Variations in Dominant Wave Period in the Solar Atmosphere

TL;DR

This study investigates how the dominant wave period varies with height in the solar atmosphere, combining observational data from IRIS with numerical simulations to reveal a decreasing trend of the dominant period with altitude.

Contribution

It provides new observational evidence and numerical modeling of the height-dependent variation of dominant wave periods in the solar atmosphere.

Findings

Dominant wave period decreases with height in the solar atmosphere.

Wave period range varies within the spectrum at different heights.

Numerical simulations agree with observational results.

Abstract

Waves are an integral part of the solar atmosphere, and their characteristics (e.g., dominant period, range of periods, power, and phase angle) change on a diverse spatio-temporal scale. It is well well-established observationally that the dominant periods of solar oscillations are 5-min and 3-min in the photosphere and chromosphere, respectively. This shows that the wave spectra and their dominant periods evolve between these two layers. We present observational results that demonstrate variations of the dominant period with heights in the photosphere and chromosphere. Six photospheric absorption lines and one chromospheric line are analyzed by using the IRIS data, and the Doppler velocity time series at seven different atmospheric heights are determined. The wavelet analysis is applied to these time series, and the resulting spectrum of wave periods and its dominant period are deduced at these heights, which gives height variations of the dominant period. The obtained data shows that the dominant period decreases with height, and that there are also changes in the range of wave periods within the spectrum. Numerical simulations of filtered wave spectra through the solar atmosphere are also performed, and the obtained results match the observational data.