  In this study, we present initial results of the coupling between the Inner
Magnetospheric Particle Transport and Acceleration Model (IMPTAM) and the
Versatile Electron Radiation Belt (VERB-3D) code. IMPTAM traces electrons of 10
- 100 keV energies from the plasma sheet (L = 9 Re) to inner L-shell regions.
The flux evolution modeled by IMPTAM is used at the low energy and outer L*
computational boundaries of the VERB code (assuming a dipole approximation) to
perform radiation belt simulations of energetic electrons. The model was tested
on the March 17th, 2013 storm, for a six-day period. Four different simulations
were performed and their results compared to satellites observations from Van
Allen probes and GOES. The coupled IMPTAM-VERB model reproduces evolution and
storm-time features of electron fluxes throughout the studied storm in
agreement with the satellite data (within ~0.5 orders of magnitude). Including
dynamics of the low energy population at L* = 6.6 increases fluxes closer to
the heart of the belt and has a strong impact in the VERB simulations at all
energies. However, inclusion of magnetopause losses leads to drastic flux
decreases even below L* = 3. The dynamics of low energy electrons (max. 10s of
keV) do not affect electron fluxes at energies >= 900 keV. Since the
IMPTAM-VERB coupled model is only driven by solar wind parameters and the Dst
and Kp indexes, it is suitable as a forecasting tool. In this study, we
demonstrate that the estimation of electron dynamics with
satellite-data-independent models is possible and very accurate.
