Study of high amplitude anisotropic wave trains along with interplanetary plasma parameters

The first three harmonics (diurnal/semi-diurnal/tri-diurnal) of high amplitude anisotropic wave trains of cosmic ray intensity over the period 1991-1994 have been investigated for Deep River neutron monitoring station. Our study reveals that the diurnal time of maximum i.e. phase remains in the corotational/18 Hr direction, whereas the time of maximum for semi-diurnal anisotropy has no definite trend as compared to the quiet days (days on which the transient magnetic variations are regular and smooth) annual average for majority of the HAE events. The phase of the tri-diurnal anisotropy significantly shift towards later hours as compared to the quiet day annual average. It is noticed that these events are not caused either by the high-speed solar wind streams or by the sources on the Sun responsible for producing these streams such as polar coronal holes. The amplitude of tri-diurnal anisotropy for HAE events is observed to remain high for negative polarity of north-south component of interplanetary magnetic field (Bz), whereas it is found to remain slightly low for positive polarity of Bz showing a negative correlation. The amplitude of the tri-diurnal anisotropy is observed to increase with the decrease in the value of disturbance storm time index (Dst) showing a negative correlation. PACS: 96.40.Kk, 96.40. -z, 96.40.cd