Geomagnetic pulsation generation as a result of whistler wave scattering

Nonlinear scattering of whistler mode waves by kinetic Alfven waves (KAWs) is considered. The evolution of whistler mode wave decay instability in tim e and two spatial dimensions is studied under the approximation of two-flui d magnetohydrodynamics. It is shown that efficient coupling between whistle r waves and KAWs is possible due to the finite Larmor radius effect for Alf ven waves. The considered process can lead to significant enhancement of KA Ws. The nonlinear scattering of whistler waves by KAWs is proposed as a pos sible mechanism of enhancement and generation of geomagnetic pulsations in the magnetosphere and ionosphere of the Earth. (C) 1999 American Institute of Physics. [S1070-664X(99)02101-1].