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.

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.

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.

The Accuracy of Radiocarbon Dates

Antiquity ◽  
1963 ◽  
Vol 37 (147) ◽  
pp. 213-219 ◽  
Author(s):  
W. F. Libby
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Cosmic Ray ◽  
Average Life ◽  
Radiocarbon Dates ◽  
Cosmic Ray Intensity ◽  
Rapid Mixing ◽  
The Past ◽  
The Earth ◽  
The Magnetic Field

The first test of the accuracy of dates obtained by the radiocarbon technique was made by determining whether dates so obtained agreed with the historical dates for materials of known age (n. 1). The validity of the radiocarbon method continues to be an important question, especially in the light of the numerous results that have been accumulated and the greater precision of the technique during the past few years (n. 2).The radiocarbon content of the biosphere depends on three supposedly independent geophysical quantities: (i) the average cosmic ray intensity over a period of 8000 years (the average life of radiocarbon) as measured in our solar system but outside the earth's magnetic field (n. 1); (ii) the magnitude (but not the orientation, because of the relatively rapid mixing over the earth's surface) of the magnetic field in the vicinity of the earth, averaged over the same period (n. 1,3); and (iii) the degree of mixing of the oceans during the same period (n. 1). The question of the accuracy of radiocarbon dates therefore is of interest to geophysicists in general as well as to the archaeologists, geologists and historians who use the dates.Previous workers in this area (n. 1, 2) have reported some discrepancies, and it is the purpose here to consider the matter further.

scholarly journals Precursory signals of Forbush decreases with and without shock wave

2021 ◽  
pp. 57-63
Author(s):  
Dimitra Lingri ◽  
Helen Mavromichalaki ◽  
Anatoly V. Belov ◽  
Eugenia A. Eroshenko
Keyword(s):  
Magnetic Field ◽  
Shock Wave ◽  
Interplanetary Magnetic Field ◽  
Selection Criteria ◽  
Forbush Decrease ◽  
Cosmic Ray ◽  
Abrupt Increase ◽  
Cosmic Ray Intensity ◽  
Similarities And Differences ◽  
Solar Disturbances

Many previous studies have shown that before the beginning of a Forbush Decrease (FD) of the cosmic ray intensity, a precursor signal can be observed. All these surveys were focused on FDs that are associated with a sudden storm com- mencement (SSC). In this work we demonstrate that precursors could also be observed in events without a SSC that is determined by an abrupt increase of the interplanetary magnetic field. The type of precursory signals and their diversity among the events are the main purpose of this study. We try to figure out similarities and differences on the signals and the associated events from both categories in the last fifty years, from 1969 to 2019, using the same selection criteria of the under investigation FDs. Simultaneously the orientation of the upcoming solar disturbances in comparison to the way they configure the increase of the interplanetary magnetic field and create these signals are discussed.

scholarly journals Solar Cycle Variation of Cosmic ray Intensity along with Interplanetary and Solar Wind Plasma Parameters

2008 ◽  
Vol 45 (3) ◽  
pp. 63-68 ◽  
Author(s):  
Rajesh Mishra ◽  
Rekha Agarwal ◽  
Sharad Tiwari
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Cosmic Ray ◽  
Solar Wind Plasma ◽  
Solar Cycles ◽  
Plasma Parameters ◽  
Solar Cycle Variation ◽  
Cosmic Ray Intensity

Solar Cycle Variation of Cosmic ray Intensity along with Interplanetary and Solar Wind Plasma ParametersGalactic cosmic rays are modulated at their propagation in the heliosphere by the effect of the large-scale structure of the interplanetary medium. A comparison of the variations in the cosmic ray intensity data obtained by neutron monitoring stations with those in geomagnetic disturbance, solar wind velocity (V), interplanetary magnetic field (B), and their product (V' B) near the Earth for the period 1964-2004 has been presented so as to establish a possible correlation between them. We used the hourly averaged cosmic ray counts observed with the neutron monitor in Moscow. It is noteworthy that a significant negative correlation has been observed between the interplanetary magnetic field, product (V' B) and cosmic ray intensity during the solar cycles 21 and 22. The solar wind velocity has a good positive correlation with cosmic ray intensity during solar cycle 21, whereas it shows a weak correlation during cycles 20, 22 and 23. The interplanetary magnetic field shows a weak negative correlation with cosmic rays for solar cycle 20, and a good anti-correlation for solar cycles 21-23 with the cosmic ray intensity, which, in turn, shows a good positive correlation with disturbance time index (Dst) during solar cycles 21 and 22, and a weak correlation for cycles 20 and 23.

Changes in magnetopause positions and cosmic-ray intensity

1968 ◽  
Vol 46 (10) ◽  
pp. S1094-S1097
Author(s):  
V. L. Patel ◽  
R. L. Chasson
Keyword(s):  
Magnetic Field ◽  
Cosmic Ray ◽  
Continuous Observation ◽  
Sector Boundary ◽  
Solar Plasma ◽  
Cosmic Ray Intensity ◽  
Magnetospheric Boundary ◽  
Outward Motion ◽  
Monitor Data ◽  
Magnetic Field Experiment

Magnetic field and solar plasma experiments on satellites have shown that the position of the magnetopause (magnetospheric boundary) is variable. During a magnetic storm it may move as close as 8 geocentric earth radii. Even during quiet geomagnetic activity it may change as much as 2 earth radii. The Explorer 12 magnetic field experiment allows continuous observation of the magnetopause position twice a day for the period of August–December 1961. We have studied the changes in cosmic-ray intensity associated with such motion of the magnetopause using neutron monitor data from several ground observatories. The method of superposition of epochs shows a definite relationship, viz. inward motion of the magnetopause is associated with a decrease and outward motion with an increase in the cosmic-ray intensity. However, this relationship becomes weak after 20 days from the decrease in the magnetopause distances, i.e. increase in the energy density of the solar plasma responsible for such changes. The effect of the plasma density increase corresponds to the passage of the sector boundary of the interplanetary field.

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