Different evolution patterns of subauroral polarization streams (SAPS) during intense storms and quiet time substorms

In this letter, we present multisatellite observations of the evolution of subauroral polarization streams (SAPS) during intense storms (ISs) and quiet time substorms (QSs). SAPS occurred during 37 ISs and 30 QSs were analyzed. Generally, SAPS occur after the southward turning of the interplanetary magnetic field (IMF) with time lags of 0-1.5 h for ISs and 0-2.5 h for QSs. SAPS usually occurred 0-3 h after the beginning of storm main phases and 0-2 h after the substorm expansion onsets. The lifetimes of SAPS are generally longer than the durations of southward IMF and storm main phases. During QSs, the lifetimes of SAPS are shorter than the duration of the ISs. Superposed epoch analysis shows different evolution patterns of SAPS during ISs and QSs. The results of this study provide both physical insight and constrains to modeling the magnetosphere-ionosphere-thermosphere coupling.