scholarly journals Long-term observation of magnetic pulsations through the ELF Hylaty station located in the Bieszczady Mountains (south–eastern Poland)

2020 ◽  
Vol 10 ◽  
pp. 59
Author(s):  
Zenon Nieckarz ◽  
Grzegorz Michałek
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Low Frequency ◽  
Slow Solar Wind ◽  
Solar Cycles ◽  
Geomagnetic Disturbances ◽  
South Eastern ◽  
Magnetic Pulsations ◽  
Long Term Observation

Ground-based measurements of ultra- and extremely low-frequency waves (ULF/ELF) carried out in 2005–2016 (the 23rd and 24th solar cycle) at the ELF Hylaty station in Bieszczady Mountains (south–eastern Poland) were used to identify the days (360 days) in which magnetic pulsation events (MPEs) occurred. To reveal sources of MPEs at the Sun we considered their correlation with the basic indices describing solar activity. Our analysis, like earlier studies, did not reveal a significant positive correlation between the MPE detection rate and the sunspot numbers (SSN). On the other hand, we showed that MPEs are strongly correlated (correlation coefficient ≈0.70) with moderate (Dst < −70 nT) and intense (Dst < −100 nT) geomagnetic disturbances expressed by the Disturbance Storm Index (Dst). We recognized all sources of these geomagnetic storms associated with the considered MPEs. Only 44% of the MPEs were associated with storms caused by CMEs listed in the CDAW LASCO CME catalog. 56% of the MPEs were associated with storms caused by other phenomena including corotating interaction regions (CIRs), slow solar wind or CMEs not detected by LASCO. We also demonstrated that the CMEs associated with the MPEs were very energetic, i.e. they were extremely wide (partial and halo events) and fast (with the average speed above 1100 km s−1). CMEs and CIRs generally appear in different phases of solar cycles. Because MPEs are strongly related to both of these phenomena they cannot be associated with any phase of a solar cycle or with any indicator characterizing a 11-year solar activity. We also suggested that the low number of MPEs associated with CMEs is due to the anomalous 24 solar cycle. During this cycle, due to low density of the interplanetary medium, CMEs could easily eject and expand, but they were not geoeffective.

scholarly journals Prediction of Sunspot and Plage Coverage for Solar Cycle 25

2021 ◽  
Vol 922 (1) ◽  
pp. L12
Author(s):  
Valentina Penza ◽  
Francesco Berrilli ◽  
Luca Bertello ◽  
Matteo Cantoresi ◽  
Serena Criscuoli
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Empirical Relationship ◽  
Magnetic Activity ◽  
Solar Cycles ◽  
Spatial And Temporal Scales ◽  
Weather Events ◽  
Cycle 24 ◽  
Odd Cycles

Abstract Solar variability occurs over a broad range of spatial and temporal scales, from the Sun’s brightening over its lifetime to the fluctuations commonly associated with magnetic activity over minutes to years. The latter activity includes most prominently the 11 yr sunspot solar cycle and its modulations. Space weather events, in the form of solar flares, solar energetic particles, coronal mass ejections, and geomagnetic storms, have long been known to approximately follow the solar cycle occurring more frequently at solar maximum than solar minimum. These events can significantly impact our advanced technologies and critical infrastructures, making the prediction for the strength of future solar cycles particularly important. Several methods have been proposed to predict the strength of the next solar cycle, cycle 25, with results that are generally not always consistent. Most of these methods are based on the international sunspot number time series, or other indicators of solar activity. We present here a new approach that uses more than 100 yr of measured fractional areas of the visible solar disk covered by sunspots and plages and an empirical relationship for each of these two indices of solar activity in even–odd cycles. We anticipate that cycle 25 will peak in 2024 and will last for about 12 yr, slightly longer than cycle 24. We also found that, in terms of sunspot and plage areas coverage, the amplitude of cycle 25 will be substantially similar or slightly higher than cycle 24.

scholarly journals On the Prediction of Solar Cycles

Solar Physics ◽  
2021 ◽  
Vol 296 (1) ◽  
Author(s):  
V. Courtillot ◽  
F. Lopes ◽  
J. L. Le Mouël
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Transfer Function ◽  
Singular Spectrum Analysis ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Planetary Motion ◽  
Data Sets ◽  
Solar Cycles ◽  
Jovian Planets

