The second spherical harmonic of the diurnal variation and the orientation of the interplanetary magnetic field

1968 ◽  
Vol 46 (10) ◽  
pp. S973-S975 ◽  
Author(s):  
G. V. Skeipin ◽  
P. A. Krivoshapkin ◽  
G. F. Krymsky ◽  
A. I. Kuzmin
Keyword(s):  
Magnetic Field ◽  
Diurnal Variation ◽  
Interplanetary Magnetic Field ◽  
Neutron Monitor ◽  
Spherical Harmonic ◽  
Cosmic Ray ◽  
Vector Information ◽  
Neutron Monitor Data ◽  
Distribution Vector ◽  
Monitor Data

The super neutron monitor data from Goose Bay and Deep River for 1965 have been analyzed to give month-to-month changes of the first and second harmonics of the solar-diurnal variation. Using these results together with various suppositions about the nature of the cosmic-ray distribution vector, information is obtained concerning the orientation of the interplanetary magnetic field.

Periodic cosmic-ray variations associated with the sector structure of the interplanetary magnetic field

1968 ◽  
Vol 46 (10) ◽  
pp. S966-S969 ◽  
Author(s):  
V. L. Patel ◽  
R. L. Chasson
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Neutron Monitor ◽  
Cosmic Ray ◽  
Sector Structure ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
Neutron Monitor Data ◽  
Monitor Data

Observations by IMP-1 satellite have established that the interplanetary magnetic field is divided into sectors of opposing polarity. These observations have been confirmed by observations with IMP-2 and Mariner 4. The effect of this sector structure on the cosmic-ray intensity observed on the earth has been studied using daily averages of pressure-corrected neutron monitor data from several locations. These data have been analyzed using the method of superposition of epochs, beginning at the edge of the observed sector. The results indicate periodic variations of 6–8-day periods and 0.5 to 1.0% amplitude in cosmic-ray intensity, associated with the passage of positive and negative sectors moving past the earth, including a weak recurrence at 27 days. Theoretical implications of these observations are discussed.

scholarly journals Decadal trends in the diurnal variation of galactic cosmic rays observed using neutron monitor data

2017 ◽  
Vol 35 (4) ◽  
pp. 825-838 ◽  
Author(s):  
Simon Thomas ◽  
Mathew Owens ◽  
Mike Lockwood ◽  
Chris Owen
Keyword(s):  
Phase Change ◽  
Diurnal Variation ◽  
Neutron Monitor ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Energetic Particles ◽  
Magnetic Polarity ◽  
Neutron Monitors ◽  
Neutron Monitor Data ◽  
Monitor Data

Abstract. The diurnal variation (DV) in galactic cosmic ray (GCR) flux is a widely observed phenomenon in neutron monitor data. The background variation considered primarily in this study is due to the balance between the convection of energetic particles away from the Sun and the inward diffusion of energetic particles along magnetic field lines. However, there are also times of enhanced DV following geomagnetic disturbances caused by coronal mass ejections or corotating interaction regions. In this study we investigate changes in the DV over four solar cycles using ground-based neutron monitors at different magnetic latitudes and longitudes at Earth. We divide all of the hourly neutron monitor data into magnetic polarity cycles to investigate cycle-to-cycle variations in the phase and amplitude of the DV. The results show, in general, a similarity between each of the A < 0 cycles and A > 0 cycles, but with a phase change between the two. To investigate this further, we split the neutron monitor data by solar magnetic polarity between times when the dominant polarity was either directed outward (positive) or inward (negative) at the northern solar pole. We find that the maxima and minima of the DV changes by, typically, 1–2 h between the two polarity states for all non-polar neutron monitors. This difference between cycles becomes even larger in amplitude and phase with the removal of periods with enhanced DV caused by solar wind transients. The time difference between polarity cycles is found to vary in a 22-year cycle for both the maximum and minimum times of the DV. The times of the maximum and minimum in the DV do not always vary in the same manner between A > 0 and A < 0 polarity cycles, suggesting a slight change in the anisotropy vector of GCRs arriving at Earth between polarity cycles. Polar neutron monitors show differences in phase between polarity cycles which have asymptotic directions at mid-to-high latitudes. All neutron monitors show changes in the amplitude of the DV with solar polarity, with the amplitude of the DV being a factor of 2 greater in A < 0 cycles than A > 0 cycles. In most cases the change in timing of the maximum /minimum is greatest with the stations' geomagnetic cut-off rigidity shows little variation in the DV phase with latitude. We conclude that the change in the DV with the dominant solar polar polarity is not as simple as a phase change, but rather an asymmetric variation which is sensitive to the neutron monitor's asymptotic viewing direction.

