Using Ideal Electric Fields Estimated from Vector Magnetogram Sequences to Drive Coronal MHD Simulations
Abstract
Dynamic models of the coronal magnetic field show promise as space weather forecasting tools. Such models should be driven by electric fields derived from sequences of photospheric vector magnetograms, the only routine measurements of the solar magnetic field currently available. Previous studies derived flows --- or, equivalently, ideal electric fields --- consistent with evolution of the normal photospheric field, which could be used in "component driving" of an MHD model, i.e., enforcing consistent evolution of the observed and modeled normal magnetic fields. In this extension of the component-driving approach, we demonstrate how to derive ideal electric fields consistent with the observed evolution of both the normal and horizontal magnetic field, useful for "vector driving," i.e., enforcing consistency between all three components of the observed and model photospheric magnetic vectors. To drive an MHD model, this "ideal vector driving" (IVD) approach amount to specification of both the velocity (perpendicular the magnetic field) and its vertical derivative at the model's bottom boundary. The IVD method can incorporate results from local/ tracking methods (e.g., LCT or DAVE) and/or results from global methods (e.g., MEF or poloidal-toroidal decomposition [PTD]). We have applied this new approach to "synthetic magnetograms" extracted from MHD simulations (where the magnetic and electric fields are exactly known), as well as to a four-hour sequence of vector magnetograms from NOAA AR 8210, on 01 May 1998, just prior to an M-class flare and geoeffective CME.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2008
- Bibcode:
- 2008AGUSMSH54A..04W
- Keywords:
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- 7509 Corona;
- 7513 Coronal mass ejections (2101);
- 7524 Magnetic fields;
- 7529 Photosphere;
- 7833 Mathematical and numerical techniques (0500;
- 3200)