On the heliolatitudinal variation of the galactic cosmic-ray intensity. Comparison with Ulysses measurements (original) (raw)
We study the dependence of cosmic rays with he-liolatitude using a simple method and compare the results with the actual data from Ulysses and IMP spacecraft. We reproduce the galactic cosmic-ray heliographic latitudinal intensity variations, applying a semi-empirical, 2-D diffusion-convection model for the cosmic-ray transport in the inter-planetary space. This model is a modification of our previous 1-D model (Exarhos and Moussas, 2001) and includes not only the radial diffusion of the cosmic-ray particles but also the latitudinal diffusion. Dividing the interplanetary region into " spherical magnetic sectors " (a small heliolatitudinal extension of a spherical magnetized solar wind plasma shell) that travel into the interplanetary space at the solar wind velocity , we calculate the cosmic-ray intensity for different he-liographic latitudes as a series of successive intensity drops that all these " spherical magnetic sectors " between the Sun and the heliospheric termination shock cause the unmodu-lated galactic cosmic-ray intensity. Our results are compared with the Ulysses cosmic-ray measurements obtained during the first pole-to-pole passage from mid-1994 to mid-1995.
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