Reflection and Conversion of Magneto-Gravity Waves in the Solar Chromosphere: Windows to the Upper Atmosphere

TL;DR

This paper investigates how magneto-gravity waves propagate, reflect, and convert in the solar chromosphere, revealing conditions under which they can transfer energy upward, potentially impacting solar atmospheric heating.

Contribution

It provides a detailed analysis of wave mode conversion and reflection in the solar chromosphere, highlighting the role of magnetic field orientation in energy transfer processes.

Findings

Weak magnetic fields reflect gravity waves downward as slow magnetoacoustic waves.

Certain magnetic orientations allow gravity waves to convert into Alfven and acoustic waves.

Wave energy fluxes can match chromospheric radiative losses.

Abstract

The detection of upward propagating internal gravity waves at the base of the Sun's chromosphere has recently been reported by Straus et al., who postulated that these may efficiently couple to Alfven waves in magnetic regions. This may be important in transporting energy to higher levels. Here we explore the propagation, reflection and mode conversion of linear gravity waves in a VAL C atmosphere, and find that even weak magnetic fields usually reflect gravity waves back downward as slow magnetoacoustic waves well before they reach the Alfven/acoustic equipartition height at which mode conversion might occur. However, for certain highly inclined magnetic field orientations in which the gravity waves manage to penetrate near or through the equipartition level, there can be substantial conversion to either or both upgoing Alfven and acoustic waves. Wave energy fluxes comparable to the chromospheric radiative losses are expected.