scholarly journals The Upper Limiting Primary Rigidity of the Cosmic Ray Solar Anisotropy

1965 ◽  
Vol 18 (5) ◽  
pp. 451 ◽  
Author(s):  
RM Jacklyn ◽  
JE Humble
Keyword(s):  
Diurnal Variation ◽  
Sea Level ◽  
Free Space ◽  
Daily Variation ◽  
Cosmic Ray ◽  
Neutron Monitors ◽  
Annual Average ◽  
Average Value

A method of determining the upper limiting rigidity of the solar diurnal variation of the cosmic ray primaries in free space is described. It involves a comparision of the response to the anisotropy of neutron monitors at sea level and of meson telescopes underground. Making use of the model for the free-space first harmonic proposed by Radio, McCracken, and Venkatesan, the annual average value for the upper limiting rigidity (Ru) in 1958 is estimated to have been 95 GV with an error of estimate of about 10-20 GV. Changes in the observed annual mean daily variation between 1958 and 1962 indicate that Ru may have decreased by about 20-40 GV over this period, but a more refined analysis is needed to confirm this.

Daily variation of cosmic rays during quiet and disturbed periods in 1965 and 1966

1968 ◽  
Vol 46 (10) ◽  
pp. S819-S822
Author(s):  
Pekka J. Tanskanen
Keyword(s):  
Daily Variation ◽  
Cosmic Ray ◽  
Ecliptic Plane ◽  
Neutron Monitors ◽  
Monthly Basis ◽  
Cosmic Ray Intensity ◽  
Variable Amplitude ◽  
Ecliptic Latitude ◽  
Streaming Velocity ◽  
Corrected Data

Data from super neutron monitors at Deep River, Churchill, Resolute, and Alert have been used to study the daily variation of cosmic-ray intensity during 1965 and 1966. Intensities have been examined on a daily, weekly, and monthly basis as a function of the asymptotic direction of vertically incident 7.5-BeV particles. The data have been analyzed in an earth-centered solar-ecliptic coordinate system in which daily (due to the earth's rotation) and seasonal (due to the inclination of the earth's axis to the ecliptic plane) variations of the asymptotic directions are considered.During undisturbed periods the daily variation has been examined by applying a digital filter to the pressure-corrected data and also to the data after subtraction of a variable-amplitude Parker–Axford theoretical diurnal variation. Particular attention has been paid to the dependence of the observed daily variation on the solar-ecliptic latitude of the asymptotic direction.Seventy-three percent of the weeks considered in 1965 and 1966 give the phase of the first harmonic in a direction 85° ± 35 °E. Sixty percent of the weekly periods show a daily variation as a function of solar-ecliptic latitude which is in agreement with the Parker–Axford "streaming-velocity" theory. During Forbush decreases the diurnal phase shifts towards earlier hours and the amplitude increases to two to three times the predecrease level.

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.

On the possibility of a two-way solar anisotropy producing the cosmic-ray diurnal variation

1968 ◽  
Vol 46 (10) ◽  
pp. S825-S827
Author(s):  
M. Kodama ◽  
K. Nagashima
Keyword(s):  
Diurnal Variation ◽  
High Altitude ◽  
Experimental Evidence ◽  
Sea Level ◽  
Phase Difference ◽  
Solar Rotation ◽  
Theoretical Calculations ◽  
Cosmic Ray ◽  
Diurnal Variations ◽  
Neutron Component

Two pieces of experimental evidence, which are inconsistent with the hypothesis of a one-way solar anisotropy as an interpretation of the cosmic-ray diurnal variation, are presented. The diurnal variation of the temperature-corrected meson component at Deep River was examined and compared with that of the neutron component. Both diurnal variations were averaged for each solar rotation from No. 1762 to No. 1787. If a one-way solar anisotropy is assumed, the time of maximum for neutrons should be about half an hour earlier than that for mesons at Deep River. However, the observations show that the phase difference between the two components is the reverse of that expected. Further evidence is obtained from a comparison of the diurnal variation on Mt. Norikura (2 770 m, 11.4 GeV) to that in Itabashi (20 m, 11.5 GeV). According to theoretical calculations based on a one-way solar anisotropy, the time of maximum at high altitude is earlier than or equal to that at sea level, but observations obtained during Dec. 1966 to Mar. 1967 suggest that the opposite is true.

