ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation O
tokens: density in this domain becomes comparable to the previously introduced offset. Finally, the most interesting result revealed by these plots is that during phase 2 the velocity profiles are most often located very close together and are, moreover, in a good correspondence with the macrospicules’ leading edge trajectories (black line in Fig. 8 ) discussed in the next section. Fig. 7 Reconstructed evolution of the macrospicule’s one-dimensional velocity field as projected on the vertical axis. Upward velocities are shown in blue and downward in red. Fig. 8 Velocity profiles at varied heights from 15 to 40 Mm (coloured lines). The straight black line corresponds to the parabolic fit of the macrospicule’s leading edge trajectory. Table 1 Obtained parameters of the macrospicules. Notes. Here, deceleration is the actual value measured from the parabolic fit, while ballistic deceleration is calculated based on Eq. ( 13 ). Beyond that, for one of the macrospicules (No. 10 in Table 1 , which was chosen for illustration in Figs. 4 – 8 , and 10 ) we identified a train of three compression waves which start to propagate upwards from the macrospicule’s base in the early phase of its motion. The waves are scarcely seen in the initial density map, but are clearly identifiable in the subtracted high-frequency component (Fig. 5 c) as a set of fringes. They arise mainly from intensity variations, and we are inclined to interpret them as the magneto-acoustic waves since the intensity change is more likely to result from the density oscillations, rather than from a change in temperature or in ionisation degree. The inclination of the fringes and the distance between them yields a varying propagation velocity, which gradually decreases from km s for the first wave to km s for the last one, and a wave period of roughly s. Most probably, the leftovers of these waves in the filtered density map are responsible for the quasi-periodic disturbances in the velocity field, seen in Fig. 8 at , , and min. 3.2. Leading edge trajectories Along with the reconstruction of the velocity field, we studied trajectories of the apparent end points of the same 18 macrospicules, and for 15 of them we found these points to follow parabolic trajectories with high precision (Fig. 4 d). The obtained trajectory parameters corrected for the inclination angle are presented in Table 1 . The decelerations typically range from 160 to 230 m s and initial velocities (defined as the extrapolated velocity at zero height) from 80 to 130 km s. Two macrospicules, however (Nos. 2 and 4), have significantly higher decelerations, which are even larger than gravity on the solar surface m s, and correspondingly have significantly higher initial velocities. Also, the maximum heights reached by the macrospicules are typically from 30 to 45 Mm, and the lifetimes are in the range of 10–20 min, which is in a good agreement with earlier studies ( Withbroe et al. 1976 ; Dere et al. 1989 ; Karovska Habbal 1994 ).