Average features of the interplanetary shock observed with the Global Muon Detector Network (GMDN) (original) (raw)

Coronal Mass Ejection, Geomagnetic Storms and Ground-Based Cosmic Ray Intensity Decreases

2014

Events of geomagnetic storms and cosmic ray intensity Forbush-decreases are compared with coronal mass ejections. On the basis of catalogue of interplanetary shocks the predictors of ground manifestations of various types of the events are extracted: (a) geomagnetic storms with a Forbush decreases; (b) geomagnetic storms without Forbush-decreases; (c) Forbush-decreases without a magnetic storms; (d) events without geomagnetic storms and Forbush-decreases. The dependence of four helioand geoeffects (а-d) on a compression ratio σ and interplanetary shock velocity Vsh is considered. There were revealed the features of these parameters which show a central or peripheral location of the heliogeoeffective structures in the body of coronal mass ejection. The results of the ground diagnostics of their location are in a qualitative agreement with the normal n orientation of the registered interplanetary shocks.

Extended Cosmic Ray Decreases with Strong Anisotropy after Passage of Interplanetary Shocks

The Astrophysical Journal

The passage of an interplanetary shock and/or interplanetary coronal mass ejection often causes a rapid decrease in the Galactic cosmic-ray (GCR) flux, known as a Forbush decrease, followed by a recovery of the flux over some days. These local effects are of short duration and strongly rigidity dependent, with higher-rigidity particles exhibiting much weaker effects. In contrast, we present data for two events in which the cosmic-ray flux gradually decreased for about 1 week after shock passage, then recovering over the following week, with the highest anisotropy levels observed throughout Solar Cycle 24. These extended decreases have a weak rigidity dependence and are much more prominent in observations at higher cutoff rigidity, where the initial Forbush decrease is not clearly detected and other variations are generally weak, as we demonstrate using data from the Princess Sirindhorn Neutron Monitor at Doi Inthanon, Thailand with a cutoff rigidity of about 17 GV. We propose that t...