Relativistic particles entering the Earth’s magnetosphere, i.e. cosmic rays and solar energetic particles, are of prime space weather interest because they can affect satellite operations, communications, and the safety of astronauts and airline crews and passengers. In order to mitigate the hazards that originate from such particles one needs to predict the cutoff latitudes of such particles a...

Simulation results from the NRL ionospheric model SAMI2 indicate that the changes in the F-region over Millstone Hill during the geomagnetic storm beginning on 3 April 2004 are primarily due to the influence of a long-lasting eastward electric field, as was previously suggested by Huang et al. [2005]. A simulation of the storm day agrees well with the observational data and shows that, compared...

[1] We present energetic neutral atom (ENA) fluxes measured by the medium energy neutral atom (MENA) imager onboard the IMAGE satellite for the geomagnetic storm of 21 October 2001 at energies of 6 and 12 keV. The fluxes indicate strong low altitude emissions close to the Earth and a nightside peak close to local midnight. The fluxes are compared with theoretical ENA fluxes calculated using the...