(F10.7),and sunspot number(Rz))were analyzed during the last four consecutive solar activity minima to investigate how they differ during minimum periods and how well they represent solar EUV radiation.Their variability within each minimum and between minima was compared by considering monthly means.A comparison was also made of their role in filtering the effect of solar activity from the critical frequency of the ionospheric F2 layer,foF2,which at mid to low latitudes depends mainly on EUV solar radiation.The last two solar cycles showed unusually low EUV radiation levels according to the four proxies.Regarding the connection between the EUV“true”variation and that of solar proxies,according to the foF2 filtering analysis,MgII and Fαbehaved in a more stable and suitable way,whereas Rz and F10.7 could be overestimating EUV levels during the last two minima,implying they would both underestimate the inter-minima difference of EUV when compared with the first two minima.

Correlation analysis between the occurrence of epidemic in ancient China and solar activity

As the globe has witnessed the pandemic,epidemic diseases exert a strong impact on human beings and ecosystems.Since the Sun is the primary energy source of the Earth,some scientific pioneers attempted to search for the discernible relation between solar activity and the incidence of epidemics.In this study,the periodic changes and trends of ancient Chinese epidemic data were analyzed in comparison with those of sunspot numbers,a solar activity proxy.The results show that the epidemic and solar activity changes are in good agreement to a certain extent,especially during the Gleissberg and the de Vries cycles.The wavelet coherence shows that the frequency of the epidemic data and sunspot numbers are highly associated.In addition,results from the ensemble empirical mode decomposition illustrate consistent variations in low-frequency decompositions.This study has important implications for further understanding of the potential impact of solar activity on Earth’s biosphere,the underlying mechanism of which needs further exploration.

Semiannual oscillation,annual oscillation,quasibiennial oscillation,and solar cycle variation of the OH airglow emission in the mesopause region

The vertically integrated emission rate,centroid altitude,peak emission rate,and peak height of the hydroxyl(OH)airglow were calculated from Thermosphere Ionosphere Mesosphere Energetics and Dynamics(TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)observations to study the seasonal and interannual variations in the intensity and location of the OH emission.The emission rate is inversely proportional to the height of the emission,with the semiannual oscillation dominating at low latitudes and the annual oscillation dominating at higher latitudes.The OH emission is modulated by the quasibiennial oscillation at the equator,and the quasibiennial oscillation signal is weak at other latitudes.We represented the vertical transport of atomic oxygen by using atomic oxygen concentrations obtained from a global atmospheric model,the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension simulations.Compared with the amplitudes of the migrating diurnal tide(DW1)calculated from temperature data observed by TIMED/SABER,we found that both the vertical transport of atomic oxygen and DW1 amplitudes in the equatorial region exhibit semiannual oscillation and quasibiennial oscillation,which have a strong correlation with the variations in the amplitude and phase of semiannual oscillation and quasibiennial oscillation in OH emission.It is likely that the DW1 affects the vertical transport of atomic oxygen that is involved in the reaction to produce O3,thus affecting the OH emission.We analyzed the relationship between OH emission and solar activity by using the solar radio flux at 10.7 cm as a proxy for solar activity.The results showed that the OH emission is well correlated with solar activity,and the modulation of OH emission by solar activity has a significant latitudinal variation.The small correlation between emission height and solar activity indicates that solar activity modulates OH emission mainly through chemical rather than dynamic processes.

The Dependence between Solar Flare Emergence and the Average Background Solar X-Ray Flux Emission

Solar flares, sudden bursts of intense electromagnetic radiation from the Sun, can significantly disrupt technological infrastructure, including communication and navigation satellites. To mitigate these risks, accurate forecasting of solar activity is crucial. This study investigates the potential of the Sun’s background X-ray flux as a tool for predicting solar flares. We analyzed data collected by solar telescopes and satellites between the years 2013 and 2023, focusing on the duration, frequency, and intensity of solar flares. We compared these characteristics with the background X-ray flux at the time of each flare event. Our analysis employed statistical methods to identify potential correlations between these solar phenomena. The key finding of this study reveals a significant positive correlation between solar flare activity and the Sun’s background X-ray flux. This suggests that these phenomena are interconnected within the framework of overall solar activity. We observed a clear trend: periods with increased occurrences of solar flares coincided with elevated background flux levels. This finding has the potential to improve solar activity forecasting. By monitoring background flux variations, we may be able to develop a more effective early warning system for potentially disruptive solar flares. This research contributes to a deeper understanding of the complex relationship between solar flares and the Sun’s overall radiative output. These findings indicate that lower-resolution X-ray sensors can be a valuable tool for identifying periods of increased solar activity by allowing us to monitor background flux variations. A more affordable approach to solar activity monitoring is advised.