Low energy electrons (up to a few 100s of keV) in the plasma sheet and in the ring current can be accelerated to higher energies by various processes and become the drivers of the radiation belts dynamics. Therefore, it is important to account for the dynamics of this so called low energy seed population in the simulations of radiation belt electrons. While low energy electrons in the magnetotail are transported towards the Earth due to magnetospheric convection, the dynamics of energetic electrons inside geosynchronous orbit are largely determined by diffusive processes. Most available physics-based models only compute the evolution of one of these electron populations. However, in order to better understand the particle interactions in the inner magnetosphere a link between these models is necesary. The tool presented here targets this task by combining the two physics-based models IMPTAM and VERB-3D.
The Inner Magnetospheric Particle and Transport Acceleration Model (IMPTAM) (Ganushkina et al. 2001, 2005, 2006) traces electrons from the plasma sheet into the inner magnetospheric region using the guiding center approximation together with time dependent electric and magnetic fields. The model accounts for a number of wave particle interacctions, coulomb colissions and losses to the atmosphere. Electron distributions modeled by IMPTAM provide realistic time dependent boundary conditions to drive radiation belt simulations with the VERB-3D code (Shprits et al. 2009 and Subbotin et al. 2009), which in turn calculates the evolution of energetic electrons due to diffusive processes occuring in the inner L-shells of the magnetosphere. The combination of these two models gives birth to the IMPTAM-VERB coupled model. This 6-day radiation belt nowcast of 0.9 MeV electrons is automatically generated every 1hour using the IMPTAM-VERB coupled model.