Magnetic energy release and transients in the solar flare of 2000 July 14

High-resolution observations of a large solar flare on 2000 July 14 ("Basti lle Day Flare") from the Michelson Doppler Imager instrument on the SOHO sp acecraft reveal rapid variations of the magnetic field in the lower solar a tmosphere during the flare. Some of these variations were irreversible, occ urred in the vicinity of magnetic neutral lines, and likely were related to magnetic energy release in the flare. A surprising result is that these va riations happened very rapidly on the scale of 10-15 minutes in a large are a of similar to 50 Mm(2) at the beginning of the flare. Other, more localiz ed and impulsive magnetic field variations somewhat similar to "magnetic tr ansients" observed by Zirin and coworkers were accompanied by impulses in c ontinuum intensity and Doppler velocity. These impulses have dynamic charac teristics similar to Ellerman's "bombs" and Severny's "mustaches" and were probably caused by high-energy particles bombarding the solar surface.