On the nature of some anomalies in the cosmic-ray distribution

1968 ◽  
Vol 46 (10) ◽  
pp. S614-S616 ◽  
Author(s):  
N. P. Chirkov ◽  
G. F. Krymsky ◽  
A. I. Kuzmin
Keyword(s):  
Magnetic Field ◽  
Diurnal Variation ◽  
Interplanetary Magnetic Field ◽  
Equatorial Plane ◽  
Geomagnetic Field ◽  
Cosmic Ray ◽  
Neutron Monitors ◽  
Vector Method ◽  
Worldwide Network ◽  
Northern And Southern Hemispheres

Diurnal and semidiurnal variations of the data from the worldwide network of neutron monitors during 1958 are analyzed using the receiving-vector method. It is shown that there exists an "antisymmetric" diurnal variation, i.e., a variation with opposite phases in the northern and southern hemispheres. After correction for the distortion due to the geomagnetic field, it is found that this variation has an amplitude of 0.03% and an hour of maximum at 21.5 hours in the northern hemisphere. If the variation is due to cosmic-ray screening in the interplanetary magnetic field, this field must have a slope of 7° with respect to the solar equatorial plane.

scholarly journals DISTURBED MAGNETOSPHERE ON NOVEMBER 7–8, 2004AND VARIATIONS OF COSMIC RAY CUTOFF RIGIDITY: LATITUDE EFFECTS

2020 ◽  
Vol 6 (3) ◽  
pp. 40-47
Author(s):  
Olga Danilova ◽  
Natalia Ptitsyna ◽  
Marta Tyasto ◽  
Valeriy Sdobnov
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Neutron Monitor ◽  
Cosmic Ray ◽  
Recovery Phase ◽  
Survey Method ◽  
Cutoff Rigidity ◽  
Strong Magnetic Storm ◽  
Current Systems ◽  
Activity Indices

We have studied the latitude behavior of cosmic ray cutoff rigidity and their sensitivity to Bz and By components of the interplanetary magnetic field and geomagnetic activity indices Dst and Kp for different phases of the November 7–8, 2004 strong magnetic storm. Cutoff rigidities have been calculated using two methods: the spectrographic global survey method in which the cutoff rigidity is determined from observational data, acquired by the neutron monitor network, and the method in which particle trajectories are calculated numerically in a model magnetic field of the magnetosphere. We have found that the sensitivity of observed cutoff rigidities to Dst changes with latitude (threshold rigidity of stations) is in antiphase with changes in the sensitivity to By. During the recovery phase of the storm, the Dst correlation with By is significantly greater than that with Bz, and the Kp correlation with Bz is greater than that with By. The By component is shown to be a predominant driver of the current systems that determine the Dst evolution during the recovery phase.

scholarly journals Cosmic ray heliospheric transport study with neutron monitor data

2015 ◽  
Vol 120 (10) ◽  
pp. 8229-8246 ◽  
Author(s):  
H. S. Ahluwalia ◽  
R. C. Ygbuhay ◽  
R. Modzelewska ◽  
L. I. Dorman ◽  
M. V. Alania
Keyword(s):  
Neutron Monitor ◽  
Cosmic Ray ◽  
Transport Study ◽  
Neutron Monitor Data ◽  
Monitor Data

The enhanced daily variation in cosmic-ray intensity

1968 ◽  
Vol 46 (10) ◽  
pp. S794-S800 ◽  
Author(s):  
D. Venkatesan ◽  
T. Mathews
Keyword(s):  
Neutron Monitor ◽  
Daily Variation ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Neutron Monitor Data ◽  
Monitor Data

The study of the super neutron monitor data from Calgary and Sulphur Mountain during January 1964 to May 1967 shows the importance of transient changes of intensity occurring over a few hours and its contribution to the daily variation. Trains of enhanced daily variation lasting a few days occur during recovery periods of fast Forbush and gradual decreases. The diurnal hour of maximum for a total of 250 days of enhanced daily variation during the period occurs at 17–18 h LT, which is the same as that for the rest of the period. The semidiurnal hour of maximum is distributed reasonably well over all hours, which points to its origin from transient changes in intensity.

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