They Do Change After All: 25 Years of GONG Data Reveal Variation of p-Mode Energy Supply Rates

TL;DR

This study demonstrates that solar p-mode energy supply rates vary with the solar activity cycle, showing a strong anti-correlation with the $F_{10.7}$ index, based on analysis of two Schwabe cycles using GONG data.

Contribution

First detailed analysis of p-mode energy supply rates over solar cycles using GONG data, revealing their variation and anti-correlation with solar activity levels.

Findings

Energy supply rates are anti-correlated with solar activity.

Varying anti-correlation strength across different mode frequencies and degrees.

Provides comprehensive tables of energy supply rates for individual modes.

Abstract

It has been shown over and over again that the parameters of solar p modes vary through the solar activity cycle: frequencies, amplitudes, lifetimes, energies. However, so far, the rates at which energy is supplied to the p modes have not been detected to be sensitive to the level of magnetic activity. We set out to re-inspect their temporal behaviour over the course of the last two Schwabe cycles. For this, we use Global Oscillation Network Group (GONG) p-mode parameter tables. We analyse the energy supply rates for modes of harmonic degrees $l=0\text{-}150$ and average over the azimuthal orders and, subsequently, over modes in different parameter ranges. This averaging greatly helps in reducing the noise in the data.We find that energy supply rates are anti-correlated with the level of solar activity, for which we use the $F_{10.7}$ index as a proxy. Modes of different mode frequency and harmonic degrees show varying strengths of anti-correlation with the $F_{10.7}$ index, reaching as low as $r=-0.82$ for low frequency modes with $l=101\text{-}150$. In this first dedicated study of solar p-mode energy supply rates in GONG data, we find that they do indeed vary through the solar cycle. Earlier investigations with data from other instruments were hindered by being limited to low harmonic degrees or by the data sets being too short. We provide tables of time-averaged energy supply rates for individual modes as well as for averages over disjunct frequency bins.