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1.
The results of an analysis of the north–south asymmetry in solar activity and solar magnetic fields are reported. The analysis is based on solar mean magnetic field and solar polar magnetic field time series, 1975–2015 (http://wso.stanford.edu), and the Greenwich sunspot data, 1875–2015 (http://solarscience.msfc.nasa.gov/greenwch.shtml). A long-term cycle (small-scale magnetic fields, toroidal component) of ~140 years is identified in the north–south asymmetry in solar activity by analyzing the cumulative sum of the time series for the north–south asymmetry in the area of sunspots. A comparative analysis of the variations in the cumulative sums of the time series composed of the daily values of the sun’s global magnetic field and in the asymmetry of the daily sunspot data over the time interval 1975–2015 shows that the photospheric large-scale magnetic fields may also have a similar long-term cycle. The variations in the asymmetry of large-scale and small-scale solar magnetic fields (sunspot area) are in sync until 2005.5 and in antiphase since then.  相似文献   

2.
The series of directly observed sunspot numbers is nearly 400 years long. We stress that the recently compiled group sunspot number series is an upgrade of the old Wolf series and should always be used before 1850. The behavior of solar activity on longer time scales can be studied only using indirect proxies. Such proxies as aurorae occurrence or naked-eye sunspot observations are qualitative indicators of solar activity but can be hardly quantitatively interpreted. Cosmogenic isotope records provide a basis for quantitative estimate of the past solar activity. Here we overview the main methods of the long-term solar activity reconstruction on the centennial to multimillennia time scale. We discuss that regression-based reconstructions of solar activity lead to very uncertain results, while recently developed physics-based models raise solar activity reconstruction to a new level and allow studying its behavior on a multimillennia time scale. In particular, the reconstructions show that the recent episode of high solar activity is quite unusual in the multimillennia time scale.  相似文献   

3.
A technique for verifying the currently available reconstructions of solar activity in the preinstrumental epoch (prior to 1615 AD), covering time intervals up to 10 000 years, has been developed and tested. The technique is based on investigation of the possibility of predicting the actual sunspot numbers determined by means of telescopic observations using reconstructed solar series. Testing several paleoreconstructions over time intervals as long as 10 000 years has shown that they most likely contain only qualitative information about the behavior of solar activity in the past and are not very suitable for extracting quantitative information. It is shown that the recently suggested hypothesis that the current level of solar activity is highest in the last 8000 years is only an arbitrary assumption that can be neither confirmed nor refuted at the present level of knowledge about the past of our star.  相似文献   

4.
In the present work an attempt has been made to investigate statistical association between solar neutrino flux data (both D2O and Salt data) collected from Sudbury Neutrino Observatory and solar irradiance data detected by Earth Radiation Budget Satellite. To serve the present purpose we have used the Multifractal Detrended Cross Correlation Analysis (MF-DCCA) based on Detrended Fluctuation Analysis (MF-X-DFA) method and the Detrending Moving Average Analysis (MF-X-DMA) which explores the long term power-law cross correlations between above two pairs of data sets. Investigation also has been made to find the frequency and time dependent local phase relationship in each pair of data sets using continuous wavelet transform (CWT) based Semblance Analysis. The Semblance Analysis reveals that there exists positive phase correlation as well as negative phase correlation between solar irradiance and D2O data at different time sub-intervals. This type of mixed phase correlation is also experienced between solar irradiance and Salt data at different time sub-intervals. The causal relationship between the D2O and the solar irradiance time series and that between Salt and solar irradiance time series have been revealed using Singular Spectral Analysis (SSA). Calculations indicate that possibly the present solar neutrino flux data (both D2O and Salt data) is supportive to predict the solar irradiance data but may not the vice versa which in turn suggests that the variability of nuclear energy generation process inside the Sun may influence the solar activity.  相似文献   

5.
Forecasting solar and geomagnetic levels of activity is essential to help plan missions and to design satellites that will survive for their useful lifetimes. Therefore, amplitudes of the upcoming solar cycles and the geomagnetic activity were forecasted using the neuro-fuzzy approach. Results of this work allow us to draw the following conclusions: Two moderate cycles are estimated to approach their maximum sunspot numbers, 110 and 116 in 2011 and 2021, respectively. However, the predicted geomagnetic activity shown to be in phase with the peak of the 24th sunspot cycle will reach its minimum three years earlier, then it will rise sharply to reach the 25th maximum a year earlier (i.e., 2020). Our analysis of the three-century long sunspot number data-set suggests that the quasi-periodic variation of the long-term evolution of solar activity could explain the irregularity of the short-term cycles seen during the past decades.  相似文献   

