Solar magnetic reconnection viewed with TRACE and SOHO/MDI

We combine high-resolution, high-cadence images from the Transition Region and Coronal Explorer (TRACE) with high quality line-of-sight magnetograms from the Michelson Doppler Imager (MDI) on SOHO to examine signatures of solar magnetic reconnection and attempt to infer associated physical parameters. We estimate the coronal magnetic reconnection rate from the change in the photospheric magnetic flux swept out by the evolving flare ribbons. For the first event studied - a two-ribbon, GOES M1 class flare from NOAA active region 9236 near central meridian on 2000 Nov 23 23:28 UT - we found that the reconnection appeared to be fast, with the inferred inflow velocity a significant fraction of the Alfvén velocity, assuming standard coronal parameters and a simple geometry for the reconnecting region. We consider other events and use (a) coronal imaging of the reconnection region (as available from TRACE, the SOHO/EUV Imaging Telescope, or the Yohkoh/Soft Xray Telescope), (b) extrapolation of the photospheric magnetograms, and (c) correlative studies of the reconnection rates with ribbon intensities, to check our assumptions and assess the uncertainties of our results. This work is supported by NASA contracts NAG5-10483 (MDI) and NAS5-38099 (TRACE).