Stratified Subauroral Ion Drift (SSAID)

Abstract

AbstractIn this paper, the internal structuring of Polarization Jet (PJ)/Subauroral Ion Drift (SAID) is studied. It is shown that PJ/SAID consists of several Polarization Jet Strata (PJS) of electron density and temperature. A new type of phenomena has been discovered called Stratified Subauroral Ion Drift (SSAID), which is a PJ/SAID containing small‐scale PJS. Internal small‐scale structure of SSAIDs is measured during various geomagnetic events using data from NorSat‐1, DMSP F‐17 and F‐18 satellites. High resolution measurements on the Norsat‐1 satellite make it possible to detect and study small‐scale structures inside the PJ/SAID, that is, SSAID. The data from DMSP satellites is used to determine explicitly the presence of PJ/SAID during the considered geomagnetic events. Results show that SSAID consist of 2–4 large PJS and from a few units to several tens of small PJS. Large PJS have a size of 0.2°–0.3° latitude and small PJS have a size of <0.1°. Several suggestions regarding possible physical mechanisms of production of SSAID and PJS are presented.