  Electromagnetic (radio, visible-light, UV, EUV, X-ray and gamma-ray) emission
generated by solar and stellar flares often contains pronounced quasi-periodic
pulsations (QPP). Physical mechanisms responsible for the generation of
long-period QPP (with the periods longer than one second) are likely to be
associated with MHD processes. The observed modulation depths, periods and
anharmonicity of QPP suggest that they can be linked with some kind of MHD
auto-oscillations, e.g. an oscillatory regime of magnetic reconnection. Such
regimes, of both spontaneous and induced nature, have been observed in
resistive-MHD numerical simulations. The oscillations are essentially nonlinear
and non-stationary. We demonstrate that a promising novel method for their
analysis is the Empirical Mode Decomposition technique.
