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We report a series of numerical experiments for the propagation of a momentum pulse representing a chromospheric jet, simulated using an idealized magnetohydrodynamic model. The jet in a stratified lower solar atmosphere is subjected to a varied initial driver (amplitude, period) and magnetic field conditions to examine the parameter influence over jet morphology and kinematics. The simulated jet captured key observed spicule characteristics including maximum heights, field-aligned mass motions/trajectories, and cross-sectional width deformations. Next, the jet features also show a prominent bright, bulb-like apex, similar to reported observed chromospheric jets, formed due to the higher density of plasma and/or waves. Furthermore, the simulations highlight the presence of not yet observed internal crisscross/knots substructures generated by shock waves reflected within the jet structure. Therefore we suggest verifying these predicted fine-scale structures in highly localized lower solar atmospheric jets, e.g., in spicules or fibrils by high-resolution observations, offered by the Daniel K. Inoyue Solar Telescope or otherwise.

An Extreme Ultraviolet (EUV) jet that occurred around 22:30 on July 2, 2012 was observed by the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory (SDO). There were two phases of the jet. In Phase 1, two blobs were observed. In Phase 2, the intensity of the jet was almost coherent initially. One minute later, three blobs were formed at the same time in the jet, and the width of the jet changed after the formation of these blobs. The formation and evolution processes of the blobs in these two phases are analyzed in this paper. The physical parameters of the blobs are determined. The measured width of the blobs is 0.8 − 2.3 Mm, and the apparent velocities of the blobs are from 59 km s−1 to 185 km s−1. The formation mechanism of the blobs is likely to be tear-mode instability.

We report the first observational detection of frequency modulation in the cross-sectional width of spicule structures due to field-aligned plasma flows. Cross-sectional width variations were estimated for the least superimposed off-limb spicules observed in high-resolution Hα imaging spectroscopy data. Analysis of estimated cross-sectional widths suggest periodic oscillations, concurrent with 2D numerical modeling for a jet structure in a stratified solar atmosphere. Spectral analysis for both observed and simulated cross-sectional widths indicate frequency modulation as noticeable shifts in estimated periodicities during rise and fall phases of field-aligned plasma flows in the jet structure. Furthermore, the presence of the first overtone in a dynamic/spicular waveguide is also evident in both the observed and the simulated jet structures. These harmonics can be an important tool for future chromospheric magnetoseismology investigations and applications to dynamic waveguides (like spicules).

We report on numerical simulations of a propagating momentum pulse, representing an inclined jet structure in a stratified lower solar atmosphere model. Here, the numerical jets were generated via injection of a momentum pulse misaligned with the radial magnetic field, which resulted in a collimated structure that mimicked the observed inclined jet features in the chromosphere. The influence of inclination angle was examined for a variety of initial driver conditions (amplitude, period) and magnetic field magnitudes to identify their potential role in determining the morphological and dynamical characteristics of chromospheric jets. The numerical jets in our computational domain were consistent with the observed magnitudes of apex height and cross-sectional width for average inclination of chromospheric features. Furthermore, with an increasing misalignment between the momentum pulse and ambient magnetic field, the simulated structures showed a drop in the maximum apex height and length, while an increase in cross-sectional width magnitudes. Our numerical experiments also revealed the development of a pulse-like transverse motions in jets along with high density edges/nodes in the direction of jet displacement. It is postulated that dynamic kink instability might be responsible for the observed kinematic behavior of the inclined jet structures in the solar chromosphere.