COSMIC RAY EVENTS RELATED TO SOLAR ACTIVITY RECORDED AT THE ATHENS NEUTRON MONITOR STATION FOR THE PERIOD 2000–2003

2005 ◽  
Vol 20 (29) ◽  
pp. 6714-6716 ◽  
Author(s):  
H. MAVROMICHALAKI ◽  
A. PAPAIOANNOU ◽  
A. PETRIDES ◽  
B. ASSIMAKOPOULOS ◽  
C. SARLANIS ◽  
...  
Keyword(s):  
Coronal Mass Ejections ◽  
Neutron Monitor ◽  
Solar Flares ◽  
Cosmic Ray ◽  
Monthly Basis ◽  
Cosmic Ray Intensity ◽  
Monitor Station ◽  
Time Period ◽  
Complete Study ◽  
Halo Cmes

In this work a complete study of 359 solar flares, 111 Halo coronal mass ejections (Halo CMEs) and 45 Partial Halo events occurred from November 2000 to November 2003, is considered. This time period characterized by an unexpected activity of the Sun, was divided into 27-day intervals starting from Bartels Rotation No. 2284 (14.10.2000) to No. 2324 (25.11.2003), generating diagrams of the cosmic ray intensity data recorded at the Athens Neutron Monitor Station. On these qualitative data presented for the first time, a mapping of all available solar and interplanetary events, such as solar flares with importance C, M and X, coronal mass ejections (Halo and Partial) was done. The existence of a connection between solar flares with CMEs and the respective connection to the Forbush effects on yearly and monthly basis are discussed. The role of extreme solar events occurred in March-April 2001 and in October-November 2003 is also considered.

scholarly journals Latitudinal and longitudinal dependence of the cosmic ray diurnal anisotropy during 2001–2014

2016 ◽  
Vol 34 (11) ◽  
pp. 1053-1068 ◽  
Author(s):  
Anastasia Tezari ◽  
Helen Mavromichalaki ◽  
Dimitrios Katsinis ◽  
Anastasios Kanellakopoulos ◽  
Sofia Kolovi ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Neutron Monitor ◽  
Cosmic Ray ◽  
Longitudinal Distribution ◽  
Solar Cycles ◽  
Field Polarity ◽  
Monthly Basis ◽  
Cosmic Ray Intensity ◽  
Asymptotic Cones ◽  
Diurnal Anisotropy

Abstract. The diurnal anisotropy of cosmic ray intensity for the time period 2001 to 2014 is studied, covering the maximum and the descending phase of solar cycle 23, the minimum between solar cycles 23 and 24, and the ascending phase and maximum of solar cycle 24. Cosmic ray intensity data from 11 neutron monitor stations located at different places around the Northern Hemisphere obtained from the high-resolution Neutron Monitor Database (NMDB) were used. Special software was developed for the calculations of the amplitude and the phase of the diurnal anisotropy vectors on annual and monthly basis using Fourier analysis and for the creation of the harmonic dial diagrams. The geomagnetic bending for each station was taken into account in our calculations determined from the asymptotic cones of each station via the Tsyganenko96 (Tsyganenko and Stern, 1996) magnetospheric model. From our analysis, it was resulted that there is a different behavior of the diurnal anisotropy vectors during the different phases of the solar cycles depending on the solar magnetic field polarity. The latitudinal and longitudinal distribution of the cosmic ray diurnal anisotropy was also examined by grouping the stations according to their geographic coordinates, and it was shown that diurnal variation is modulated not only by the latitude but also by the longitude of the stations. The diurnal anisotropy during strong events of solar and/or cosmic ray activity is discussed.

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.

Neutron monitor latitude survey of cosmic ray intensity during the 1986/1987 solar minimum

1989 ◽  
Vol 94 (A2) ◽  
pp. 1459 ◽  
Author(s):  
H. Moraal ◽  
M. S. Potgieter ◽  
P. H. Stoker ◽  
A. J. van der Walt
Keyword(s):  
Neutron Monitor ◽  
Solar Minimum ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity

The long-term variation of the cosmic radiation

1968 ◽  
Vol 46 (10) ◽  
pp. S903-S906 ◽  
Author(s):  
J. A. Lockwood ◽  
W. R. Webber
Keyword(s):  
Neutron Monitor ◽  
Cosmic Radiation ◽  
Cosmic Ray ◽  
Solar Modulation ◽  
Neutron Monitors ◽  
Cosmic Ray Intensity ◽  
Direct Measurements ◽  
Term Variation ◽  
Primary Cosmic Radiation

The variation in the cosmic-ray intensity recorded by neutron monitors from 1958 to 1965 has been investigated to deduce the form of the solar modulation of the cosmic radiation. The observed changes in the intensity at the neutron monitor stations, averaged over quarter-year periods, were compared with changes calculated using modulation functions depending upon energy, rigidity, and velocity × rigidity. These calculations were based upon the revised differential response functions deduced by Lockwood and Webber (1967). The variance between the observed and calculated changes in the neutron monitor intensities at different stations was minimized to determine the best form of the solar modulation function. We find that the change of the primary cosmic radiation, deduced from the change in the neutron monitor intensity as well as from direct measurements of the primary flux, can be described by a modulation of the form exp(–K/P) in the rigidity range 0.5 < P < 50 GV. The change between 1959 and 1965 can be fitted with K = 1.94 ± 0.09 and between 1963 and 1965 with K = 0.36 ± 0.05.

Long Duration Solar Flare Events and Cosmic Ray Modulation (1969-1992)

1994 ◽  
Vol 144 ◽  
pp. 499-502
Author(s):  
A. Antalová ◽  
K. Kudela ◽  
D. Venkatesan ◽  
J. Rybák
Keyword(s):  
Solar Cycle ◽  
Solar Flare ◽  
Solar Flares ◽  
Cosmic Ray ◽  
Flare Activity ◽  
Cosmic Ray Intensity ◽  
Cosmic Ray Modulation ◽  
Long Duration ◽  
Flare Index ◽  
Galactic Cosmic Ray

AbstractWe present here the results of the correlation analysis between the galactic cosmic ray intensity decrease p (as observed on Calgary neutron monitor station) and the occurence of SXR long-lasting (LDE-type) solar flares, represented by the LDE-type flare index FI. It is shown, that for the solar cycle with the lower monthly values of FI (the 21-st solar cycle) the correlation coefficient is slighter (about 0.4) comparing to the cycles with the higher LDE-type flare activity (about 0.6, in the 20-th and the 22-nd cycles).

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