Observational Study of the Atmospheric Gravity Waves in the lower Solar Atmosphere

TL;DR

This study investigates atmospheric gravity and acoustic waves in the solar chromosphere using spectroscopic observations, revealing their propagation characteristics and association with magnetic flux regions and spicules.

Contribution

It provides new observational evidence of atmospheric gravity waves propagating along spicular structures in the solar chromosphere, highlighting their relation to magnetic fields.

Findings

Power of waves increases with height in the chromosphere.

AGWs are detected near magnetic flux concentrations and spicules.

AGWs propagate upward along spicular structures.

Abstract

The solar chromosphere exhibits a variety of waves originating from the photosphere and deeper layers, causing oscillations at different heights with distinct frequencies. This study identifies and analyze Atmospheric Gravity Waves (AGWs) and acoustic waves at various height pairs within the solar atmosphere utilising H$\alpha$, Ca II IR and Fe I 6173 A imaging spectroscopic observations from Swedish 1m Solar Telescope. We study and compare oscillations by analyzing power maps generated using velocities obtained from the filtergram difference and bisector methods. Our analysis shows a consistent increase in power with height in the solar chromosphere for both methods. In addition to this, our results show that AGWs are detected within or near magnetic flux concentration regions, where spicules are also predominant, exhibiting significant power in the chromosphere. These regions also feature inclined magnetic fields, which might be contributing to the propagation of these low-frequency AGWs in the chromosphere. Examining average power maps at spicule locations reveals significant power at AGWs frequency across different chromospheric heights. We speculate that these AGWs propagate upward along spicular structures and were not previously detected in the studies employing space-time map due to their limited lifetime. This study provides insights into the complex dynamics of solar chromospheric waves influenced by magnetic field, contributing to our understanding of AGWs and acoustic waves propagation across different layers of the solar atmosphere.