3d and 2d Transport Equations of Galactic Cosmic Rays in Modern Heliosphere Models – I

The paper presents the results of the reduction of the full three-dimensional (in spatial coordinates) transport equation of galactic cosmic rays in longitude. It is shown that in the simplest case of the quasi-stationary equation, usually used to describe the intensity of galactic cosmic rays near solar activity minima, when only the coefficient describing the particle drift depends on longitude, the resulting axisymmetric equation does not reduce to an a priori 2D-equation, in which the longitudinal component of the particle drift velocity is dropped from consideration. The presence of the drift modulation mechanism leads to the fact that in the 2D reduced equation the total drift velocity acquires a factor −1 ≤ F ≤ 1, depending on the latitude, and an additional term appears in the equation, taking into account the contribution of the three-dimensionality of the original equation.