Dependence of cosmic ray intensity on variation of solar wind velocity measured by the GRAPES-3 experiment for space weather studies

2015 ◽  
Vol 91 (12) ◽  
Author(s):  
H. Kojima ◽  
H. M. Antia ◽  
S. R. Dugad ◽  
S. K. Gupta ◽  
P. Jagadeesan ◽  
...  
Keyword(s):  
Solar Wind ◽  
Wind Velocity ◽  
Space Weather ◽  
Solar Wind Velocity ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity

scholarly journals Low-Amplitude Anisotropic Wave Train Events during Passage of Interplanetary Magnetic Clouds / Mazas Amplitūdas Anizotropiju Viļņu Parādību Secība Starpplanētu Magnētisko Mākoņu Rašanās Laikā

2013 ◽  
Vol 50 (2) ◽  
pp. 68-72
Author(s):  
R. Agarwal ◽  
R.K. Mishra
Keyword(s):  
Solar Wind ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
Magnetic Cloud ◽  
Wave Train ◽  
Cosmic Ray ◽  
Magnetic Clouds ◽  
Cosmic Ray Intensity ◽  
The North ◽  
Low Amplitude

The work presents a continuation in the series related to the long-term space observations made by ground-based neutron monitoring stations. The cosmic ray intensity variation is considered as affected by interplanetary magnetic clouds during low-amplitude anisotropic wave train (LAAWT) events. It was observed that the solar wind velocity is higher than normal (> 300 km/s) while the interplanetary magnetic field (IMF) strength is lower than normal on the arrival of magnetic cloud during LAAWT events. The proton density is found to remain significantly low at high solar-wind velocity, which was expected. The north/south component of interplanetary magnetic field turns southward one day before the arrival of cloud and remains in this direction after that. The cosmic ray intensity is found to increase with the solar wind velocity. It is noteworthy that the cosmic ray intensity significantly increases before and 90 h after the arrival of such a cloud, and decreases gradually after its passage. The north/south component of IMF (Bz) is found to significantly correlate with latitude angle (Ө) and disturbance storm time index Dst, whereas the geomagnetic activity index (Ap) significantly anti-correlates with these parameters, decreasing with (Ө) and Dst increasing on the arrival of interplanetary magnetic cloud during LAAWT events.

The solar-wind modulation of cosmic-ray intensity

1968 ◽  
Vol 46 (10) ◽  
pp. S954-S958 ◽  
Author(s):  
S. R. Sreenivasan ◽  
R. H. Johnson
Keyword(s):  
Solar Wind ◽  
Cosmic Rays ◽  
Correlation Coefficient ◽  
Solar Wind Velocity ◽  
Interplanetary Space ◽  
Dominant Role ◽  
Cosmic Ray ◽  
Normal Pattern ◽  
Cosmic Ray Intensity ◽  
Common Basis

It is shown from a consideration of the diffusion of cosmic rays in interplanetary space that the convection of particles by the solar wind is an important effect and hence should be incorporated in all discussions of the propagation of cosmic rays. This provides a common basis for looking at the correlation between relative changes of solar-wind velocity and changes of cosmic-ray intensity. The correlation is shown to be negative and significant. The correlation coefficient is large for a Forbush event, indicating that convection plays a dominant role during the event as contrasted with the normal pattern of changes of cosmic-ray intensity. The 11-year variation of cosmic-ray intensities and the Forbush event receive a natural interpretation on the basis of this discussion.

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