Time-Dependent 2d Model Compared with Observations During the 1974 Mini Cycle |
| |
Authors: | G Wibberenz SES Ferreira MS Potgieter HV Cane |
| |
Institution: | (1) IEAP, University of Kiel, D-24118 Kiel, Germany;(2) Unit for Space Physics, Potchefstroom University for CHE, South Africa;(3) LHEA, NASA/Goddard Space Flight Center, Greenbelt, MD, 20771, U.S.A |
| |
Abstract: | The 1974 mini-cycle is a medium term cosmic ray modulation event with about one year duration. It occurred in an A>0 epoch of solar magnetic polarity during conditions of low activity, but with an increase in the latitudinal extent of the
heliospheric current sheet (tilt angle α) and the magnitude B of the heliospheric magnetic field. This cosmic ray decrease can be used to test the hypothesis that such large scale decreases
(mini cycles) may be caused primarily by a combination of changes in α and B. For this purpose a fully time-dependent 2D model of solar modulation is used, which includes the effects of global and current
sheet drifts, and anisotropic perpendicular diffusion. Such models have been used successfully to describe the proton energy
spectrum as well as the radial and latitudinal gradients near 1 AU. Comparison of the model solutions with the observed decrease
for 1.8 GV protons allows us to study the combined influence of variable drift and diffusion effects throughout the event.
This revised version was published online in August 2006 with corrections to the Cover Date. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|