Abstract:
A working Direct Analytic Method (DAM) model is envisaged to explain the normal modes of
poloidal Alfven waves in the Earth's magnetosphere. The model solves the ideal, cold, magnetohydrodynamic
(MHD) equations associated with transverse components of the magnetic perturbations in a dipolar magnetic
field. DAM model is used to study the transverse poloidal waves in different regions of magnetosphere
characterized by their L-value and different plasma variability. The plasma density distribution is assumed to
be governed by the standard power law, 1/rm, where r is the geocentric distance of any point of interest on the
field line and m is the density index. The eigen frequencies and spatial structures are obtained analytically under
different ideal ionospheric boundary conditions and the results are compared with the numerical solutions to
establish the validity of the model. DAM, being an analytic model, is used to explain the distinctive structural
features of transverse poloidal waves which are obtained under different boundary conditions, for different
density indices. Furthermore, the application of the analytic model in the computation of eigen frequency as
well as plasma density is demonstrated under different observational scenario.
