A Plasmasphere/Ring-Current/Radiation-Belt Interaction Model

The plasmasphere/ring-current/radiation-belt is an interacting 
system. The magnetic field generated by the ring current changes the 
drift paths of energetic particles. Pressure gradients in the ring 
current produce the region 2 field aligned currents, which close in 
the ionosphere and create an electric field that acts to shield the 
lower-latitude region from the full force of convection. In turn, 
this shielding field alters the transport of the ring current and 
plasmaspheric plasmas. Furthermore, the anisotropy in the ring 
current plasmas can excite waves that cause pitch-angle and energy 
diffusion of radiation belt and ring current particles. On the other 
hand, the precipitation of energetic electrons modifies the 
ionospheric conductances, and thus the electric filed configuration 
in the magnetosphere-ionosphere (M-I) system. In the past few years, 
we have developed a Comprehensive Ring Current Model (CRCM) that 
self-consistently calculates the ionospheric electric field, and the 
ring current ion distribution that conserves the first two adiabatic 
invariants. With consideration of M-I coupling, the CRCM has produced 
remarkably good predictions of the ring current distributions and 
electric potential patterns. At the same time, we have also developed 
a global radiation belt model to predict the electron fluxes in the 
inner magnetosphere. Since all the plasma populations in the 
magnetosphere are highly coupled to each other, we have initiated 
development of a Plasmasphere/Ring-current/Radiation-belt Interaction 
Model (PRRIM). The CRCM potential will be used to drive a 
plasmasphere model to provide a precise picture of the core plasma, 
which controls the characteristics of waves that are interacting with 
the radiation belt particles. The pitch-angle and energy diffusion 
coefficients for energetic ions and electrons will be updated 
according to the instantaneous core plasma density and energetic 
particle pitch-angle distributions. The perturbation in the magnetic 
field produced by the ring current will also be considered. The 
calculated electron precipitation will be used to modify the 
ionospheric conductances in the CRCM to complete the coupling cycle. 
We will describe individual modules in the PRRIM and present results 
from a preliminary coupling effort.