The role of cyclic solar magnetic field variations in the long-term cosmic ray modulation

2009 ◽  
Vol 43 (4) ◽  
pp. 673-679 ◽  
Author(s):  
R.T. Gushchina ◽  
A.V. Belov ◽  
V.N. Obridko ◽  
B.D. Shelting
Author(s):  
Fraser Baird ◽  
Alexander MacKinnon

For the first time, based on the experimental data of AMS-02, a three-parameter spectrum of variations of ga - lactic cosmic rays was obtained in the range of rigidity 1- 20 GV, to which neutron monitors are most sensitive. It was found that during the period of negative polarity of the solar magnetic field, a power-law spectrum of va - riations is observed with a strong exponential decay in the region of high rigidity. When the polarity changes to positive at the beginning of the new 24th solar cycle, the spectrum of cosmic ray variations becomes purely po- wer-law. The transition to the experimentally obtained spectrum of variations will make it possible to remove a number of uncertainties and increase the accuracy of the analysis of data from the ground network of detectors. This will make it possible to retrospectively obtain fluxes of galactic protons with an average monthly resolution for the period of the space era based on ground-based monitoring.


1993 ◽  
Vol 98 (A3) ◽  
pp. 3585-3603 ◽  
Author(s):  
John W. Bieber ◽  
Jiasheng Chen ◽  
William H. Matthaeus ◽  
Charles W. Smith ◽  
Martin A. Pomerantz

1999 ◽  
Vol 26 (5) ◽  
pp. 565-568 ◽  
Author(s):  
H. V. Cane ◽  
G. Wibberenz ◽  
I. G. Richardson ◽  
T. T. von Rosenvinge

Solar Physics ◽  
2019 ◽  
Vol 294 (9) ◽  
Author(s):  
Krzysztof Iskra ◽  
Marek Siluszyk ◽  
Michael Alania ◽  
Witold Wozniak

Abstract In the present article, we analyze long-term changes in the intensity of galactic cosmic rays (GCRs) in different polarity epochs of the solar magnetic cycles from 1959 to 2014. Our purpose is to carry out a study of the delay time (DT) between the changes of the GCR intensity and various parameters characterizing the conditions in the heliosphere. We prove the existence of varying DTs between the changes of GCR intensity and the parameters characterizing solar activity, such as sunspot number and tilt angle. Based on our investigation, we obtained different DTs in epochs with different global solar magnetic field polarities. We conclude that the observed DTs are very important parameters for the study of GCR transport in the heliosphere.


2003 ◽  
Vol 21 (6) ◽  
pp. 1275-1288 ◽  
Author(s):  
B. Heber ◽  
G. Sarri ◽  
G. Wibberenz ◽  
C. Paizis ◽  
P. Ferrando ◽  
...  

Abstract. Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in December 1997, and its second fast latitude scan in September 2000. In contrast to the first fast latitude scan in 1994/1995, during the second fast latitude scan solar activity was close to maximum. The solar magnetic field reversed its polarity around July 2000. While the first latitude scan mainly gave a snapshot of the spatial distribution of galactic cosmic rays, the second one is dominated by temporal variations. Solar particle increases are observed at all heliographic latitudes, including events that produce >250 MeV protons and 50 MeV electrons. Using observations from the University of Chicago’s instrument on board IMP8 at Earth, we find that most solar particle events are observed at both high and low latitudes, indicating either acceleration of these particles over a broad latitude range or an efficient latitudinal transport. The latter is supported by "quiet time" variations in the MeV electron background, if interpreted as Jovian electrons. No latitudinal gradient was found for >106 MeV galactic cosmic ray protons, during the solar maximum fast latitude scan. The electron to proton ratio remains constant and has practically the same value as in the previous solar maximum. Both results indicate that drift is of minor importance. It was expected that, with the reversal of the solar magnetic field and in the declining phase of the solar cycle, this ratio should increase. This was, however, not observed, probably because the transition to the new magnetic cycle was not completely terminated within the heliosphere, as indicated by the Ulysses magnetic field and solar wind measurements. We argue that the new A<0-solar magnetic modulation epoch will establish itself once both polar coronal holes have developed.Key words. Interplanetary physics (cosmic rays; energetic particles; interplanetary magnetic fields)


2019 ◽  
Vol 37 (3) ◽  
pp. 299-314 ◽  
Author(s):  
Christoph Lhotka ◽  
Yasuhito Narita

Abstract. Current knowledge on the description of the interplanetary magnetic field is reviewed with an emphasis on the kinematic approach as well as the analytic expression. Starting with the Parker spiral field approach, further effects are incorporated into this fundamental magnetic field model, including the latitudinal dependence, the poleward component, the solar cycle dependence, and the polarity and tilt angle of the solar magnetic axis. Further extensions are discussed in view of the magnetohydrodynamic treatment, the turbulence effect, the pickup ions, and the stellar wind models. The models of the interplanetary magnetic field serve as a useful tool for theoretical studies, in particular on the problems of plasma turbulence evolution, charged dust motions, and cosmic ray modulation in the heliosphere.


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