Synthetic observations of internal gravity waves in the solar atmosphere

TL;DR

This study uses realistic numerical simulations and synthetic spectral observations to analyze internal gravity waves in the solar atmosphere, revealing their signatures and energy flux characteristics.

Contribution

It introduces a method combining simulations and synthetic spectra to detect and analyze internal gravity waves, highlighting potential overestimations in energy flux measurements.

Findings

Signatures of IGWs are consistent with real Sun observations.

Phase differences vary with height and travel distance, affecting energy flux estimates.

Weak, less temperature-sensitive spectral lines are better for detecting IGWs.

Abstract

We study the properties of internal gravity waves (IGWs) detected in synthetic observations that are obtained from realistic numerical simulation of the solar atmosphere. We used four different simulations of the solar magneto-convection performed using the CO5BOLD code. A magnetic-field-free model and three magnetic models were simulated. The latter three models start with an initial vertical, homogeneous field of 10, 50, and 100 G magnetic flux density, representing different regions of the quiet solar surface. We used the NICOLE code to compute synthetic spectral maps from all the simulated models for the two magnetically insensitive neutral iron lines Fe I 5434 {\AA} and 5576 {\AA}. We find the signatures of the internal gravity waves in the synthetic spectra to be consistent with observations of the real Sun. The phase differences obtained using the spectral lines are significantly different from the phase differences in the simulation. The phase coherency between two atmospheric layers in the gravity wave regime is height dependent and is seen to decrease with the travel distance between the observed layers. We conclude that the energy flux of IGWs determined from the phase difference analysis may be overestimated by an order of magnitude. Spectral lines that are weak and less temperature sensitive may be better suited to detecting internal waves and accurately determining their energy flux in the solar atmosphere.