The effects of dynamic ionospheric outflow on the ring current

Abstract

[1] The importance of ionospheric O + on the development of the storm time ring current is recognized but not well understood. The addition of this outflow in global MHD models has the potential to change the magnetic field configuration, particle densities and temperatures, and the convection electric field. This makes including heavy ion outflow in ring current simulations difficult, as this addition cannot be easily decoupled from a host of other changes. This study attempts to overcome this problem by using three coupled models, PWOM, RIM, and BATS-R-US, to drive a ring current model, RAM-SCB. The differences in drivers when outflow is included and is not included are compared to see how outflow changes ring current input. It is found that including this outflow reduces the convection electric field, lowers the plasma sheet number density and temperature, and increases the complexity of the plasma sheet ion composition both temporally and spatially. These changes cause an overall reduction in ring current energy density. Further simulations that attempt to isolate these effects find that the most important change in terms of ring current development is the drop in convection electric field. Local time dependencies of O + injections are found to be nontrivial as well. Capturing all of these effects requires a whole system, first-principles approach.

Circulation of Heavy Ions and Their Dynamical Effects in the Magnetosphere: Recent Observations and Models

“…Additionally, if MHD predictions of reduced CPCP values resulting from O + outflow are correct, the E × B drift of fresh plasma will be greatly diminished. Welling et al (2011) demonstrated that these two factors caused weak Earthward penetration of plasma into the ring current. Warmer populations, especially those entering duskward of local midnight, could gradient-curvature drift out of the code domain without being captured.…”

“…Though this result is likely an extreme case, it demonstrates how the effects of heavy ion outflow are complex and non-linear. Other, less critical plasma sheet characteristics, such as spatial asymmetries in density and composition, also contribute to these effects (Welling et al 2011), as discussed in Sect. 4.4.…”

“…Storm time simulations of real events yield plasma sheet details that are difficult to categorize. For example, Winglee et al (2005) demonstrated that plasma temperature, peak density, and relative (Welling et al 2011) contribution of O + for a single storm can vary wildly not only in time, but with the composition of the ionospheric source. Furthermore, two subsequent substorm events modeled by Winglee and Harnett (2011) demonstrated how two events separated by only a few hours can show completely different patterns of composition and species-specific energy density.…”

“…4.2). An example of this variability is illustrated by Welling et al (2011), who used multispecies MHD and the PWOM to drive a ring current model. The top three panels of Fig.…”

Impact of Solar Wind on the Earth Magnetosphere: Recent Progress in the Modeling of Ring Current and Radiation Belts

“…This is the reason why coupled models are intensively developed and improved during recent years. Besides several cases considered here, the latest examples include: coupling between the RCM (ring current model) and Versatile Electron Radiation Belt (VERB) code (Subbotin et al, 2011); coupling between RAM-SCB code (ring current model) and BATSRUS/SWMF (MHD with the RCM) (Welling et al, 2011;Zaharia et al, 2010); coupling between two ring current models RAM and the RCM ; one way coupling between MHD Open Geospace General Circulation Model (Open GGCM) -the RCM (ring current model) (Hu et al, 2010). None of these models however is 'ideal' (including the examples presented in detail earlier) in the sense that all of them have some shortcuts.…”