No abstract

No abstract

No abstract

No abstract

By employing Haselgrove equations and a diffusive equilibrium model for the electron‐ion density distribution in the ionosphere, ray‐tracing computations are carried out to study the propagation characteristics of whistler waves observed in the low‐latitude ground stations. It is shown that such waves are propagated in the ionosphere in the prolongitudinal mode of propagation under the influence of suitable negative latitudinal gradients of ionization. A positive correlation between the high whistler activity at the ground and the negative latitudinal gradients of ionization existing in the ionosphere at low latitudes during the time of observation is found. This result explains satisfactorily the problem of how the whistlers are observed on the ground at low latitudes in the absence of suitable ducts in the ionosphere.

No abstract

A dispersion relation for the whistler mode wave propagation in an anisotropic warm magnetoplasma in the presence of a weak parallel electrostatic field has been derived from linearized coupled Boltzmann‐Maxwell equations with collision frequency independent of particle velocity. An expression for the growth rate has been derived in the presence of an electric field and for small temperature anisotropy (A<1) for the whistler mode wave. Under suitable approximation we recover the earlier known results. The modifications introduced in the growth rate by the electric field and temperature anisotropy have been discussed using observed plasma parameters at 6.6 RE. It is observed that growth (damping) of whistler mode waves is possible when the wave vector is parallel (antiparallel) to the static electric field. The effect of the electric field is more pronounced at low frequency (higher wave number) wave spectrum.

No abstract