6.
Using two mathematical methods based on the wavelet transform and nonlinear dynamics, we reconstructed the behavior of the aa-index of geomagnetic activity in the past. Two versions of the series are provided: for the last 400 years and on an almost 1000-year time scale. We consider typical values of the aa-index at grandiose extrema of solar activity. The same high level of geomagnetic activity as that observed in the last 50 years is shown to have also taken place in the early 12th and late 14th centuries. We suggest an extended time series of A-indices of the large-scale solar magnetic field. On the 400-year time scale, we confirmed that the large-scale magnetic field develops earlier than the magnetic fields of active regions. Ohl’s prediction method was verified on the same time scale.  相似文献   

7.
The presence of a chaotic attractor is investigated in time series of 10.7 cm solar flux. The correlation dimension and the Kolomogorov entropy have been calculated for the time period 1964–1984. The values found for the Kolmogorov entropy show that chaos is indeed present. The correlation dimension found for high solar activity is 3.3 and for low solar activity is 4.5, indicating that a low-dimensionsion chaotic attractor is present in the time series analysed.  相似文献   

8.
Short-term periodicities of solar activity were studied. To perform the study, a north-south asymmetry time series was constructed by using the northern and the southern hemisphere flare index values for solar cycle 22. The statistical significance of this time series was calculated. It indicates that in most of cases the asymmetry is highly significant during cycle 22. Power spectral analysis of this time series reveals a periodicity around 25.5 days, which was announced before as a fundamental period of solar activity (Bai and Sturrock, 1991). To investigate the time agreement between the two hemispheres, the phase distribution was studied and a phase shift of about 0.5 was found. An activity trend from the north to the south was found.  相似文献   

9.
Temporal offsets between the time series of solar activity indicators provide important clues regarding the physical processes responsible for the cyclic variability in the solar atmosphere. Hysteresis patterns generated between any two indicators were popularly used to study their morphological features and further to understand their inter relationships. We use time series of different solar indicators to understand the possible cause-and-effect criteria between their respective source regions. Sensitivity of the upper atmosphere to the activity underneath might play an important role in introducing different evolutionary patterns in the profiles of solar indicators and in turn cause temporal offsets between them. Limitations in the observations may also cause relative shifts in the time series.  相似文献   

10.
We introduce the method of multiple cross-wavelet algorithm, hereafter also as Einstein’s cross functions, for the time-frequency study of solar activity records or any astronomical and geophysical time series in general. The main purpose of this algorithm is to allow the simultaneous examination of the time-frequency information contents in n > 2 time series available. Previous cross-wavelet algorithm only permit the study of two time series at a time and was not extended to the generalized n > 2 problems until now. Furthermore, our new work lifted the restriction from the original formulation that are valid only for stationary processes. We applied our new algorithm to several of the solar activity proxies available in order to demonstrate the broad and powerful utility of this technique. We have used solar activity proxy records that are obtained under different geophysical archives and time periods which are, in turn, suitable for studying both the statistical and physical properties for solar variations valid on timescales of multi-century, millennium to several millennia. We focus on documenting the methodology in this paper rather than any elaborate interpretation of the results.  相似文献   

11.
In this study, we look for the mid‐term variations in the daily average data of solar radius measurements made at the Solar Astrolabe Station of TUBITAK National Observatory (TUG) during solar cycle 23 for a time interval from 2000 February 26 to 2006 November 15. Due to the weather conditions and seasonal effect dependent on the latitude, the data series has the temporal gaps. For spectral analysis of the data series, thus, we use the Date Compensated Discrete Fourier Transform (DCDFT) and the CLEANest algorithm, which are powerful methods for irregularly spaced data. The CLEANest spectra of the solar radius data exhibit several significant mid‐term periodicities at 393.2, 338.9, 206.5, 195.2, 172.3 and 125.4 days which are consistent with periods detected in several solar time series by several authors during different solar cycles. The knowledge relating to the origin of solar radius variations is not yet present. To see whether these variations will repeat in next cycles and to understand how the amplitudes of such variations change with different phases of the solar cycles, we need more systematic efforts and the long‐term homogeneous data. Since most of the periodicities detected in the present study are frequently seen in solar activity indicators, it is thought that the physical mechanisms driving the periodicities of solar activity may also be effective in solar radius variations (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

