The solar wind plasma and IMF parameters, the upstream boundary conditions on the MHD code, will be obtained from the NASA WIND spacecraft, in station roughly 200 earth radii sunward of the earth. As the WIND data is received and decoded at GSFC, it will be staged to the T3D and used to steer the MHD simulation. During periods of real-time tracking of WIND by the Deep Space Net, the data should be available to the MHD code about 45 minutes before the measured plasma reaches the magnetosphere. Thus, by running the MHD code in real time, with simulation time equaling wall clock time, we can use the code results to forecast the state of the magnetosphere up to 45 minutes in advance.
The MHD code developed by J. Lyon is arguably the most successful of several that have been developed over the last decade. The fully 3D code uses a high-order nonlinear algorithm incorporating nonlinear shock and discontinuity capturing techniques to solve the ideal MHD equations on a deformed spherical mesh. It incorporates an ionosphere model with spacially varying conductivity in which the earthward boundary conditions are self-consistently calculated. The code has been shown to accurately model the position of magnetospheric boundaries as well as energy deposition in the ionosphere.
We have recently ported the code to the PSC T3D and are now tuning it for performance. We are confident that we can run the code in real time on 64 processors on the T3D using the WIND data.
The 3D hybrid code, developed by S. Brecht, has been successfully used to model the solar wind interaction with the atmosphere of Venus and Mars. This code can model the ion kinetic effects critical to shock wave is collisionless plasma, as the ions as followed as macroparticles while the electrons as modeled as an isotropic fluid. The much larger scale of the earth's magnetosphere has made a hybrid simulation impractical as yet. However, we can run a self consistent simulation of the earth's bow shock using the plasma and field results at the shock surface in the MHD simulation to determine the upstream and downstream boundary conditions on the hybrid code. By continually updating the data from the MHD code, we can run an accurate hybrid simulation of the shock structure, which is well known to depend strongly on the orientation of the IMF and flow mach number.
The hybrid code has been optimized for the SP-2 and will be run at the Ohio Supercomputing Center.
We propose to import continuously the results of both codes as well as the WIND data for display in the MetaCenter exhibit at SC'95 using two or more SGI Onyxes or equivalents to render the results in various ways. For the MHD results, these will include streamlines of the magnetic field, cut planes of plasma density and pressure, streamlines of electromagnetic flux entry and more. For the hybrid results, we will follow ion trajectories, show surfaces and vectors of electric and magnetic fields and more, superimposed on closeups of the MHD results. For the display we propose to use the NII/Wall.
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