scholarly journals They do change after all: 25 yr of GONG data reveal variation of p-mode energy supply rates

2020 ◽  
Vol 500 (3) ◽  
pp. 3095-3110
Author(s):  
René Kiefer ◽  
Anne-Marie Broomhall
Keyword(s):  
Solar Activity ◽  
Energy Supply ◽  
Low Frequency ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Magnetic Activity ◽  
Temporal Behaviour ◽  
Global Oscillation Network Group ◽  
Parameter Ranges ◽  
Mode Energy

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 = 0–150 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 anticorrelated with the level of solar activity, for which we use the F10.7 index as a proxy. Modes of different mode frequency and harmonic degrees show varying strengths of anticorrelation with the F10.7 index, reaching as low as r = −0.82 for low frequency modes with l = 101–150. 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.

Solar-Cycle variation in the photospheric mean velocity flows: GONG observations

2018 ◽  
Vol 13 (S340) ◽  
pp. 59-60
Author(s):  
Brajesh Kumar
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Solar Disk ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Doppler Imaging ◽  
The Sun ◽  
Mean Velocity ◽  
Solar Cycle Variation ◽  
Global Oscillation Network Group

AbstractThe solar oscillation frequencies have shown variation over the solar activity cycle, which is believed to be the indicator of the structural and magnetic changes taking place in the Sun. The ground-based network of six identical solar telescopes in the Global Oscillation Network Group (GONG) program has been nearly-continuously observing the Sun since the last quarter of the year 1995 for Doppler imaging of the solar-disk aimed to study the oscillations and velocity flows on the surface of the Sun. In this work, we study the variations in the solar disk-integrated mean velocity flows on the solar surface as observed with the GONG over the complete Solar Cycle 23 and ongoing Cycle 24. The correlation analysis of these solar photospheric mean velocity flows relative to the various solar activity indicators is also discussed.

scholarly journals Solar-cycle irradiance variations over the last four billion years

2020 ◽  
Vol 636 ◽  
pp. A83 ◽  
Author(s):  
Anna V. Shapiro ◽  
Alexander I. Shapiro ◽  
Laurent Gizon ◽  
Natalie A. Krivova ◽  
Sami K. Solanki
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Solar Irradiance ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Magnetic Activity ◽  
The Sun ◽  
Earth’S Atmosphere ◽  
Solar Magnetic Activity ◽  
Earth's Atmosphere

Context. The variability of the spectral solar irradiance (SSI) over the course of the 11-year solar cycle is one of the manifestations of solar magnetic activity. There is strong evidence that the SSI variability has an effect on the Earth’s atmosphere. The faster rotation of the Sun in the past lead to a more vigorous action of solar dynamo and thus potentially to larger amplitude of the SSI variability on the timescale of the solar activity cycle. This could lead to a stronger response of the Earth’s atmosphere as well as other solar system planets’ atmospheres to the solar activity cycle. Aims. We calculate the amplitude of the SSI and total solar irradiance (TSI) variability over the course of the solar activity cycle as a function of solar age. Methods. We employed the relationship between the stellar magnetic activity and the age based on observations of solar twins. Using this relation, we reconstructed solar magnetic activity and the corresponding solar disk area coverages by magnetic features (i.e., spots and faculae) over the last four billion years. These disk coverages were then used to calculate the amplitude of the solar-cycle SSI variability as a function of wavelength and solar age. Results. Our calculations show that the young Sun was significantly more variable than the present Sun. The amplitude of the solar-cycle TSI variability of the 600 Myr old Sun was about ten times larger than that of the present Sun. Furthermore, the variability of the young Sun was spot-dominated (the Sun being brighter at the activity minimum than in the maximum), that is, the Sun was overall brighter at activity minima than at maxima. The amplitude of the TSI variability decreased with solar age until it reached a minimum value at 2.8 Gyr. After this point, the TSI variability is faculae-dominated (the Sun is brighter at the activity maximum) and its amplitude increases with age.

Trends in Parameters of the F2 Layer and the 24th Solar-Activity Cycle

2020 ◽  
Vol 60 (5) ◽  
pp. 586-596 ◽  
Author(s):  
A. D. Danilov ◽  
A. V. Konstantinova
Keyword(s):  
Solar Activity ◽  
Activity Cycle ◽  
Solar Activity Cycle

scholarly journals On the Prediction of Solar Cycles

Solar Physics ◽  
2021 ◽  
Vol 296 (1) ◽  
Author(s):  
V. Courtillot ◽  
F. Lopes ◽  
J. L. Le Mouël
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Transfer Function ◽  
Singular Spectrum Analysis ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Planetary Motion ◽  
Data Sets ◽  
Solar Cycles ◽  
Jovian Planets

AbstractThis article deals with the prediction of the upcoming solar activity cycle, Solar Cycle 25. We propose that astronomical ephemeris, specifically taken from the catalogs of aphelia of the four Jovian planets, could be drivers of variations in solar activity, represented by the series of sunspot numbers (SSN) from 1749 to 2020. We use singular spectrum analysis (SSA) to associate components with similar periods in the ephemeris and SSN. We determine the transfer function between the two data sets. We improve the match in successive steps: first with Jupiter only, then with the four Jovian planets and finally including commensurable periods of pairs and pairs of pairs of the Jovian planets (following Mörth and Schlamminger in Planetary Motion, Sunspots and Climate, Solar-Terrestrial Influences on Weather and Climate, 193, 1979). The transfer function can be applied to the ephemeris to predict future cycles. We test this with success using the “hindcast prediction” of Solar Cycles 21 to 24, using only data preceding these cycles, and by analyzing separately two 130 and 140 year-long halves of the original series. We conclude with a prediction of Solar Cycle 25 that can be compared to a dozen predictions by other authors: the maximum would occur in 2026.2 (± 1 yr) and reach an amplitude of 97.6 (± 7.8), similar to that of Solar Cycle 24, therefore sketching a new “Modern minimum”, following the Dalton and Gleissberg minima.

scholarly journals Helioseismic inferences

2009 ◽  
Vol 5 (S264) ◽  
pp. 33-38
Author(s):  
Hiromoto Shibahashi
Keyword(s):  
Solar Activity ◽  
Linear Approximation ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Convective Zone ◽  
Dynamo Model ◽  
Kinematic Dynamo ◽  
Wide Range ◽  
Dynamo Mechanism ◽  
Solar Type

AbstractThe brilliant outcome of some 30 years of helioseismology spreads over a wide range of topics. Some highlights relevant to the cause of the solar activity cycle are listed up. The rotation profile in the solar convective zone is discussed as an important source of the dynamo mechanism. The kinematic dynamo model is described in the linear approximation, and the condition for the solar type dynamo is derived. It is shown that comparison of this condition with the rotation profile determined from helioseismology is useful to identify the possible seats of the dynamo.

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