scholarly journals 36. The 27-day variation in cosmic ray intensity and in geomagnetic activity

1958 ◽  
Vol 6 ◽  
pp. 332-344 ◽  
Author(s):  
Scott E. Forbush
Keyword(s):  
Harmonic Analysis ◽  
Geomagnetic Activity ◽  
Statistical Significance ◽  
Cosmic Ray ◽  
Magnetic Activity ◽  
Effective Number ◽  
Cosmic Ray Intensity ◽  
Fourth Group ◽  
Sunspot Minimum ◽  
Recurrence Tendency

The amplitude of the average 27-day wave in cosmic ray intensity, at Huancayo, Peru, and its phase relative to that for the 27-day wave in international magnetic character figure (ICF) is determined from results of harmonic analysis of data for each of 246 intervals (or solar rotations) of 27 days. From these data, the variability of which is essential for tests of statistical significance, the amplitude of the average 27-day wave in cosmic ray intensity and its phase relative to that in geomagnetic activity is determined for each of three groups of solar rotations selected according to the average of the amplitudes of the 27-day waves in magnetic activity. A fourth group contained only 27-day intervals in which large cosmic ray decreases occurred. Relative to that in magnetic activity, the phase of the 27-day wave in cosmic ray intensity is found for the averages, to be the same for the four groups.The maxima of the average cosmic ray waves occur about 1·5 days after the minima of the corresponding waves in ICF. In general, the amplitude of the average 27-day wave in cosmic ray intensity, in the co-ordinate system in which its phase is relative to that of the 27-day wave in ICF tends to be greater for the selected groups of rotations with larger average ICF amplitudes. For most years near sunspot minimum the amplitude of the 27-day cosmic ray wave does not differ significantly from zero.Bartels found for 27-day waves in ICF the effective number of statistically independent 27-day waves for N successive solar rotations to be N/3; the number found for cosmic ray intensity is N/2. Thus, on the average the 27-day recurrence tendency is less for cosmic ray intensity than for 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 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

TRANSIENT DECREASES IN COSMIC RAY INTENSITY DURING THE PERIOD OCTOBER 1956 TO JANUARY 1958

1959 ◽  
Vol 37 (5) ◽  
pp. 569-578 ◽  
Author(s):  
A. G. Fenton ◽  
D. C. Rose ◽  
K. G. McCracken ◽  
B. G. Wilson
Keyword(s):  
Forbush Decrease ◽  
Cosmic Ray ◽  
Statistical Accuracy ◽  
Short Term ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
Controlling Mechanism ◽  
Intensity Changes ◽  
Recurrence Tendency ◽  
Cosmic Ray Flux

Recent nucleon intensity data obtained from high counting rate recorders at Ottawa and Hobart, and subsidiary stations, have been examined for evidence for the superposition of transient decreases. It is concluded that, with the statistical accuracy now available due to the high counting rates, it is possible to distinguish two types of transient decreases in the observed variations, superimposed upon the slower 11-year intensity changes. One of these is an almost symmetrical event lasting up to 2 weeks and exhibiting a recurrence tendency of about 27 days, while the other is the more abrupt Forbush decrease which recovers over a period of several days. The evidence indicates that the intensity-controlling mechanism responsible for these short-term transient changes is able to influence the cosmic ray flux at the earth independently of other events that may be in progress at the time. There is also evidence that the physical process controlling the Forbush type of decrease operates over a volume large compared with the earth because the intensity changes at places as far apart as Ottawa, Canada, and Hobart, Tasmania, show changes that are the same within the accuracy of the measurements.

scholarly journals 37. Correlation between cosmic ray intensity and geomagnetic activity

1958 ◽  
Vol 6 ◽  
pp. 345-354
Author(s):  
D. Venkatesan
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Geomagnetic Activity ◽  
Ionization Chamber ◽  
Cosmic Ray ◽  
The Sun ◽  
Cosmic Ray Intensity ◽  
Relative Decrease

The Chree method of analysis has been adopted for the analysis of the Ionization Chamber data for Huancayo, Cheltenham and Godhavn for 1946 and for the former two stations for 1945. The same procedure is adopted for the planetary index Kp also.The cosmic ray minimum (or maximum) precedes the minimum (or maximum) of Kp by about 4–5 days. It is also observed that the relative decrease in cosmic ray intensity per day, – ΔI/(I. Δt), follows the changes in Kp in a general way, and hence the electric field as would be expected from the consideration of the theory of emission of beams of particles from the sun with the associated frozen magnetic field and the electric field arising due to polarization.

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