AbstractThis article deals with the prediction of the upcoming solar activity cycle, Solar Cycle 25. We propose that astronomical ephemeris, specifically taken from the catalogs of aphelia of the four Jovian planets, could be drivers of variations in solar activity, represented by the series of sunspot numbers (SSN) from 1749 to 2020. We use singular spectrum analysis (SSA) to associate components with similar periods in the ephemeris and SSN. We determine the transfer function between the two data sets. We improve the match in successive steps: first with Jupiter only, then with the four Jovian planets and finally including commensurable periods of pairs and pairs of pairs of the Jovian planets (following Mörth and Schlamminger in Planetary Motion, Sunspots and Climate, Solar-Terrestrial Influences on Weather and Climate, 193, 1979). The transfer function can be applied to the ephemeris to predict future cycles. We test this with success using the “hindcast prediction” of Solar Cycles 21 to 24, using only data preceding these cycles, and by analyzing separately two 130 and 140 year-long halves of the original series. We conclude with a prediction of Solar Cycle 25 that can be compared to a dozen predictions by other authors: the maximum would occur in 2026.2 (± 1 yr) and reach an amplitude of 97.6 (± 7.8), similar to that of Solar Cycle 24, therefore sketching a new “Modern minimum”, following the Dalton and Gleissberg minima.

Possible Influence of the Solar Eclipse on the Global Geomagnetic Field

2017 ◽  
Vol 13 (S335) ◽  
pp. 167-170
Author(s):  
Jung-Hee Kim ◽  
Heon-Young Chang
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Solar Eclipse ◽  
Geomagnetic Field ◽  
Geomagnetic Observatory ◽  
Geomagnetic Disturbances ◽  
Solar Eclipses ◽  
A Site

AbstractWe investigate the geomagnetic field variations recorded by INTERMAGNET geomagnetic observatories. We confirm that the effect of solar eclipse can be seen over an interval of 180 minutes centered at the time of maximum eclipse on a site of a geomagnetic observatory. It is found that the effect of the solar eclipse on the geomagnetic field becomes conspicuous as the magnitude of a solar eclipse becomes larger. The effect of solar eclipses is more evident in the second half of the path of Moon’s shadow. We also find that the effect can be overwhelmed, more sensitively by geomagnetic disturbances than by solar activity of solar cycle.

ESTABLISHING SOLAR ACTIVITY TREND FOR SOLAR CYCLES 21 – 24

2021 ◽  
Vol 44 ◽  
pp. 100-106
Author(s):  
A.K. Singh ◽  
◽  
A. Bhargawa ◽  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Sunspot Number ◽  
Cosmic Ray ◽  
Occurrence Rate ◽  
The Sun ◽  
Solar Cycles ◽  
Lyman Alpha ◽  
Rate Versus ◽  
Alpha Index

Solar-terrestrial environment is manifested primarily by the physical conditions of solar interior, solar atmosphere and eruptive solar plasma. Each parameter gives unique information about the Sun and its activity according to its defined characteristics. Hence the variability of solar parameters is of interest from the point of view of plasma dynamics on the Sun and in the interplanetary space as well as for the solar-terrestrial physics. In this study, we have analysed various solar transients and parameters to establish the recent trends of solar activity during solar cycles 21, 22, 23 and 24. The correlation coefficients of linear regression of F10.7 cm index, Lyman alpha index, Mg II index, cosmic ray intensity, number of M & X class flares and coronal mass ejections (CMEs) occurrence rate versus sunspot number was examined for last four solar cycles. A running cross-correlation method has been used to study the momentary relationship among the above mentioned solar activity parameters. Solar cycle 21 witnessed the highest value of correlation for F10.7 cm index, Lyman alpha index and number of M-class and X-class flares versus sunspot number among all the considered solar cycles which were 0.979, 0.935 and 0.964 respectively. Solar cycle 22 recorded the highest correlation in case of Mg II index, Ap index and CMEs occurrence rate versus sunspot number among all the considered solar cycles (0.964, 0.384 and 0.972 respectively). Solar cycle 23 and 24 did not witness any highest correlation compared to solar cycle 21 and 22. Further the record values (highest value compared to other solar three cycles) of each solar activity parameters for each of the four solar cycles have been studied. Here solar cycle 24 has no record text at all, this simply indicating that this cycle was a weakest cycle compared to the three previous ones. We have concluded that in every domain solar 24 was weaker to its three predecessors.

scholarly journals Breathing of heliospheric structures triggered by the solar-cycle activity

2003 ◽  
Vol 21 (6) ◽  
pp. 1303-1313 ◽  
Author(s):  
K. Scherer ◽  
H. J. Fahr
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Solar Cycle ◽  
Activity Cycle ◽  
Periodic Variation ◽  
Galactic Cosmic Rays ◽  
Activity Period ◽  
Solar Cycles ◽  
Interplanetary Physics ◽  
Ram Pressure

