Using the NARMAX approach to model the evolution of energetic electrons fluxes at geostationary orbit

Recently published data from Reeves et al. (2011) on the fluxes of 1.8–3.5 MeV electrons at geostationary orbit are subjected to Error Reduction Ratio (ERR) analysis in order to identify the parameters that control variance of these fluxes. ERR shows that it is the solar wind density not the velocity that controls most of the variance of the energetic electrons fluxes. High fluxes are observed under the conditions of low density in absolute majority of cases. Under the condition of fixed density the dependence of fluxes upon the velocity is the following: fluxes increase with the velocity reaching some saturation level. Both the level of saturation and the value of the velocity where it is achieved decrease with the increase of solar wind density. Key Points Use of ERR enables us to rank parameters effecting the radiation belt fluxes Density has the greatest influence, not velocity Flux saturation level and velocity distribution depend upon density