GAMERA-Helio

GAMERA-Helio model provides a simulation of the global three-dimensional structure of the solar wind in the inner heliosphere. The grid starts by default at 21.5 solar radii from the Sun but this distance can be arbitrary as long as it is above the Afvenic surface in the solar wind. By default, the grid extends out to 220 solar radii but this distance can also be changed.

GAMERA-Helio solves ideal MHD equations with the addition of the gravity force in an inertial coordinate system. GAMERA utilizes high-order spatial reconstruction and constrained transport on finite volume grids to maintain divergence-free magnetic fields.

GAMERA-Helio MHD solution is driven by the output from the empirical coronal Wang-Sheeley-Arge (WSA) model. The WSA model provides maps of radial magnetic field and radial velocity components of the solar wind at 21.5 RS. The solar wind density is calculated using the radial velocity distribution from the empirical fit to the Helios spacecraft data. The solar wind temperature is defined from the full pressure balance in the angular directions.

By default, the model uses a uniform spherical grid. The coordinate system is such that +Z is aligned with the solar rotation axis, +X is away from Earth at the simulation time t=0 (Earth faces the center of the WSA map at t=0), and the Y-axis completes the right-handed system.

The inner boundary conditions file in HDF5 format (innerbc.h5) produced by a pre-processing Python script that uses WSA output at 21.5 RS containing Br and Vr in the fits format: MHD variables - radial magnetic field, density, temperature, radial velocity Modified Julian Date at the center of the WSA map

Grid file in HDF5 format (heliogrid.h5): The X,Y,Z locations of cell corners in spherical coordinate system

The file with input parameters in XML format containing: End time for simulation, Spin-up time GAMERA algorithmic parameters and flags

Gamera-helio outputs HDF5 files containing the 3D grid of cell corners and time steps with 3D cell-centered data on density, pressure, velocity vector, magnetic field vector, and current vector.