Abstract. Solar wind ram pressure variations occuring within the solar activity cycle are communicated to the outer heliosphere as complicated time-variabilities, but repeating its typical form with the activity period of about 11 years. At outer heliospheric regions, the main surviving solar cycle feature is a periodic variation of the solar wind dynamical pressure or momentum flow, as clearly recognized by observations of the VOYAGER-1/2 space probes. This long-periodic variation of the solar wind dynamical pressure is modeled here through application of appropriately time-dependent inner boundary conditions within our multifluid code to describe the solar wind – interstellar medium interaction. As we can show, it takes several solar cycles until the heliospheric structures adapt to an average location about which they carry out a periodic breathing, however, lagged in phase with respect to the solar cycle. The dynamically active heliosphere behaves differently from a static heliosphere and especially shows a historic hysteresis in the sense that the shock structures move out to larger distances than explained by the average ram pressure. Obviously, additional energies are pumped into the heliosheath by means of density and pressure waves which are excited. These waves travel outwards through the interface from the termination shock towards the bow shock. Depending on longitude, the heliospheric sheath region memorizes 2–3 (upwind) and up to 6–7 (downwind) preceding solar activity cycles, i.e. the cycle-induced waves need corresponding travel times for the passage over the heliosheath. Within our multifluid code we also adequately describe the solar cycle variations in the energy distributions of anomalous and galactic cosmic rays, respectively. According to these results the distribution of these high energetic species cannot be correctly described on the basis of the actually prevailing solar wind conditions.Key words. Interplanetary physics (heliopause and solar wind termination; general or miscellaneous) – Space plasma physics (experimental and mathematical techniques)

scholarly journals Solar Activity and Svalbard Temperatures

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Jan-Erik Solheim ◽  
Kjell Stordahl ◽  
Ole Humlum
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Winter Temperature ◽  
Positive Trend ◽  
Seasonal Temperature ◽  
Solar Cycles ◽  
Temperature Variations ◽  
Mean Temperature ◽  
Cent Level ◽  
Cycle 24

The long temperature series at Svalbard (Longyearbyen) show large variations and a positive trend since its start in 1912. During this period solar activity has increased, as indicated by shorter solar cycles. The temperature at Svalbard is negatively correlated with the length of the solar cycle. The strongest negative correlation is found with lags 10–12 years. The relations between the length of a solar cycle and the mean temperature in the following cycle are used to model Svalbard annual mean temperature and seasonal temperature variations. Residuals from the annual and winter models show no autocorrelations on the 5 per cent level, which indicates that no additional parameters are needed to explain the temperature variations with 95 per cent significance. These models show that 60 per cent of the annual and winter temperature variations are explained by solar activity. For the spring, summer, and fall temperatures autocorrelations in the residuals exist, and additional variables may contribute to the variations. These models can be applied as forecasting models. We predict an annual mean temperature decrease for Svalbard of °C from solar cycle 23 to solar cycle 24 (2009–20) and a decrease in the winter temperature of °C.

scholarly journals Statistics of the largest geomagnetic storms per solar cycle (1844-1993)

1997 ◽  
Vol 15 (6) ◽  
pp. 719-728 ◽  
Author(s):  
D. M. Willis ◽  
P. R. Stevens ◽  
S. R. Crothers
Keyword(s):  
Statistical Analysis ◽  
Solar Cycle ◽  
Geomagnetic Storm ◽  
Extreme Values ◽  
Geomagnetic Storms ◽  
Extreme Value ◽  
Extreme Value Statistics ◽  
Relative Dispersion ◽  
Solar Cycles ◽  
Aa Index

Abstract. A previous application of extreme-value statistics to the first, second and third largest geomagnetic storms per solar cycle for nine solar cycles is extended to fourteen solar cycles (1844–1993). The intensity of a geomagnetic storm is measured by the magnitude of the daily aa index, rather than the half-daily aa index used previously. Values of the conventional aa index (1868–1993), supplemented by the Helsinki Ak index (1844–1880), provide an almost continuous, and largely homogeneous, daily measure of geomagnetic activity over an interval of 150 years. As in the earlier investigation, analytic expressions giving the probabilities of the three greatest storms (extreme values) per solar cycle, as continuous functions of storm magnitude (aa), are obtained by least-squares fitting of the observations to the appropriate theoretical extreme-value probability functions. These expressions are used to obtain the statistical characteristics of the extreme values; namely, the mode, median, mean, standard deviation and relative dispersion. Since the Ak index may not provide an entirely homogeneous extension of the aa index, the statistical analysis is performed separately for twelve solar cycles (1868–1993), as well as nine solar cycles (1868–1967). The results are utilized to determine the expected ranges of the extreme values as a function of the number of solar cycles. For fourteen solar cycles, the expected ranges of the daily aa index for the first, second and third largest geomagnetic storms per solar cycle decrease monotonically in magnitude, contrary to the situation for the half-daily aa index over nine solar cycles. The observed range of the first extreme daily aa index for fourteen solar cycles is 159–352 nT and for twelve solar cycles is 215–352 nT. In a group of 100 solar cycles the expected ranges are expanded to 137–539 and 177–511 nT, which represent increases of 108% and 144% in the respective ranges. Thus there is at least a 99% probability that the daily aa index will satisfy the condition aa < 550 for the largest geomagnetic storm in the next 100 solar cycles. The statistical analysis is used to infer that remarkable conjugate auroral observations on the night of 16 September 1770, which were recorded during the first voyage of Captain Cook to Australia, occurred during an intense geomagnetic storm.

