Quoted from: https://ccmc.gsfc.nasa.gov/models/models_at_glance.php

Model Description
The VERB model calculates the distribution function of the electron radiation belt in three dimensions: one in a spatial coordinate (L*), and two are in phase space (pitch angle and particle energy).

The model advances the time-dependent evolution of the electron distribution using the Fokker-Planck equation with pitch angle and energy diffusion coefficients representing field-aligned wave propagation for dayside and nightside chorus, plasmaspheric hiss and electomagnetic ion cyclotron (EMIC) waves. The diffusion coefficients depend on the planetary K (Kp) index, which is the primary time-dependent model input.

The diffusion equation (Eq. 6 in Subbotin and Shprits, 2009), is evaluated between 1 ≤ L* ≤ 7 in an energy range from 0.01 MeV < E < 10 MeV at L*=7 and 0.05 MeV ≤ E ≤ 24 MeV at L*=4. Larger energies are considered at lower L* values.

Phase space densities at the atmosphere (L*=1) are set to zero to represent losses. Time-dependent particle flux observations at geosynchronous orbit can be used at the outer boundary (L*=7). The default flux distribution function is an exponential fit to a typical, stationary energy spectrum.

References and relevant publications
Subbotin, D. A. and Y. Y. Shprits (2009),Three-dimensional modeling of the radiation belts using the Versatile Electron Radiation Belt (VERB) code,Space Weather, 7, S10001,doi:10.1029/2008SW000452.

Shprits, Y. Y. , D. Subbotin, and B. Ni (2009),Evolution of electron fluxes in the outer radiation belt computed with the VERB code,J. Geophys. Res., 114, A11209,doi:10.1029/2008JA013784.

Subbotin, D., Y. Shprits, and B. Ni (2010),Three-dimensional VERB radiation belt simulations including mixed diffusion,J. Geophys. Res., 115, A03205,doi:10.1029/2009JA015070.

CCMC Contact(s)
Lutz Rastaetter
301-286-9571

Developer Contact(s)
Y.Y. Shprits