A study of the modulation regions causing 27-day cosmic-ray variations

1968 ◽  
Vol 46 (10) ◽  
pp. S970-S972 ◽  
Author(s):  
M. V. Alania ◽  
L. Kh. Shatashvili ◽  
L. I. Dorman
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Sunspot Number ◽  
Interplanetary Medium ◽  
Solar Wind Speed ◽  
Cosmic Ray ◽  
Effective Size ◽  
Neutron Data ◽  
Cosmic Ray Intensity ◽  
Sunspot Data

This is an attempt to determine the effective size of the interplanetary medium responsible for the 27-day variation in the cosmic-ray intensity. Neutron data from Mt. Norikura and Climax have been correlated with sunspot data for 80 solar revolutions beginning July 1957. The size of the modulating region was estimated from the lag between the sunspot number and the cosmic-ray variations, assuming the solar wind speed to be 400 km s−1, and it was found to be comparable with, or less than, the effective size of the modulating region causing the 11-year variation.

scholarly journals Responses and Periodic Variations of Cosmic Ray Intensity and Solar Wind Speed to Sunspot Numbers

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Jacob Oloketuyi ◽  
Yu Liu ◽  
Amobichukwu Chukwudi Amanambu ◽  
Mingyu Zhao
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Solar Wind Speed ◽  
Phase Relationship ◽  
Cosmic Ray ◽  
Strong Negative Correlation ◽  
Cosmic Ray Intensity ◽  
Sunspot Numbers ◽  
Daily Data ◽  
Wide Range

To investigate the periodic behaviour and relationship of sunspot numbers with cosmic ray intensity and solar wind speed, we present analysis from daily data generated from 1995 January to 2018 December. Cross-correlation and wavelet transform tools were employed to carry out the investigation. The analyses confirmed that the cosmic ray intensity correlates negatively with the sunspot numbers, exhibiting an asynchronous phase relationship with a strong negative correlation. The trend in cosmic ray intensity indicates that it undergoes the 11-year modulation that mainly depends on the solar activity in the heliosphere. On the other hand, the solar wind speed neither shows a clear phase relationship nor correlates with the sunspot numbers but shows a wide range of periodicities that could possibly be connected to the pattern of coronal hole configuration. A number of short and midterm variations were also observed from the wavelet analysis, i.e., 64–128 and 128–256 days for the cosmic ray intensity, 4–8, 32–64, 128–256, and 256–512 days for the solar wind speed, and 16–32, 32–64, 128–256, and 256–512 days for the sunspot numbers.

Galactic cosmic-ray modulation effect by solar-wind streams

1995 ◽  
Vol 73 (9-10) ◽  
pp. 642-646 ◽  
Author(s):  
M. A. El-Borie
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Cosmic Rays ◽  
Solar Wind Speed ◽  
Cosmic Ray ◽  
Diurnal Variations ◽  
Solar Cycles ◽  
Mean Values ◽  
Wind Speeds ◽  
Cosmic Ray Modulation

Data, from the worldwide network of neutron monitors, recorded at Deep River, Hermanus, Rome, Tokyo, and Huancayo, over two solar cycles (Nos. 20 and 21) are analyzed to study the long-term variations of the solar diurnal variations as they relate to solar-wind speed. The median primary rigidities of response (Rm) for these detectors cover the range 16 GV ≤ Rm ≤ 33 GV. We discuss the solar diurnal variations (amplitude and phase) of cosmic rays as a function of solar activity. The behavior of solar diurnal phases is completely different for the two epochs of high-wind speed. Data of solar-wind speed from 1966–1986 are classified according to the state of the daily mean values. Variation in the amplitudes of the diurnal variations, as functions of the median primary rigidity of cosmic rays, for the two selected periods (1973–1975 and 1979–1981) of high and low solar-wind speeds were determined at the selected stations. The rigidity dependence of the averaged solar diurnal variations of cosmic rays related to the high solar-wind speed was studied. The most sensitive rigidity of modulation is around 20 and 30 GV during the 1973–1975 and 1979–1981 periods, respectively. Our results also show that there is a significant correlation in the solar diurnal amplitudes between the two divisions of high and low solar-wind speed days.

scholarly journals Cosmic Ray Signatures of Different Types of Solar Wind Streams

1990 ◽  
Vol 142 ◽  
pp. 259-260
Author(s):  
P.K. Shrivastava ◽  
S.P. Agrawal
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Solar Wind Speed ◽  
Coronal Holes ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Wind Speeds ◽  
Different Types ◽  
Speed Solar Wind ◽  
High Speed Solar Wind

The earlier concept of average solar wind speed has changed with time. Besides quiet periods of low/average solar wind speeds, two different kinds of solar sources (solar flares and coronal holes) have been identified to produce high speed solar wind streams. In an earlier investigation, it was reported that the high speed streams associated to these sources produce distinctly different effects on the cosmic ray intensity (Venkatesan, et. al., 1982).

Effects of Different Solar Wind Speed Profiles in the Heliosheath on the Modulation of Cosmic‐Ray Protons

2006 ◽  
Vol 640 (2) ◽  
pp. 1119-1134 ◽  
Author(s):  
U. W. Langner ◽  
M. S. Potgieter ◽  
H. Fichtner ◽  
T. Borrmann
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Solar Wind Speed ◽  
Cosmic Ray
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