NONTYPICAL Pc5 PULSATIONS IN THE OCTOBER 2003 SUPERSTORM RECOVERY PHASE

The recovery phases of the super strong magnetic storms that happened in October 2003 was accompanied by very large (up to 500–600 nT) morning and daytime Pc5 geomagnetic pulsations. The afternoon pulsations were observed with similar waveforms, intensities, and polarization in the unusually wide latitude area. The wave spectra changed with time and events but they did not change with latitudes. As a rule, the spectral maxima were latitudeindependent. The main behavior of these pulsations did not coincide with that expected from the field line resonance (FLR) model which is generally accepted for the “classic” morning Pc5 wave generation. The global maps of the Pc5 amplitude distribution were computed by using the multipoint observations. The unusual deep latitude Pc5 penetration was found. The global area of the enhanced Pc5s involved the relatively narrow latitude morning band and very broad (from polar to middle/low latitudes) afternoon region. The afternoon Pc5 occurrence area was divided into high and low latitude parts, separated by the wave amplitude minimum and the wave polarization reverse. It was suggested that the considered daytime Pc5 pulsations were of non-resonant nature.