12.
Our study deals with the correlations between the solar activity on the one hand and the solar irradiance above the Earth’s atmosphere and at ground level on the other. We analyzed the combined ACRIM I+II time series of the total solar irradiance (TSI), the Mauna Loa time series of terrestrial insolation data, and data of terrestrial cosmic ray fluxes. We find that the correlation between the TSI and the sunspot number is strongly non-linear. We interpret this as the net balance between brightening by faculae and darkening by sunspots where faculae dominate at low activity and sunspots dominate at high activity. Such a behavior is hitherto known from stellar analogs of the Sun in a statistical manner. We perform the same analysis for the Mauna Loa data of terrestrial insolation. Here we find that the linear relation between sunspot number and insolation shows more than 1% rise in insolation by sunspot number variations which is much stronger than for the TSI. Our conclusion is that the Earth atmosphere acts as an amplifier between space and ground, and that the amplification is probably controlled by solar activity. We suspect the cosmic rays intensity as the link between solar activity and atmospheric transparency. A Fourier analysis of the time series of insolation shows three dominant peaks: 10.5, 20.4, and 14.0 years. As a matter of fact, the cosmic rays data show the same pattern of significant peaks: 10.7, 22.4, and 14.9 years. This analogy supports our idea that the cosmic rays variation has influence on the transparency of the Earth atmosphere.  相似文献   

13.
Solar radio fluxes, Zurich relative sunspot number Rz, and Solar Call plage indexes daily values for the period 1957–1980 are analyzed in order to test the stability of the series with respect to time and solar activity. It is found that between the series of the 3,8 and 10 cm radio fluxes and the series of Rz no significant trend with time, solar activity or solar cycle exists when mean values for periods of the order of one year are considered.Then, the daily solar u.v.-irradiances measured since 1969 for H-Lyman-alpha and-beta, the Hel-resonance line and HeII-Lyman-alpha are compared with the 10.7 cm radio fluxes and adjusted. After adjustment, the behaviour of the four series of irradiances with respect to the 10.7 cm flux shows a similar structure as the behaviour typical for the series of the 3 cm or the 8 cm fluxes.This adjustment allows the determination of the slope of the mean variation of the u.v.-irradiances with solar activity. The increases from solar minimum to solar maximum related to the minimum values are respectively : 60% for H-Lyman-alpha, 80% for H-Lyman-beta and 90% for Hel and Hell.  相似文献   

14.
The monthly cosmic ray intensity (CRI) time series from Climax, Huancayo, Moscow, Kiel, and Calgary are used to investigate the presence of the 11-year periodic component with special attention paid to the solar influence on these variations. The results show obvious 11-year temporal characteristics in CRI variations. We also find a close anticorrelation between the 11-year solar cycle and CRI variations and time delays of the CRI relative to solar activity.  相似文献   

15.
Jakimiec  Maria  Antalová  Anna  Storini  Marisa 《Solar physics》1999,189(2):373-386
The relationship between the galactic cosmic ray modulation (CR) and the non-flare coronal level, as given by the solar soft X-ray background (XBG), is investigated from 1 July 1968 to 30 June 1980 on a daily basis. The stationarity problem of a multivariate time series, as well as the role of the short- and medium-term corona variability are faced. From them it is found that the CR/XBG relation is variable during the considered heliomagnetic semicycle, while CR and XBG are highly anticorrelated on a long-time scale (12-month averages). The CR/XBG relationship during the declining phase of solar activity shows a moderately strong anticorrelation, on short- and medium-term time scales (coefficient up to –0.77 for 27-day running averages), went towards insignificant values in the minimum phase and is only partially reconstructed during the rise of the following solar cycle. During the solar activity maximum of cycle 20 the cosmic-ray modulation is only related to the short-term coronal fluctuations (no other time scales are significant, supporting the reliability of the so-called `Gnevyshev gap' in solar parameters).  相似文献   

