Comparison of spectral characteristics of long-term and short-term changes in cosmic-ray intensity

1966 ◽  
Vol 45 (2) ◽  
pp. 132-137 ◽  
Author(s):  
R. P. Kane
Keyword(s):  
Spectral Characteristics ◽  
Cosmic Ray ◽  
Short Term ◽  
Cosmic Ray Intensity

DAILY VARIATION IN COSMIC RAY INTENSITY ON DIFFERENT GEOMAGNETIC CONDITIONS

2002 ◽  
Vol 11 (08) ◽  
pp. 1243-1253 ◽  
Author(s):  
SANTOSH KUMAR ◽  
REKHA AGARWAL ◽  
RAJESH MISHRA ◽  
S. K. DUBEY
Keyword(s):  
Daily Variation ◽  
Cosmic Ray ◽  
Short Term ◽  
Cosmic Ray Intensity ◽  
Diurnal Anisotropy ◽  
Different Types ◽  
Term Basis ◽  
Ap Index ◽  
Selection Of

A new concept of data analysis has been attempted for studying the long/short term daily variations in cosmic ray (CR) intensity recorded with neutron monitors/meson telescopes. Fourier Technique has been applied on four different types of groups of days chosen according to their different geomagnetic conditions. The selected groups are 60 quietest days (60 QD), 120 quiet days (120 QD), continuous quiet days (CQD) and All Days (AD) in a year. CQD is a new set of days selected on the basis of Ap and Kp values. These are the days when transient magnetic variations are supposed to be regular and smooth continuously for a span of at least three days. The criteria of selection of CQD is based upon the mathematical manipulation with Ap index. The data of Deep River neutron monitoring station is used for the period 1985–1995, to investigate for a com-parative study of diurnal anisotropy in CR intensity on 60 QD, 120 QD, CQD and AD. It is observed that 60 QD are most suitable for the anisotropic studies on short/long term basis. The time/spatial variations in the amplitude and phase of the diurnal anisotropy become more pronounced for 60 QD for the period under investigation.

A study of the long-term modulation of galactic cosmic ray intensity

1970 ◽  
Vol 18 (1) ◽  
pp. 81-94 ◽  
Author(s):  
P.N. Pathak ◽  
Vikram Sarabhai
Keyword(s):  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Galactic Cosmic Ray

STUDY OF FORBUSH DECREASE EVENT AND ASSOCIATED GEOMAGNETIC FIELD AND COSMIC RAY INTENSITY VARIATION

2005 ◽  
Vol 20 (29) ◽  
pp. 6717-6719 ◽  
Author(s):  
S. K. MISHRA ◽  
D. P. TIWARI ◽  
S. C. KAUSHIK
Keyword(s):  
Forbush Decrease ◽  
Intensity Variation ◽  
Cosmic Ray ◽  
Strong Relationship ◽  
Geomagnetic Disturbances ◽  
Slow Recovery ◽  
Short Term ◽  
Cosmic Ray Intensity ◽  
Transient Disturbances ◽  
Term Basis

Transient decrease in cosmic ray intensity following by a slow recovery typically lasting for several days is identified as Forbush decrease (Fd) event. As a result the geomagnetic index (Dst) decreased up to 300 nT, indicating a large geomagnetic storm and the percentage Fd decrease has gone to 16% giving rise a cosmic ray storm. Both events coincided with interplanetary conditions. Therefore, a systematic study has been performed to investigate the variation of cosmic ray intensity along with the interplanetary and geomagnetic disturbances. Results indicate a strong relationship between geomagnetic activity and Forbush decrease on short-term basis. Two types of interplanetary transient disturbances, namely magnetic cloud events and bidirectional events are analyzed to study the short-term changes in the solar wind (SW) plasma components as well as in cosmic ray intensity.

Time variations of directional cosmic ray intensity at low latitudes: I. Comparison of daily variation of the intensity of cosmic rays incident from east and west

1961 ◽  
Vol 263 (1312) ◽  
pp. 101-117 ◽  
Keyword(s):  
Geomagnetic Field ◽  
Daily Variation ◽  
Cosmic Ray ◽  
Local Source ◽  
Cosmic Ray Intensity ◽  
Low Latitudes ◽  
Long Term Changes ◽  
Time Variations ◽  
East And West

A study has been, conducted at Ahmedabad during 1957 and 1958 of the time variations of meson intensity incident from east and west at 45° to the vertical. A characteristic differ­ence of about 6 h in the diurnal time of maximum for the east and west directions is observed to occur on many days and this has been interpreted as signifying an anisotropy of primary radiation caused by a source outside the influence of the geomagnetic field. However, there are many days on which the daily variation has a maximum near noon for both directions. On such days the predominant influence is that of a local source situated within the influence of the geomagnetic field. The local source is associated with geomagnetically disturbed days. Long-term changes in the daily variation are found to be similar for the east, vertical and west directions.

scholarly journals Solar activity, 27-day variation and long term modulation of cosmic ray intensity

Solar Physics ◽  
1970 ◽  
Vol 11 (1) ◽  
pp. 151-154 ◽  
Author(s):  
V. K. Balasubrahmanyan ◽  
D. Venkatesan
Keyword(s):  
Solar Activity ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity

scholarly journals Reconstructing the long-term cosmic ray intensity: linear relations do not work

2003 ◽  
Vol 21 (4) ◽  
pp. 863-867 ◽  
Author(s):  
K. Mursula ◽  
I. G. Usoskin ◽  
G. A. Kovaltsov
Keyword(s):  
Cosmic Ray ◽  
Geomagnetism And Paleomagnetism ◽  
Cosmic Ray Intensity ◽  
Linear Relations ◽  
Cosmic Ray Modulation ◽  
Interplanetary Physics ◽  
Long Time ◽  
Time Variations ◽  
Cosmic Ray Flux

Abstract. It was recently suggested (Lockwood, 2001) that the cosmic ray intensity in the neutron monitor energy range is linearly related to the coronal source flux, and can be reconstructed for the last 130 years using the long-term coronal flux estimated earlier. Moreover, Lockwood (2001) reconstructed the coronal flux for the last 500 years using a similar linear relation between the flux and the concentration of cosmogenic 10 Be isotopes in polar ice. Here we show that the applied linear relations are oversimplified and lead to unphysical results on long time scales. In particular, the cosmic ray intensity reconstructed by Lockwood (2001) for the last 130 years has a steep trend which is considerably larger than the trend estimated from observations during the last 65 years. Accordingly, the reconstructed cosmic ray intensity reaches or even exceeds the local interstellar cosmic ray flux around 1900. We argue that these unphysical results obtained when using linear relations are due to the oversimplified approach which does not take into account the complex and essentially nonlinear nature of long-term cosmic ray modulation in the heliosphere. We also compare the long-term cosmic ray intensity based on a linear treatment with the reconstruction based on a recent physical model which predicts a considerably lower cosmic ray intensity around 1900.Key words. Interplanetary physics (cosmic rays; heliopause and solar wind termination) – Geomagnetism and paleomagnetism (time variations, secular and long-term)

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