Search for: All records

This study reports the longitudinal dependence of the field‐aligned Poynting flux in the Northern Hemisphere (NH) based on 11 years' (1999–2009) observations at ∼800 km altitude by the Defense Meteorological Satellite Program (DMSP) F13 satellite. Seasonal variations of the longitudinal distributions of the Poynting flux in both geographic and geomagnetic coordinates were statistically investigated. The net Poynting flux, which is the sum of downward and upward fluxes, is downward and peaks in the magnetic local time pre‐noon sector and near the geomagnetic pole. In geographic coordinates there is a longitudinal peak of the net Poynting flux that occurs between ∼130° and 160°W. The net Poynting flux is, in general, stronger in the western hemisphere than in the eastern hemisphere and larger in summer than in winter. These results indicate that the magnetospheric energy deposition into the northern polar upper atmosphere has obvious longitudinal and seasonal variations.

We report multisatellite observations of the oscillations in the subauroral polarization stream (SAPS) during a severe magnetic storm on 20 November 2003. The SAPS oscillations (SAPSOs) occurred during the main phase of the magnetic storm when theycomponent of the southward interplanetary magnetic field (IMFB_Y) turned from positive to negative. The SAPSOs were first observed in the premidnight sector and propagated toward the dusk sector. The formation and evolution of SAPSO corresponded well with the plasma sheet ions injection and precipitation, indicating that the SAPSOs are possibly generated by the interaction between the hot plasma sheet and the cold plasmasphere under particular conditions (e.g., change of the polarity of IMFB_Yaccompanied with a sudden enhancement of plasma sheet ion density). The hemispheric asymmetry of the SAPS channels is suggested to be related to the hemispheric differences in the ionospheric plasma condition and the ionospheric convection.