Numerical Simulations of Magnetoacoustic-Gravity Waves in the Solar Atmosphere

TL;DR

This study uses numerical simulations to explore how localized pressure and velocity pulses generate magnetoacoustic-gravity waves in the solar atmosphere, revealing wave reflection, trapping, and plasma dynamics influenced by magnetic field configurations.

Contribution

It introduces a realistic 2D MHD simulation of magnetoacoustic-gravity waves in the solar atmosphere with different magnetic field orientations, demonstrating wave excitation, reflection, and trapping mechanisms.

Findings

Small pulses can generate magnetoacoustic-gravity waves.

Waves are reflected from the transition region due to temperature gradients.

Atmospheric cavities can act as resonators for oscillations.

Abstract

We investigate the excitation of magnetoacoustic-gravity waves generated from localized pulses in the gas pressure as well as in vertical component of velocity. These pulses are initially launched at the top of the solar photosphere that is permeated by a weak magnetic field. We investigate three different configurations of the background magnetic field lines: horizontal, vertical and oblique to the gravitational force. We numerically model magnetoacoustic-gravity waves by implementing a realistic (VAL-C) model of solar temperature. We solve two-dimensional ideal magnetohydrodynamic equations numerically with the use of the FLASH code to simulate the dynamics of the lower solar atmosphere. The initial pulses result in shocks at higher altitudes. Our numerical simulations reveal that a small-amplitude initial pulse can produce magnetoacoustic-gravity waves, which are later reflected from the transition region due to the large temperature gradient. The atmospheric cavities in the lower solar atmosphere are found to be the ideal places that may act as a resonator for various oscillations, including their trapping and leakage into the higher atmosphere. Our numerical simulations successfully model the excitation of such wave modes, their reflection and trapping, as well as the associated plasma dynamics.