CISM

SOHO image animation (57k)
images from SOHO-EIT

Solar/Interplanetary Models
active regions

Disappearance or disruption of a filament or prominence observed in ultraviolet images of the Sun is used by forecasters as a CME occurrence proxy. The NRL 3-D MHD mesoscale model examines the connection between photospheric magnetic field evolution on active region scales and prominence evolution. Similarly, Berkeley/HAO models suggest the rapidly evolving, flaring active regions imaged with the SOHO MDI magnetograph are connected with the eruption of twisted, knotted flux tubes from beneath the photosphere. The mesoscale models can be embedded into the coronal models to simulate the reaction of the corona to active region-scale magnetic field evolution, revealing the connections between flares, prominences, and CMEs.

The top figure suggests how the evolving magnetic field looks around an erupting prominence, based on MDI images and a force-free field model. The field lines are superposed on an EUV image from the EIT on SOHO. The adjacent two figures show field lines from the NRL 3D mesoscale MHD models. One snapshot is of a prospective evolving prominence (red), driven by shearing a multipolar photospheric field (blue) along its neutral line. In the other panel, active region fields are shown merging into the fields of overlying and adjacent structures. The lower image is from HAO/Berkeley MHD simulations of kink-unstable flux tubes rising through the solar convection zone and into the photosphere, where they manifest themselves (according to a Berkeley/NRL model) as complex "delta" sunspots like those associated with major flares. The Berkeley/NRL/HAO modelers will work with SAIC to introduce key mesoscale effects into the global simulations.

Click on the top, bottom and middle right images to view the corresponding animation. Click on the middle left image to enlarge.

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