16.
Total solar irradiance (TSI) is the primary quantity of energy that is provided to the Earth. The properties of the TSI variability are critical for understanding the cause of the irradiation variability and its expected influence on climate variations. A deterministic property of TSI variability can provide information about future irradiation variability and expected long-term climate variation, whereas a non-deterministic variability can only explain the past.This study of solar variability is based on an analysis of two TSI data series, one since 1700 A.D. and one since 1000 A.D.; a sunspot data series since 1610 A.D.; and a solar orbit data series from 1000 A.D. The study is based on a wavelet spectrum analysis. First, the TSI data series are transformed into a wavelet spectrum. Then, the wavelet spectrum is transformed into an autocorrelation spectrum to identify stationary, subharmonic and coincidence periods in the TSI variability.The results indicate that the TSI and sunspot data series have periodic cycles that are correlated with the oscillations of the solar position relative to the barycenter of the solar system, which is controlled by gravity force variations from the large planets Jupiter, Saturn, Uranus and Neptune. A possible explanation for solar activity variations is forced oscillations between the large planets and the solar dynamo.We find that a stationary component of the solar variability is controlled by the 12-year Jupiter period and the 84-year Uranus period with subharmonics. For TSI and sunspot variations, we find stationary periods related to the 84-year Uranus period. Deterministic models based on the stationary periods confirm the results through a close relation to known long solar minima since 1000 A.D. and suggest a modern maximum period from 1940 to 2015. The model computes a new Dalton-type sunspot minimum from approximately 2025 to 2050 and a new Dalton-type period TSI minimum from approximately 2040 to 2065.  相似文献   

17.
Knowledge of the long-term variability of solar activity is of both astrophysical and geoscientific interest. Reconstructions of solar activity over multiple millennia are traditionally based on cosmogenic isotopes 14C or 10Be measured in natural terrestrial archives, but the two isotopes exhibit significant differences on millennial time scales, so that our knowledge of solar activity at this time scale remains somewhat uncertain. Here we present a new potential proxy of solar activity on the centennial-millennial time scale, based on a chemical tracer, viz. nitrate content in an ice core drilled at Talos Dome (Antarctica). We argue that this location is optimal for preserving the solar signal in the nitrate content during the Holocene. By using the firn core from the same location we show that the 11-year and Gleissberg cycles are present with the variability of 10??C?25?% in nitrate content in the pre-industrial epoch. This is consistent with the results of independent efforts of modeling HNO3 and NO y in Antarctic near surface air. However, meteorological noise on the interannual scale makes it impossible to resolve individual solar cycles. Based on different processes of formation and transport compared to cosmogenic isotopes, it provides new, independent insight into long-term solar activity and helps resolve the uncertainties related to cosmogenic isotopes as diagnostics of solar activity.  相似文献   

18.
In this paper, applying Vondrák band filter to both series of (l.o.d.) and sunspot relative number (R), we obtain variations of amplitude of 11 yr term during 1800–1985. The results show that solar cyclic signal in (l.o.d.) series is weak and unstable. The amplitude of 11 yr term in R series has long-periodic variation. The paper has briefly discussed some results about effects of solar activity on the Earth's rotation through the atmospheric motion. From the variation of (l.o.d.) obtained by band filter, we find that maxima of amplitude of annual term in (l.o.d.) occur at the same time with those of sunspot number. It implies that the angular momentum imbalance between the circulations in Southern Hemisphere and Northern Hemisphere is controlled in some way by solar activity.  相似文献   

19.
In this work we use an already-published method to infer a variation profile for the solar meridional circulation over the last 250 years. We feed this variation profile into a numerical dynamo code, and we reconstruct a sunspot time series that acts as a proxy for solar cycle activity. We perform three simulations with slightly different parameters, and the results are compared with the observational data. The medium and large correlation coefficients between reconstructed and observational time series seem to indicate that variations in meridional circulation play an important role in the modulation of solar activity.  相似文献   

20.
The Pacific Decadal Oscillation (PDO) is an El Niño-like pattern of Pacific climate variability, oscillating between its warm and cool phase about every 20–30 years as defined by oceanic temperature anomalies in the northeast and tropical Pacific Ocean. In this work, the authors investigate the possible connection between the PDO and solar activity by means of wavelet technique. The study shows obvious fluctuation characteristics in the PDO series. The modulation action from solar activity plays an important role in the oscillation of the Pacific, and there is a possible association existing in the PDO and solar activity on decade time scales.  相似文献   

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