17:15 〜 18:45
[PEM10-P13] The upflow events associated with electron precipitation and BBELF observed by SS-520-3
キーワード：大気流出、上昇流
The Earth’s ionospheric atmosphere flows out from the polar regions. In addition to the bulk upflow driven by the electron precipitations, it has been suggested that heavy ions are heated in the perpendicular direction to the magnetic field by the plasma waves and then accelerated in the parallel direction by the mirror force [Yau and André., 1997].
In order to study ion outflow phenomena on the basis of in-situ observations in the cusp region, the sounding rocket SS-520-3 was launched from Ny-Ålesund, Svalbard, Norway at 10:09:25 UT on November 4, 2021. During the flight in the cusp region, the TSA (Thermal Ion Spectrum Analyzer) observed three ion upflow events in an energy range from 10 eV to 17.9 eV (Event 1: 435-450 s, Event 2: 515-545 s, Event 3: 590-630 s from the launch time). In all events, we can find increase of H+ upward flux over 10 counts/sample and simultaneous electron precipitation enhancement observed by the LEP (Low-Energy Particle analyzer). The electron precipitation enhancements are considered as dominant energy input for the upward H+ enhancement. Among three events, BBELF (Broadband Extremely Low Frequency) waves were observed in Events 2 and 3 by the LFAS (Low Frequency Analyzer System). In Events 2 and 3, enhancements of O+ upward flux were found with electron precipitations and also with BBELF waves, which were not found in Event 1. In Event 1, enhancements of O+ upward flux were not found even with electron precipitation enhancement over 300 eV. From the comparison between H+ flux and O+ flux in the three Events, it was suggested that O+ can gain less energy from the electron precipitation than H+ can gain. In addition, from the comparison between O+ in Event 1 with those in Event 2 and 3, the O+ can gain enough parallel velocity due to additional energy input from the BBELF waves. In the second half of Event 2 (535-550 s), we can find another kind of O+ enhancements without electron precipitations and only with BBELF, which are quite different from those in the first half of Event 2 and in Event 3.
In Glocer and Daldorff (2022), dependence of upflow flux on multiple energy inputs at altitudes of 1200 km and 4000 km were examined on the basis of the simulation using the Polar Wind Outflow Model [Glocer et al., 2007, 2009]. In this study, we could find SS-520-3 data showing the contribution of electron precipitation and wave-induced energy input to H+ and O+ upflow at the rocket’s altitude of approximately 700 km using data obtained by SS-520-3 and simulations. Our focus is also on the differences on the contribution of the mirror force (conservation of the first invariant) and energy inputs (electron precipitation, BBELF, etc) on the energy and flux of the H+ and O+ upflow.
In order to study ion outflow phenomena on the basis of in-situ observations in the cusp region, the sounding rocket SS-520-3 was launched from Ny-Ålesund, Svalbard, Norway at 10:09:25 UT on November 4, 2021. During the flight in the cusp region, the TSA (Thermal Ion Spectrum Analyzer) observed three ion upflow events in an energy range from 10 eV to 17.9 eV (Event 1: 435-450 s, Event 2: 515-545 s, Event 3: 590-630 s from the launch time). In all events, we can find increase of H+ upward flux over 10 counts/sample and simultaneous electron precipitation enhancement observed by the LEP (Low-Energy Particle analyzer). The electron precipitation enhancements are considered as dominant energy input for the upward H+ enhancement. Among three events, BBELF (Broadband Extremely Low Frequency) waves were observed in Events 2 and 3 by the LFAS (Low Frequency Analyzer System). In Events 2 and 3, enhancements of O+ upward flux were found with electron precipitations and also with BBELF waves, which were not found in Event 1. In Event 1, enhancements of O+ upward flux were not found even with electron precipitation enhancement over 300 eV. From the comparison between H+ flux and O+ flux in the three Events, it was suggested that O+ can gain less energy from the electron precipitation than H+ can gain. In addition, from the comparison between O+ in Event 1 with those in Event 2 and 3, the O+ can gain enough parallel velocity due to additional energy input from the BBELF waves. In the second half of Event 2 (535-550 s), we can find another kind of O+ enhancements without electron precipitations and only with BBELF, which are quite different from those in the first half of Event 2 and in Event 3.
In Glocer and Daldorff (2022), dependence of upflow flux on multiple energy inputs at altitudes of 1200 km and 4000 km were examined on the basis of the simulation using the Polar Wind Outflow Model [Glocer et al., 2007, 2009]. In this study, we could find SS-520-3 data showing the contribution of electron precipitation and wave-induced energy input to H+ and O+ upflow at the rocket’s altitude of approximately 700 km using data obtained by SS-520-3 and simulations. Our focus is also on the differences on the contribution of the mirror force (conservation of the first invariant) and energy inputs (electron precipitation, BBELF, etc) on the energy and flux of the H+ and O+ upflow.