Characteristics of precipitating energetic ions/electrons associated with the wave‐particle interaction in the plasmaspheric plume

Abstract

[1] In this paper, we present characteristics of precipitating energetic ions/electrons associated with the wave-particle interaction in the plasmaspheric plume during the geomagnetic storm on July 18, 2005 with observations of the NOAA15 NOAA16, IMAGE satellites and Finnish network of search coil magnetometers. Conjugate observations of the NOAA15 satellite and the Finnish network of search coil magnetometers have demonstrated that a sharp enhancement of the precipitating ion flux is a result of ring current (RC) ions scattered into the loss cone by EMIC waves. Those precipitating RC ions lead to a detached subauroral proton arc observed by the IMAGE FUV. In addition, with observations of NOAA15 and NOAA16, the peak of precipitating electron flux was equatorward to that of precipitating proton flux, which is in agreement with the region separation of ELF hiss and EMIC waves observed by the Cluster C1 in the Yuan et al. (2012) companion paper. In combination with the result of the companion paper, we demonstrate the link between the wave activities (ELF hiss, EMIC waves) in plasmaspheric plumes and energetic ion/electron precipitation at ionospheric altitudes. Therefore, it is an important characteristic of the plasmaspheric plumes-RC-ionosphere interaction during a geomagnetic storm that the precipitation of energetic protons is latitudinally separated from that of energetic electrons.Citation: Yuan, Z., Y. Xiong, D. Wang, M. Li, X. Deng, A. G. Yahnin, T. Raita, and J. Wang (2012), Characteristics of precipitating energetic ions/electrons associated with the wave-particle interaction in the plasmaspheric plume, J. Geophys.

Statistical analysis of EMIC waves in plasmaspheric plumes from Cluster observations

“…[] and Yuan et al . [] on the basis of observations of the energetic proton and electron precipitation.…”

Energetic ions scattered into the loss cone with observations of the Cluster satellite

“…For example, Liang et al (2014) showed simultaneous observations of EMIC waves excited in the CPS and loss of energetic protons. In the plasmapause or plasmaspheric plumes, in situ satellite observations have also shown that EMIC waves can scatter ring current protons into the loss cone (Erlandson and Ukhorskiy, 2001;Yuan et al, 2012b). However, to our knowledge, it is seldom reported that in situ satellite observation of energetic ions scattered into the loss cone during the satellite's passage from the plasma sheet into the plasmapause or plasmaspheric plumes.…”

“…The interaction between ring current (RC) ions and EMIC waves in the plasmapause or plasmaspheric plumes can lead to the scattering of RC ions into the loss cone and precipitating into the atmosphere at subauroral latitudes (Jordanova et al, 2007;Yahnin et al, 2009;Spasojević and Fuselier, 2009;Yuan et al, 2010). As a result, the low-altitude NOAA spacecraft crossing the auroral zone from high to low latitudes firstly detects an isotropic proton flux distribution and subsequently detects a drop of the proton flux within the loss cone and still a strong flux of trapped particles at lower latitudes (the anisotropic zones) (Yahnin et al, 2006;Yuan et al, 2011Yuan et al, , 2012bYuan et al, , 2013. In the isotropic zones, the curved field line geometry in the magnetotail has been considered as a key mechanism causing the protons in the central plasma sheet (CPS) to be pitch angle scattered into the loss cone and subsequently precipitate in the ionosphere (e.g., Sergeev et al, 1983;Buchner and Zelenyi, 1986;Ashour-Abdalla et al, 1990;Liang et al, 2013).…”

“…In the isotropic zones, the curved field line geometry in the magnetotail has been considered as a key mechanism causing the protons in the central plasma sheet (CPS) to be pitch angle scattered into the loss cone and subsequently precipitate in the ionosphere (e.g., Sergeev et al, 1983;Buchner and Zelenyi, 1986;Ashour-Abdalla et al, 1990;Liang et al, 2013). In the anisotropic zones, the NOAA spacecraft can observe enhancement of the precipitating ion flux at subauroral latitudes, which is a result of precipitating RC ions scattered into the loss cone by EMIC waves (Yahnin et al, 2002(Yahnin et al, , 2006Jordanova, et al, 2007;Yuan et al, 2012b). To better reveal the key mechanisms scattering protons into the loss cone, in situ satellite observations of simultaneous loss of energetic protons and EMIC waves are very necessary.…”

Simultaneous observations of precipitating radiation belt electrons and ring current ions associated with the plasmaspheric plume

“…As shown in Figure , within the anisotropic zone, the NOAA 16 observed enhancements of precipitating RC ion/electron flux in the plasmaspheric plume. In addition, the peak of precipitating RC electron flux is equatorward to that of precipitating RC proton flux, which is in accordance with previous observations of precipitating RC ion/electron flux in the plasmaspheric plume [ Yahnin et al ., ; Yahnin and Yahnina , ; Yuan et al ., ]. Since other satellites or ground‐based magnetometers did not perform the conjugate observations with NOAA 16 during the RC ion precipitation shown in Figure , we could not obtain the data of EMIC waves.…”