285-293The
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