Magnetic Energy Release during the 2002 September 9 Solar Flare

We study the magnetic energy release during the 2002 September 9 flare using the high-cadence (40 ms) Hα filtergram at Big Bear Solar Observatory (BBSO), along with hard X-ray and microwave data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Owens Valley Solar Array (OVSA), respectively. We take the Poynting vector approach with the standard two-dimensional geometry of the reconnecting current sheet (RCS) but suggest a new technique to infer the area of the RCS, in order to complete the magnetic energy calculation entirely with observed quantities. We found five peaks of impulsive magnetic energy release, concentrated within 10-30 s periods, that are episodic with the peaks of the hard X-ray light curve. The maximum amount of energy released per peak reaches ~2.6 × 1030 ergs s-1, and the electron energy deposition rate derived from the RHESSI spectra falls into the range of 10%-80% of the magnetic energy release rate. We briefly discuss this result in comparison with other studies thus far made toward understanding of the magnetic reconnection in solar flares and suggest the pulsating current sheet model as the most plausible interpretation of our result.