Cosmic-ray intensities near the heliospheric current sheet throughout three solar activity cycles

The homogeneous series of primary cosmic ray intensity with energy > 100 MeV is obtained in the long-term balloon measurements of charged particle fluxes performed by Lebedev Physical Institute. Supplementing these data with those of neutron monitors enables us to study the cosmic ray modulation on the wide energy base during more than four solar activity cycles. In the periods of solar activity maximum a transition from cosmic ray decrease to recovery occurs. Changes in fluxes of cosmic rays of lower energy lag behind the changes in fluxes of cosmic rays of higher energy producing an energy hysteresis. After a while cosmic ray fluxes of all energies start to recover. In the cycles 20 and 22 the periods of transition from decline to recovery were shorter than in the cycles 21 and 23. This may be indicative of more complicated passage from the cosmic ray drift in the A > 0 conditions to the drift in the A < 0 conditions than vice versa.

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Solar Polar Field Reversals and Secular Variation of Cosmic Ray Intensity

Symposium - International Astronomical Union ◽

10.1017/s0074180900067395 ◽

1980 ◽

Vol 91 ◽

pp. 79-86

Author(s):

H. S. Ahluwalia

Keyword(s):

Solar Activity ◽

Cosmic Ray ◽

Activity Cycle ◽

Solar Activity Cycle ◽

Minimum Level ◽

Solar Activity Minimum ◽

Cosmic Ray Intensity ◽

Activity Cycles ◽

Solar Activity Cycles ◽

Characteristic Manner

The profile of the well-known 11-year variation of the cosmic ray intensity appears to depend upon the emerging solar polar magnetic field regime in a very characteristic manner. During the solar activity cycle 19, the cosmic ray intensity takes about seven years to recover to its solar activity minimum level. But during the solar activity cycle 20, the recovery takes place in only about two years. It appears that these characteristic recovery modes are obtainable every other solar activity cycle. We are led to suggest two model configurations for the heliosphere. We believe that an “open” heliosphere model applies to solar activity cycles 18 and 20. A “closed” heliosphere model is obtainable during solar activity cycles 17 and 19. Our results are discussed.

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Correlation of the heliospheric current sheet tilts to galactic cosmic ray modulations and solar wind speed

Astroparticle Physics ◽

10.1016/s0927-6505(98)00049-8 ◽

1999 ◽

Vol 10 (2-3) ◽

pp. 165-174 ◽

Cited By ~ 8

Author(s):

M.A. El-Borie

Keyword(s):

Solar Wind ◽

Wind Speed ◽

Current Sheet ◽

Solar Wind Speed ◽

Cosmic Ray ◽

Heliospheric Current Sheet ◽

Galactic Cosmic Ray

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

Serbian Astronomical Journal ◽

10.2298/saj160126001g ◽

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.

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