scholarly journals Long-Term Cosmic Ray Variability and the CME-Index

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Helen Mavromichalaki ◽  
Evangelos Paouris
Keyword(s):  
Standard Deviation ◽  
Solar Cycle ◽  
Cosmic Ray ◽  
Heliospheric Current Sheet ◽  
Angular Width ◽  
Cosmic Ray Intensity ◽  
Cosmic Ray Modulation ◽  
Solar Cycle 23 ◽  
Solar Cycle 24 ◽  
Cycle 24

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.

scholarly journals Study of the Very Slow Speed Solar Wind Streams with Cosmic Ray Intensity and Ae Index for Solar Cycle 24 (2008-2013)

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Meena Pokharia ◽  
Lalan Prasad
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Cosmic Ray ◽  
Magnetic Activity ◽  
Slow Speed ◽  
Cosmic Ray Intensity ◽  
Ae Index ◽  
Solar Cycle 24 ◽  
Speed Solar Wind ◽  
Cycle 24

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.

scholarly journals Study of the Very Slow Speed Solar Wind Streams with Cosmic Ray Intensity and Ae Index for Solar Cycle 24 (2008-2013)

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Meena Pokharia ◽  
Lalan Prasad
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Cosmic Ray ◽  
Magnetic Activity ◽  
Slow Speed ◽  
Cosmic Ray Intensity ◽  
Ae Index ◽  
Solar Cycle 24 ◽  
Speed Solar Wind ◽  
Cycle 24

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

scholarly journals The Statistical Analysis of Characteristics of Coronal Mass Ejection During the Descending Phase of Solar Cycle 23 and 24

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Hemlata Dharmashaktu ◽  
N.K. Lohani
Keyword(s):  
Solar Cycle ◽  
Angular Width ◽  
Maximum Speed ◽  
Solar Cycles ◽  
Linear Speed ◽  
23Rd Solar Cycle ◽  
23Rd Cycle ◽  
Solar Cycle 23 ◽  
Solar Cycle 24 ◽  
Cycle 24

The characteristics of CMEs we studied are angular width, linear speed, and acceleration for all categories of CMEs such as narrow (W ≤20°), intermediate (20°< W<200°), wide (W ≥ 200°) and linear speed <500 km/s during the descending phase of solar cycle 23 and 24 and compared them. We have found that there are 1951 narrow CMEs during solar cycle 23 that is 1.9 times greater than in solar cycle 24 (1047). On the other side, the number of intermediate CMEs during solar cycle 24 (1571) is 1.14 times more than solar cycle 23 (1162). We observed no noticeable difference between the number of wide CMEs of solar cycle 23 (29) and 24 (36). The angular width of CMEs during the descending phase of solar cycle 23 and solar cycle 24, predominately distributed around 100-600. The fascinating result is that the angular width distributions for the descending phase of solar cycles are approximately identical. On comparing the results of linear speed of both solar cycle, we can say that, (i) 93.7% (1729) and 87.7% (908) of narrow CMEs, (ii) 97% (1328) and 94% (1479) of intermediate CMEs and (iii) 44% (13) and 42% (15) of wide CMEs have speed of <500 km s-1, respectively. Mostly the fractions of narrow and intermediate CMEs decline sharply at the speeds greater than 500 km s-1. The maximum speed observed during the 23rd cycle is 1994 km/s (wide CME) and the 24th cycle is 3163 km/s (wide CME) respectively. It was noticed that the speed of the 24th solar cycle CME is higher than the 23rd solar cycle CME. The major fraction of CMEs has acceleration in the range of -20 to 20 km s-2, all types of CMEs. The narrow and intermediate CMEs mostly show acceleration while wide CMEs show deceleration.

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
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
R Package ◽  
Least Square ◽  
Maximum Phase ◽  
Cosmic Ray Intensity ◽  
Solar Cycle 24 ◽  
Cycle 24

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.

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