Long‐lived plasmaspheric drainage plumes: Where does the plasma come from?

Abstract

Long-lived (weeks) plasmaspheric drainage plumes are explored. The long-lived plumes occur during long-lived high-speed-stream-driven storms. Spacecraft in geosynchronous orbit see the plumes as dense plasmaspheric plasma advecting sunward toward the dayside magnetopause. The older plumes have the same densities and local time widths as younger plumes, and like younger plumes they are lumpy in density and they reside in a spatial gap in the electron plasma sheet (in sort of a drainage corridor). Magnetospheric-convection simulations indicate that drainage from a filled outer plasmasphere can only supply a plume for 1.5-2 days. The question arises for long-lived plumes (and for any plume older than about 2 days): Where is the plasma coming from? Three candidate sources appear promising: (1) substorm disruption of the nightside plasmasphere which may transport plasmaspheric plasma outward onto open drift orbits, (2) radial transport of plasmaspheric plasma in velocity-shear-driven instabilities near the duskside plasmapause, and (3) an anomalously high upflux of cold ionospheric protons from the tongue of ionization in the dayside ionosphere, which may directly supply ionospheric plasma into the plume. In the first two cases the plume is drainage of plasma from the magnetosphere; in the third case it is not. Where the plasma in long-lived plumes is coming from is a quandary: to fix this dilemma, further work and probably full-scale simulations are needed.

Unsolved problems in plasmasphere refilling

“…In contrast Borovsky et al . [] find what appears to be drainage plumes persisting for many days during times of elevated Kp . The initial drainage of the outer plasmasphere is found to take place over 1.5–2 days and is sometimes followed by sustained, narrow‐MLT plume‐like high densities for as long as 11 or more days.…”

“…Other possible sources for this plasma are suggested by Borovsky et al . [] to be substorm disruption of the remaining interior plasmasphere, velocity‐shear instability, and the high‐latitude tongue of ionization. Notably, Krall and Huba [] find refilling within a factor of 2 of observation at L = 2 and 3 using SAMI3, but falling below observed refilling by a factor of 5 at L = 5.…”

Quantification of Energetic Electron Precipitation Driven by Plume Whistler Mode Waves, Plasmaspheric Hiss, and Exohiss

“…Plasmaspheric plumes are found to be favorable for enhancing pitch angle scattering of radiation belt electrons, thus leading to electron precipitation into the upper atmosphere (Borovsky et al, 2014;Summers et al, 2008;Zhang et al, 2018). Borovsky and Steinberg (2006) found that relativistic electron dropouts at geosynchronous orbit often coincided with the presence of plasmaspheric plumes, suggesting the potential loss of energetic electrons due to interactions with the enhanced plasma waves in plumes.…”

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

“…They are often long-lived, being observed for days at geosynchronous orbit (e.g., Borovsky et al, 2014), are usually narrow in longitude and appear at all longitudes/MLT (e.g., Moldwin et al, 1994), can have significant structure (e.g., Moldwin et al, 1994Moldwin et al, , 1995Darrouzet, et al, 2008;Sibanda et al, 2012), and can exist at any level of geomagnetic activity -though they are primarily associated with enhancements in activity (though not necessarily storms) (Moldwin et al, 2004). Figure 3 shows the occurrence of plumes observed by CRRES as a function of the Kp index compared to the distribution of Kp observed during the CRRES mission lifetime.…”

“…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. We propose that the shift in our conceptual understanding of the plasmasphere (Carpenter and Lemaire, 2004) now needs to extend down to the ionosphere and include a framework that connects the threedimensional plasmasphere-ionosphere-magnetosphere system.…”