SIMULATION OF PROTON RADIATION BELT FORMATION DURING THE MARCH 24, 1991 SSC

The rapid formation of a new proton radiation belt at L similar or equ al to 2.5 following the March 24, 1998 Storm Sudden Commencement (SSC) observed at the CRRES satellite is modelled using a relativistic guid ing center test particle code. The SSC is modelled by a bipolar electr ic field and associated compression and relaxation in the magnetic fie ld, superimposed on a dipole magnetic field. The source population con sists of both solar and trapped inner zone protons. The simulations sh ow that while both populations contribute to drift echoes in the 20-80 MeV range, primary contribution is from the solar protons. Proton acc eleration by the SSC differs from relativistic electron acceleration i n that different source populations contribute and nonrelativistic con servation of the first adiabatic invariant leads to greater energizati on of protons for a given decrease in L. Model drift echoes and flux d istribution in L at the time of injection compare well with CRRES obse rvations.