Time-dependent cosmic-ray modulation and global merged interaction regions

1999 ◽  
Vol 23 (3) ◽  
pp. 491-499 ◽  
Author(s):  
J.A le Roux
Keyword(s):  
Cosmic Ray ◽  
Time Dependent ◽  
Cosmic Ray Modulation ◽  
Interaction Regions

scholarly journals Modelling cosmic ray intensities along the Ulysses trajectory

2005 ◽  
Vol 23 (3) ◽  
pp. 1061-1070 ◽  
Author(s):  
D. C. Ndiitwani ◽  
S. E. S. Ferreira ◽  
M. S. Potgieter ◽  
B. Heber
Keyword(s):  
Transport Model ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Time Dependent ◽  
Global Changes ◽  
Cosmic Ray Modulation ◽  
Magnetic Field Magnitude ◽  
Additional Reduction ◽  
Charge Sign ◽  
Inner Heliosphere

Abstract. Time dependent cosmic ray modulation in the inner heliosphere is studied by comparing results from a 2-D, time-dependent cosmic ray transport model with Ulysses observations. A compound approach, which combines the effects of the global changes in the heliospheric magnetic field magnitude with drifts to establish a realistic time-dependence, in the diffusion and drift coefficients, are used. We show that this model results in realistic cosmic ray modulation from the Ulysses launch (1990) until recently (2004) when compared to 2.5-GV electron and proton and 1.2-GV electron and Helium observations from this spacecraft. This approach is also applied to compute radial gradients present in 2.5-GV cosmic ray electron and protons in the inner heliosphere. The observed latitude dependence for both positive and negative charged particles during both the fast latitude scan periods, corresponding to different solar activity conditions, could also be realistically computed. For this an additional reduction in particle drifts (compared to diffusion) toward solar maximum is needed. This results in a realistic charge-sign dependent modulation at solar maximum and the model is also applied to predict charge-sign dependent modulation up to the next expected solar minimum.

Cosmic-ray modulation, merged interaction regions, and multifractals

1993 ◽  
Vol 407 ◽  
pp. 347 ◽  
Author(s):  
L. F. Burlaga ◽  
J. Perko ◽  
J. Pirraglia
Keyword(s):  
Cosmic Ray ◽  
Cosmic Ray Modulation ◽  
Interaction Regions

Cosmic ray modulation in high and middle latitudes during solar cycles 22 and 23

2015 ◽  
Vol 93 (1) ◽  
pp. 100-104 ◽  
Author(s):  
Kingsley Chukwudi Okpala ◽  
Francisca Nneka Okeke ◽  
Anselem Ikechukwu Ugwuoke
Keyword(s):  
Cosmic Rays ◽  
Dynamic Pressure ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Proton Density ◽  
Solar Cycles ◽  
Middle Latitudes ◽  
Cosmic Ray Modulation ◽  
Interaction Regions

Galactic cosmic rays are modulated in the heliosphere primarily by the global merged interaction regions with intense magnetic fields, which leads to a decrease in galactic cosmic rays throughout the heliosphere. Using long-term averages of solar wind (SW) component parameters in addition to cosmic ray count rates of four neutron monitors with different rigidity cutoffs, we analyzed the effect of these SW components on the count rates under different interplanetary magnetic field (IMF) disturbance levels. From first-order partial correlation, we found that the IMF-B was the most dominant modulating parameter, especially during quiet conditions and the SW dynamic pressure was more effective during disturbed conditions. The influence of more subtle parameters like wind speed, Bz component, and proton density were masked by these dominant parameters: IMF total B, and SW dynamic pressure.

scholarly journals MHD flows at astropauses and in astrotails

2014 ◽  
Vol 1 ◽  
pp. 51-60 ◽  
Author(s):  
D. H. Nickeler ◽  
T. Wiegelmann ◽  
M. Karlický ◽  
M. Kraus
Keyword(s):  
Electric Fields ◽  
Large Scale ◽  
Cosmic Ray ◽  
Counter Flow ◽  
Stagnation Points ◽  
Cosmic Ray Modulation ◽  
Fluid Theory ◽  
Flow Configurations ◽  
Interaction Regions ◽  
Definition Of

Abstract. The geometrical shapes and the physical properties of stellar wind – interstellar medium interaction regions form an important stage for studying stellar winds and their embedded magnetic fields as well as cosmic ray modulation. Our goal is to provide a proper representation and classification of counter-flow configurations and counter-flow interfaces in the frame of fluid theory. In addition we calculate flows and large-scale electromagnetic fields based on which the large-scale dynamics and its role as possible background for particle acceleration, e.g., in the form of anomalous cosmic rays, can be studied. We find that for the definition of the boundaries, which are determining the astropause shape, the number and location of magnetic null points and stagnation points is essential. Multiple separatrices can exist, forming a highly complex environment for the interstellar and stellar plasma. Furthermore, the formation of extended tail structures occur naturally, and their stretched field and streamlines provide surroundings and mechanisms for the acceleration of particles by field-aligned electric fields.

Sign in / Sign up

Export Citation Format

Share Document