Investigating chromospheric dynamics as a solar forecasting tool.

摘要

The observational goal of this work was to seek and relate aspects of chromospheric and photospheric motions to the emergence and shearing of the non-potential magnetic fields that lead to solar flares and to verify anecdotal evidence that a localized increase in the curl of the horizontal flow (vorticity) in Halpha images indicates the imminent onset of solar flares in an active region, to extend this to three-dimensional flows by including line-of-site (LOS) velocities, and to evaluate this as a tool to forecast solar flare onset. Filament brightenings were observed in NOAA 0085 on August 22, 2002, with the Dunn Solar Telescope (DST) at Sacramento Peak, NM. These high-resolution data include four-second-cadence g-band and Halpha images, and 104-second-cadence Ca I and Halpha Doppler-grams. The observed activity was limited to filament brightening with a few small bright points exceeding four times the background intensity. Horizontal motions in the photosphere and chromosphere were determined by local correlation tracking of g-band and Halpha images, respectively. LOS velocities in the photosphere and chromosphere were determined by Doppler shifts of Ca I and Halpha line profiles, respectively, using the center-of-gravity method.; Analysis of data collected for this research identified defective equipment in use on the DST and weakness in DST operating/observing procedures. This dissertation makes recommendations for corrective actions to prevent many of the problems encountered during observing runs for this research and recommends procedures for students at the National Solar Observatory to assist with the maintenance and calibration of the equipment. This work presents an improved technique for producing flatfields to gain correct data. The method is shown to reduce error in the flatfield by 50 percent and indicates greater reductions in this error are possible while reducing the time required to produce the flatfield.; This research found no indication of an increase in the curl of the horizontal flow preceding the observed brightenings, but showed the increase in the curl correlated with the onset of the brightenings, indicating the correlation-tracking algorithm was tracking on the brightening features and not on actual plasma motions. Additionally, an active filament showed strong vorticity signatures with no brightening occurring through this period, identifying a weakness of the vorticity signature as a flare-forecasting tool.