SAMI2(Sami2 is Another Model of the Ionosphere)

SAMI2 is a model of the low- to mid-latitude ionosphere. The code treats the evolution of seven ion species (H⁺, He⁺, N⁺, O⁺, N_2⁺, NO⁺, and O_2⁺) in the altitude range 85 km to 15,000 km. All species are treated equally. Thermal balance equations are solved for three ion species (H⁺, He⁺, and O⁺) and for the electrons. SAMI2 is solved along flux tubes from hemisphere to hemisphere, and includes E x B transport perpendicular to the flux tubes. The fluid equations for ions (including inertia) are solved in an offset dipole coordinate system in the direction of the magnetic fields and the cross-field transport uses an non-orthogonal Eulearian grid. We will describe the non-orthogonal grid, showing the advantages in grid coverage using the non-orthogonal grid as compared to Lagrangian and orthogonal Eulerain grids. We will describe the cross-field transport scheme that is based on a finite-volume, donor cell algorithm. The algorithm for cross field transport is taken from techniques developed for solving the MHD equations. Finally, we will discuss a parallel version of SAMI2 using the Message Passing Interface (MPI) scheme that we have developed for use in two dimensions, and its extension to three dimensions. Resarch Sponsored by ONR.