The Periodicity of Solar Activity Cycles

1994 ◽  
pp. 31-34
Author(s):  
Yu. S. Romanov ◽  
N. S. Zgonyaiko
Keyword(s):  
Solar Activity ◽  
Activity Cycles ◽  
Solar Activity Cycles

scholarly journals Solar spectral irradiance variability of some chromospheric emission lines through the solar activity cycles 21-23

2017 ◽  
pp. 71-86
Author(s):  
Ü.D. Göker ◽  
M.Sh. Gigolashvili ◽  
N. Kapanadze
Keyword(s):  
Solar Activity ◽  
Chemical Elements ◽  
Wave Length ◽  
Spectral Lines ◽  
Spectral Irradiance ◽  
Close Connection ◽  
Solar Chromosphere ◽  
Solar Spectral Irradiance ◽  
Activity Cycles ◽  
Solar Activity Cycles

A study of variations of solar spectral irradiance (SSI) in the wave-length ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV) spectral lines and international sunspot number (ISSN) from interactive data centers such as SME (NSSDC), UARS (GDAAC), SORCE (LISIRD) and SIDC, respectively. We reduced these data by using the MATLsoftware package. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm) spectral lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar activity cycles (SACs) 23 and 24. We also compared our results with the variations of solar activity indices obtained by the ground-based telescopes. Therefore, we found that plage regions decrease while facular areas are increasing in SAC 23. However, the decrease in plage regions is seen in small sunspot groups (SGs), contrary to this, these regions in large SGs are comparable to previous SACs or even larger as is also seen in facular areas. Nevertheless, negative correlations between ISSN and SSI data indicate that these variations are in close connection with the classes of sunspots/SGs, faculae and plage regions. Finally, we applied the time series analysis of spectral lines corresponding to the wavelengths 121.5 nm-300.5 nm and made comparisons with the ISSN data. We found an unexpected increase in the 298.5 nm line for the Fe II ion. The variability of Fe II ion 298.5 nm line is in close connection with the facular areas and plage regions, and the sizes of these solar surface indices play an important role for the SSI variability, as well. So, we compared the connection between the sizes of faculae and plage regions, sunspots/SGs, chemical elements and SSI variability. Our future work will be the theoretical study of this connection and developing of a corresponding model.

Dynamo-based scheme for forecasting the magnitude of solar activity cycles

Solar Physics ◽  
1991 ◽  
Vol 132 (1) ◽  
pp. 1-40 ◽  
Author(s):  
A. C. Layden ◽  
P. A. Fox ◽  
J. M. Howard ◽  
A. Sarajedini ◽  
K. H. Schatten ◽  
...  
Keyword(s):  
Solar Activity ◽  
Activity Cycles ◽  
Solar Activity Cycles

Characteristic Features of Solar Cosmic Rays in the 21st–24th Solar-Activity Cycles According to Data from Catalogs of Solar Proton Events

2021 ◽  
Vol 61 (1) ◽  
pp. 6-13
Author(s):  
G. A. Bazilevskaya ◽  
E. I. Daibog ◽  
Yu. I. Logachev ◽  
N. A. Vlasova ◽  
E. A. Ginzburg ◽  
...  
Keyword(s):  
Solar Activity ◽  
Cosmic Rays ◽  
Solar Proton ◽  
Solar Cosmic Rays ◽  
Activity Cycles ◽  
Solar Proton Events ◽  
Characteristic Features ◽  
Solar Activity Cycles

Stratospheric Measurements of Magnetospheric Electron Precipitation and Interplanetary Medium Conditions in Solar Activity Cycles 22–24

2018 ◽  
Vol 52 (3) ◽  
pp. 189-194
Author(s):  
G. A. Bazilevskaya ◽  
M. S. Kalinin ◽  
M. B. Krainev ◽  
V. S. Makhmutov ◽  
A. R. Novakova ◽  
...  
Keyword(s):  
Solar Activity ◽  
Interplanetary Medium ◽  
Electron Precipitation ◽  
Activity Cycles ◽  
Solar Activity Cycles

scholarly journals Global evolution of solar magnetic fields and prediction of activity cycles

2019 ◽  
Vol 15 (S354) ◽  
pp. 147-156
Author(s):  
Irina N. Kitiashvili
Keyword(s):  
Solar Activity ◽  
Magnetic Fields ◽  
Activity Cycle ◽  
Dynamo Model ◽  
Solar Magnetic Fields ◽  
Solar Cycles ◽  
Multiscale Dynamics ◽  
Activity Cycles ◽  
Solar Dynamics ◽  
Solar Activity Cycles

AbstractPrediction of solar activity cycles is challenging because physical processes inside the Sun involve a broad range of multiscale dynamics that no model can reproduce and because the available observations are highly limited and cover mostly surface layers. Helioseismology makes it possible to probe solar dynamics in the convective zone, but variations in differential rotation and meridional circulation are currently available for only two solar activity cycles. It has been demonstrated that sunspot observations, which cover over 400 years, can be used to calibrate the Parker-Kleeorin-Ruzmaikin dynamo model, and that the Ensemble Kalman Filter (EnKF) method can be used to link the modeled magnetic fields to sunspot observations and make reliable predictions of a following activity cycle. However, for more accurate predictions, it is necessary to use actual observations of the solar magnetic fields, which are available only for the last four solar cycles. In this paper I briefly discuss the influence of the limited number of available observations on the accuracy of EnKF estimates of solar cycle parameters, the criteria to evaluate the predictions, and application of synoptic magnetograms to the prediction of solar activity.

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