HR: 1400h
AN: SM33C-03    [Abstracts]
TI: AKR Emissions During Magnetic Storms
AU: * da Costa, E
EM: junior@plasma.inpe.br
AF: LAP - Instituto Nacional de Pesquisas Espaciais, Avenida dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos, SP 12227010, Brazil
AU: Alves, M V
EM: virginia@plasma.inpe.br
AF: LAP - Instituto Nacional de Pesquisas Espaciais, Avenida dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos, SP 12227010, Brazil
AU: Gonzalez, W D
EM: gonzalez@dge.inpe.br
AF: DGE - Instituto Nacional de Pesquisas Espaciais, Avenida dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos, SP 12227010, Brazil
AB: It is well known that the Auroral Kilometric Radiation (AKR) is amplified during magnetic substorms, presenting a good correlation with the AE index. However, recent studies have shown that AKR disappears during the initial and main phases of some magnetic storms (MS), in spite of the large enhancements of AE index and field- aligned currents. In such cases, radiation activates strongly in the recovery phase of these MS. Observations suggest that the field-aligned electric field, which accelerates precipitating electrons and drives field-aligned currents, is not formed in the initial and main phases of MS when AKR disappears. Our objective here is to quantify AKR emissions, starting from the AKR spectrograms, and to investigate how solar wind parameters could influence these emissions during magnetic storms. In order to get such results, it was developed a numerical index based on the intensity of the auroral radiation exhibited by the dynamical spectrograms. This numerical index represents the intensity of the radiation and was called AKR index. Events for those it was possible to obtain the AKR spectrograms, space plasma parameters and the geomagnetic indices AE and Dst were selected. Among the chosen events, in some of them AKR is emitted during all the period of the storm, whereas in others AKR is not present during the initial and main phases. By analyzing these events, we found that the disappearance of AKR is related to a high density in the plasma sheet, while the space plasma parameter that better correlates with AKR is the solar wind speed.
DE: 0654 Plasmas
DE: 2704 Auroral phenomena (2407)
DE: 2716 Energetic particles: precipitating
DE: 2784 Solar wind/magnetosphere interactions
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly