Solar rotational period of cosmic rays and solar activity during the maximum phase of solar cycle 24

2021 ◽  
Author(s):  
Prithvi Raj Singh ◽  
A. I. Saad Farid ◽  
Y. P. Singh ◽  
A. K. Singh ◽  
Ayman A. Aly

Abstract To study the solar rotational oscillation on daily averaged time series of solar activity proxies: sunspot number (SSN), modified coronal index (MCI), solar flare index (FI), and cosmic ray intensity (CRI) are subjected to Lomb/Scargle periodogram, and continuous wavelet transform. For this purpose, we have used data of all the considered parameters from 2012 to 2015, which covers the maximum phase including the polarity reversal period of the solar cycle 24. Both spectral analysis techniques are carried out to study the behavior of 27-days on the time scale of the synodic period and to follow their evolution throughout the epoch. Further, we have used R package RobPer (least square regression) techniques and obtained a significant true period ~27 days is present in this study. It is noted that the ~27-day period of solar activity parameters and cosmic rays is much prominent during the examined period.

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Meena Pokharia ◽  
Lalan Prasad

The aim of this paper is to investigate the association of the variation of very slow speed solar wind streams (VSSSWS) with the cosmic ray intensity (CRI) and Ae index for solar cycle 24 (2008-2013). A Chree analysis by the superposed epoch method has been done in the study. The results of the present analysis showed that VSSSWS are not able to produce decreases in CRI. The prime source of the variation in magnetic activity near aurora zone is the wind interaction with the magnetosphere, but the speed of VSSSWS is low enough to produce any significant impact on aurora zone magnetic activity.


2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Meena Pokharia ◽  
Lalan Prasad

The aim of this paper is to investigate the association of the variation of very slow speed solar wind streams (VSSSWS) with the cosmic ray intensity (CRI) and Ae index for solar cycle 24 (2008-2013). A Chree analysis by the superposed epoch method has been done in the study. The results of the present analysis showed that VSSSWS are not able to produce decreases in CRI. The prime source of the variation in magnetic activity near aurora zone is the wind interaction with the magnetosphere, but the speed of VSSSWS is low enough to produce any significant impact on aurora zone magnetic activity


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Helen Mavromichalaki ◽  
Evangelos Paouris

The cosmic ray modulation in relation to solar activity indices and heliospheric parameters during the period January 1996–October 2011, covering the solar cycle 23 and the ascending phase of solar cycle 24, is studied. The new perspective of this contribution is that the CME-index, obtained from only the CMEs with angular width greater than 30 degrees, gives much better results than in previous works. The proposed model for the calculation of the modulated cosmic ray intensity obtained from the combination of solar indices and heliospheric parameters gives a very satisfactory value of the standard deviation. The best reproduction of the cosmic ray intensity is obtained by taking into account solar and interplanetary indices such as sunspot number, interplanetary magnetic field, CME-index, and heliospheric current sheet tilt. The standard deviation between the observed and calculated values is about 6.63% for the solar cycle 23 and 4.13% for the ascending part of solar cycle 24.


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