Simultaneous Precipitation of Sub‐Relativistic Electron Microburst and Pulsating Aurora Electrons.

We have identified for the first time an energy‐time dispersion of precipitating electron flux in a pulsating aurora patch, ranging from 6.7 to 580 keV, through simultaneous in‐situ observations of sub‐relativistic electrons of microburst precipitations and lower‐energy electrons using the Loss through Auroral Microburst Pulsation sounding rocket launched from the Poker Flat Research Range in Alaska. Our observations reveal that precipitating electrons with energies of 180–320 keV were observed first, followed by 250–580 keV electrons 0–30 ms later, and finally, after 500–1,000 ms, 6.7–14.6 keV electrons were observed. The identified energy‐time dispersion is consistent with the theoretical estimation that the relativistic electron microbursts are a high‐energy tail of pulsating aurora electrons, which are caused by chorus waves propagating along the field line. Plain Language Summary: Microbursts, which are bursts of high energy electrons, and pulsating auroras, which periodically blink and caused by the precipitation of low energy electrons, are observed in the Earth's polar ionosphere. The detection time differences of the electrons associated with microbursts and pulsating auroras were detected by a sounding rocket. A possible mechanism for the generation of these precipitations is the interaction of electrons with a particular type of wave, known as "chorus," which propagates along geomagnetic lines. The observed energy‐time dispersion of the precipitating electrons is quantitatively consistent with theories of electron precipitation based on this interaction. Key Points: A sounding rocket observed simultaneously precipitating sub‐relativistic electron microbursts and pulsating auroral electrons250–580 keV electron precipitations were detected 0–30 ms after 180–320 keV electron precipitations in a single auroral patchThe energy dispersion of observed electrons is consistent with the theory that they are due to chorus waves propagating to higher latitudes [ABSTRACT FROM AUTHOR]