Utilizing CISM MHD Results in SEP Modeling S. A. Ledvina, D. Odstrcil, J. G. Luhmann, D. Krauss-Varban, and I. Roth

What the SEP simulations need from the MHD results The shock location The shock strength, M A,  The shock normal angle  Bn The MHD variables –Density –Temperature –Magnetic field –Velocity

The SEP code uses the guiding center approximation: We only need to store the MHD variable along the magnetic field lines that originates from the Earth and traces back to the Sun. Since this is the only field line we need we can save the MHD values along this line often (~5 minutes).

To meet these requirements we have added a field line tracing output routine to ENLIL

Finding the Shock Normalize the dynamic pressure by r 2. Calculate the gradients in the normalized pressure.

Finding the Shock Cont. Calculate the gradient of the normalized pressure along the field line. Starting from the Earth find the largest magnitude of the gradient. That is the shock location. Find where the gradients change by some value (~20%) from the background. Use the values midway between these points to find: –Shock strength –Shock jump conditions Gradient along field line

Finding the shock normal angle Minimum variance analysis?

Remaining Code Issues Adding a field line tracing output routine to MAS Tracing field lines across the MAS- ENLIL boundary Tracing field lines across processors in parallel computations Model Interface