Stratified Subauroral Ion Drift (SSAID)
In 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.