Chromospheric Spectra of Small-scale Dynamic Features Observed on and off Solar Disk with Goode Solar Telescope

Abstract Our study of H α line profiles of rapid blue- and redshifted excursions measured with Goode Solar Telescope revealed an asymmetrical three-peak structure present in the blue wing of the H α line, suggesting complex internal velocity fields that may include bidirectional flows and transverse and torsional motions. Blueshifted plasma predominates across the field of view (FOV), correlating with higher temperatures (>10 4 K) and extending to greater heights. Conversely, redshifts are less spread over the FOV, are localized near network magnetic fields, and diminish rapidly with altitude. The frequency distribution associated with blueshifted events displays a bimodal structure with peaks centered at 7200 and 8800 K. The redshifted events display a much weaker and wide peak centered at about 9000 K. No significant difference in temperature distributions for blue- and redshifted events is observed in the range above 10,000 K. Variations of H α line profiles with height seem to indicate that the line-of-sight integration effects may be most significant within the 0–6 Mm layer above the photosphere, and it decreases with height.