Time changes of the attenuation coefficients for cosmic-ray neutron monitors

1968 ◽  
Vol 46 (10) ◽  
pp. S1041-S1043 ◽  
Author(s):  
F. Bachelet ◽  
E. Dyring ◽  
N. Iucci ◽  
G. Villoresi
Keyword(s):  
Regression Analysis ◽  
Solar Cycle ◽  
Sea Level ◽  
Time Variation ◽  
Cosmic Ray ◽  
Neutron Monitors ◽  
Attenuation Coefficients ◽  
Daily Data ◽  
Independent Estimate ◽  
Time Changes

The time variation of the attenuation coefficients is synoptically studied by regression analysis on reduced and filtered daily data of 21 IGY neutron monitors from 1957 to 1965 and 11 IQSY supermonitors from 1964 to 1966. For the sea-level IGY monitors at high latitude a typical peak-to-peak amplitude of 4% is found for the solar-cycle change, in agreement with an independent estimate of the effect. The supermonitor results show, as expected, no relevant time variation in the period studied and smaller differences than the IGY monitors among stations of similar geophysical conditions.Attenuation coefficients obtained by mobile monitor measurements in 1967 are also presented.

scholarly journals Solar Radiation Potential at Four Sites of Nepal

1970 ◽  
Vol 8 (3) ◽  
pp. 189-197 ◽  
Author(s):  
Khem N Pondyal ◽  
Binod K Bhattarai ◽  
Balkrishna Sapkota ◽  
Berit Kjeldstad
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Diurnal Variation ◽  
Sea Level ◽  
Air Pollutants ◽  
Calculated Data ◽  
Horizontal Surface ◽  
Total Solar Radiation ◽  
Annual Average ◽  
Clear Sky

The intensity of solar radiation available at the horizontal surface are measured by a CMP6 Pyranometer in Biratnagar (26.45°N, 87.27°E), Pokhara (28.22°N, 83.32°E), Kathmandu (27.72°N, 85.32°E ) and Lukla (26.69°N,86.73°E), which are 72m, 800m, 1350m, and 2850m, above from the sea level. This paper compares the seasonal and altitude variations of total solar radiation measured at above mentioned sites. The maximum total solar radiation of about 704.51 W/m2, 815.97 W/m2 777.27 W/m2 and 914.03 W/m2, are observed in Biratnagar, Pokhara, Kathmandu, and Lukla respectively. Solar radiation available in any location is affected by topography and pollution. It is found that the more solar energy is available during spring than in summer in Lukla. The solar radiation is observed higher in Pokhara than in Kathmandu. It might be due to absorption of solar energy by air pollutants which are higher in Kathmandu as compared to Pokhara.In addition we also discussed the diurnal variation of measured and calculated data of solar radiation on clear sky day. The annual average solar energy measuring 4.95, 5.44, 5.19 and 4.61 kWh/m2/day is found in Biratnagar, Pokhara Kathmandu and Lukla respectively. DOI: http://dx.doi.org/10.3126/jie.v8i3.5944 JIE 2011; 8(3): 189-197

Time and other Variations in the Intensity of Cosmic Ray Neutrons

1951 ◽  
Vol 6 (11) ◽  
pp. 592-598
Author(s):  
N. Adams ◽  
H. J. J. Braddick
Keyword(s):  
Cosmic Rays ◽  
Solar Flare ◽  
Diurnal Variation ◽  
Sea Level ◽  
Geomagnetic Latitude ◽  
Cosmic Ray ◽  
Temporal Variations ◽  
Neutron Production ◽  
Neutron Intensity

AbstractWe have measured the barometer coefficient of cosmic ray neutron production at sea level and find the value -9,25% ± 0,20/cmHg. We have shown that there is no diurnal variation of neutron production of amplitude greater than about 0,4 %. The effects of the large solar flare of November 19 th , 1949 on cosmic ray neutrons were much greater than on ionising cosmic rays at sea level; the maximum factor of increase was more than 5 and the intensity remained measurably above normal for about 12 hours. A small increase of neutron intensity is found, statistically, to be correlated with a number of recorded radio fade-outs. It is suggested that neutron measurements are particularly suitable for studying temporal variations of cosmic rays. The latitude increase of cosmic ray neutrons between geomagnetic latitude 54,5° and 56,5° was found to be about 2%. No certain increase was found between 56,5° and 59,5°.

scholarly journals A Study on Diurnal Variation of Cosmic Ray Flux using Daejeon and Jang Bogo Neutron Monitors

2017 ◽  
Author(s):  
Jongil Jung ◽  
Suyeon Oh ◽  
Yu Yi ◽  
Paul Evenson ◽  
Roger Pyle ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Cosmic Ray ◽  
Neutron Monitors ◽  
Cosmic Ray Flux

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.

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