Аннотация:Abstract Field-line curvature scattering (FLCS) within the plasma sheet–to–outer radiation belt transition region (hereafter PS2ORB) serves as a key driver of energy-latitude dispersion in energetic electron precipitation observed at low latitudes. This precipitation forms the isotropy boundary of electrons (IBe pattern), located between the isotropic $< 200$ keV electron fluxes of the plasma sheet and the anisotropic relativistic fluxes of the outer radiation belt. During geomagnetically active periods, the PS2ORB region becomes populated with plasma sheet injections that introduce various transient electron precipitation mechanisms, significantly complicating the structure of the IBe pattern. In this study, we show that the timescales of these precipitations can reach subsecond levels, allowing them to be interpreted as microbursts. Observations of such microbursts substantially enhance the spatial and temporal variability of the IBe pattern. By combining low-altitude ELFIN satellite measurements with high-temporal-resolution ( $\sim $40 ms) near-UV imaging photometer data from the Pulsating Aurora Imaging Photometers System project, we separate between FLCS-driven precipitation patterns that form the IBe pattern and electron scattering by whistler-mode waves, which generates microbursts. We identify, for the first time, the near-colocation of these two precipitation mechanisms within the PS2ORB region–an important feature not previously reported.
