Frequencies and polarizations of ULF waves in the magnetosphere: effects of ionospheric Pedersen and Hall conductances.

We extended a recently developed Field line Resonance model based on covariant-contravariant formalism to include finite ionospheric conductivities. The nature of our model allows a straightforward incorporation of both Pedersen and Hall conductivities, while earlier studies were restricted to using Pedersen conductance only. In agreement with previous studies we find that Pedersen conductance results primarily in attenuation of the standing wave; its effect on the frequency and polarization of the wave is generally small. In contrast, Hall conductance by itself does not lead dissipation of the wave, but modifies wave's polarization. Thus, including ionospheric Hall conductance is extremely important for realistic modeling polarizations of Ultra Low Frequency wave, which have significance for electron energization in the magnetosphere. We present results applying our new ULF wave model to various background magnetic fields, such as idealized "compressed dipole" and Tsyganenko fields.