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

Abstract

[1] The wave-particle interactions and associated precipitation of energetic ions/electrons play an important role in the coupling between the inner magnetosphere and the ionosphere. In this paper, we present characteristics of precipitating ring current (RC) ions/electrons and precipitating radiation belt electrons associated with wave-particle interactions in the plasmaspheric plume in the main phase of a geomagnetic storm during 8-9 May 2001. With observations of the NOAA 16 satellite, within the anisotropic zone, the peak of precipitating RC electron flux was equatorward to that of precipitating RC proton flux in a plasmaspheric plume recognized by the IMAGE and LANL-91/94 satellites. An enhancement of precipitating flux for >3 MeV electrons was simultaneously observed by NOAA 16 with the increase of precipitating RC proton flux within the anisotropic zone. Theoretical calculations of pitch angle diffusion coefficients for RC protons and for radiation belt electrons caused by electromagnetic ion cyclotron (EMIC) waves demonstrated that precipitating flux enhancements of RC protons and >3 MeV radiation belt electrons are a result of EMIC wave-particle interactions in the plasmaspheric plume. Our result suggests that EMIC waves in the plasmaspheric plume can scatter not only RC ions but also radiation belt electrons into the loss cone, which cause the loss of the RC ions and radiation belt electrons.

Van Allen Probes, THEMIS, GOES, and Cluster observations of EMIC waves, ULF pulsations, and an electron flux dropout

“…The EMIC waves observed by THEMIS‐A continue all the way out to the magnetopause on the dayside. The location of the THEMIS‐A EMIC wave observations in the afternoon sector suggests the presence of a plasmaspheric plume, as EMIC waves have been associated with drainage plumes in the afternoon sector by past studies [ Morley et al , ; Fraser et al , ; Halford et al , ; Yuan et al , , ]. These waves may be generated by enhanced cold plasma densities within the plume [ Morley et al , ; Halford et al , ].…”

In situ evidence of the modification of the parallel propagation of EMIC waves by heated He+ ions

“…EMIC waves play an important role in the inner magnetospheric dynamics through wave‐particle interaction [ Jordanova et al ., ; Fok et al ., ; Yuan et al ., , ]. Due to resonant interaction with MeV electrons, EMIC waves can also lead to the precipitation of MeV electrons and be considered as the dominant contributor to the rapid loss of radiation belt electrons loss [e.g., Summers and Thorne , ; Bortnik et al ., ; Millan and Thorne , ; Ukhorskiy et al ., ; Shprits et al ., ; Yuan et al ., ].…”

The story of plumes: the development of a new conceptual framework for understanding magnetosphere and ionosphere coupling

“…What is now clear is that plumes connect the equatorial F region ionosphere to the dayside magnetopause and the nightside magnetotail plasma sheet (e.g., Su et al, 2001a, b;Horvath and Lovell, 2011;Walsh et al, 2014a, b;Foster et al, 2014). Through the formation and evolution of the different plumes, they impact wave generation and wave-particle interactions (e.g., Summers et al, 2008;Chen et al, 2012;Halford et al, 2015), particle precipitation (Spasojević and Fuselier, 2009;Yuan et al, 2011Yuan et al, , 2013, ion outflow (e.g., Zeng and Horowitz, 2008;Tu et al, 2007), local-time asymmetries in ULF wave field-line resonance (FLR) signatures (e.g., Archer et al, 2015;Ellington et al, 2016), satellite communication and navigation systems (Ledvina et al, 2004;Basu et al, 2005;Datta-Barua et al, 2014), and even the coupling efficiency of the solar wind to the magnetosphere (Borovsky and Denton, 2006;Borovsky et al, 2013;Ouellette et al, 2016;Fuselier et al, 2016). Though we now have a new appreciation and understanding of plumes, there are still many unanswered questions on their formation (e.g., Kelley et al, 2004;Horvath and Lovell, 2011;Zou et al, 2013Zou et al, , 2014Borovsky et al, 2014) and impact on global magnetospheric dynamics McFadden et al 2008;Walsh et al, 2014Walsh et al, , 2015.…”