scholarly journals On the variations of the thermospheric structure

1965 ◽  
Vol 288 (1415) ◽  
pp. 493-509 ◽  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Phase Shift ◽  
Diurnal Variation ◽  
Solar Minimum ◽  
Geomagnetic Storms ◽  
Atmospheric Temperature ◽  
Atmospheric Density ◽  
Height Range ◽  
Atmospheric Variations

The paper discusses the properties of the different effects which have been found to occur in the thermosphere and some conclusions which can be drawn with regard to the physics of the thermosphere. In the discussion of the diurnal variation the emphasis is on the behaviour of the diurnal amplitude in density during the solar cycle. At the height range between 200 and 300 km the amplitude has remarkably increased with decreasing solar activity. The relation between atmospheric density and temperature and the solar e.u.v. flux and the solar 10.7 cm flux—the latter serving as a convenient parameter—is discussed. The observational results for a phaseshift between the variations in the e.u.v. flux (or 10.7 cm flux) and the correlated variations in atmospheric temperature (or density) lie in the range between 0.5 and 2.3 days. During the solar minimum the atmospheric variations which parallel the 10.7 cm flux are far less pronounced than the variations correlated with geomagnetic activity. The phase shift derived from 45 geomagnetic storms and correlated density changes has been found to be 6 ± 3 (m.e.) h.

scholarly journals Seasonal features of geomagnetic activity: a study on the solar activity dependence

2021 ◽  
Vol 39 (5) ◽  
pp. 929-943
Author(s):  
Adriane Marques de Souza Franco ◽  
Rajkumar Hajra ◽  
Ezequiel Echer ◽  
Mauricio José Alves Bolzan
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Geomagnetic Activity ◽  
Annual Variation ◽  
Geomagnetic Storms ◽  
Solar Wind Speed ◽  
Solar Cycles ◽  
Annual Variations ◽  
Long Duration ◽  
Activity Dependence

Abstract. Seasonal features of geomagnetic activity and their solar-wind–interplanetary drivers are studied using more than five solar cycles of geomagnetic activity and solar wind observations. This study involves a total of 1296 geomagnetic storms of varying intensity identified using the Dst index from January 1963 to December 2019, a total of 75 863 substorms identified from the SuperMAG AL/SML index from January 1976 to December 2019 and a total of 145 high-intensity long-duration continuous auroral electrojet (AE) activity (HILDCAA) events identified using the AE index from January 1975 to December 2017. The occurrence rates of the substorms and geomagnetic storms, including moderate (-50nT≥Dst>-100nT) and intense (-100nT≥Dst>-250nT) storms, exhibit a significant semi-annual variation (periodicity ∼6 months), while the super storms (Dst≤-250 nT) and HILDCAAs do not exhibit any clear seasonal feature. The geomagnetic activity indices Dst and ap exhibit a semi-annual variation, while AE exhibits an annual variation (periodicity ∼1 year). The annual and semi-annual variations are attributed to the annual variation of the solar wind speed Vsw and the semi-annual variation of the coupling function VBs (where V = Vsw, and Bs is the southward component of the interplanetary magnetic field), respectively. We present a detailed analysis of the annual and semi-annual variations and their dependencies on the solar activity cycles separated as the odd, even, weak and strong solar cycles.

scholarly journals Extreme Space Weather Events during the First Cycles of Epochs with Decreased Solar Activity

2021 ◽  
Vol 61 (6) ◽  
pp. 801-809
Author(s):  
V. N. Ishkov
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Flare Activity ◽  
Solar Cycles ◽  
Geomagnetic Index ◽  
Near Earth Space ◽  
Weather Events ◽  
Solar Cyclicity ◽  
Cycle 24 ◽  
Extreme Space Weather Events

Abstract The problem of the distribution of extreme and very strong magnetic storms with intensities (G5, G4) in the first cycles (12 and 24) of epochs of lowered solar activity was considered based on homogeneous series of the geomagnetic index Aa with allowance for the modern scale of the intensity of disturbances in the near-Earth space and the scenario of solar cyclicity. The significant decrease in the number of such events and active solar phenomena in the last cycle may indicate that the sunspot and flare activity in solar cycle 12 was significantly higher than that in cycle 24, but it was significantly lower than in solar cycles of the epoch of increased solar activity.

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