Temporal Variations of High-Degree Solar p-Modes from GONG and MDI

TL;DR

This study analyzes how high-degree solar p-mode amplitudes and widths vary over time during the solar cycle, using GONG+ and MDI data, revealing cycle-dependent trends and long-term variations.

Contribution

It provides a comparative analysis of high-degree p-mode parameter variations from GONG+ and MDI data during solar cycle 23's declining phase, highlighting cycle trends and long-term changes.

Findings

Amplitudes increase and line-widths decrease during the declining phase of cycle 23.

Similar trends are observed in quiet-Sun regions but with reduced magnitude.

GONG+ data show additional long-term variations beyond the solar cycle trend.

Abstract

We study temporal variations in the amplitudes and widths of high-degree acoustic modes in the quiet and active Sun by applying ring-diagram technique to the GONG+ and MDI Dopplergrams during the declining phase of cycle 23. The increase in amplitudes and decrease in line-widths in the declining phase of the solar activity is in agreement with previous studies. A similar solar cycle trend in the mode parameters is also seen in the quiet-Sun regions but with a reduced magnitude. Moreover, the amplitudes obtained from GONG+ data show long-term variations on top of the solar cycle trend.