Unusual behaviour caused by interplanetary turbulences in cosmic ray intensity

Abstract

The unusually high/low amplitude anisotropic wave train events (HAEs/LAEs) in cosmic ray intensity using the ground based Deep River neutron monitor data have been studied during the period 1991-94. It has been observed that the phase of diurnal anisotropy for majority of HAE/LAE cases remains in the same co-rotational direction. The phase of diurnal anisotropy has shifted to later hours for some of the HAE cases, whereas it shifts towards earlier hours for some of the LAE cases. Further, for majority of HAE/LAE cases, the amplitude of semi-diurnal anisotropy remains statistically the same; whereas, the phase of semi-diurnal anisotropy for all HAE/LAE cases has shifted to later hours. Furthermore, for tri-diurnal anisotropy the phase shifts towards later hours for both type of events; while, amplitude remains statistically the same. The interplanetary magnetic field (IMF) and solar wind plasma (SWP) parameters during these events are also investigated. The possible sources causing these types of unusual events have been proposed.