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.

scholarly journals Forecasting the solar activity cycle: new insights

2012 ◽  
Vol 8 (S294) ◽  
pp. 439-444 ◽  
Author(s):  
Dibyendu Nandy ◽  
Bidya Binay Karak
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Solar Interior ◽  
Solar Dynamo ◽  
Term Prediction ◽  
Dynamo Mechanism ◽  
Short Term Prediction ◽  
Long Term Prediction

AbstractHaving advance knowledge of solar activity is important because the Sun's magnetic output governs space weather and impacts technologies reliant on space. However, the irregular nature of the solar cycle makes solar activity predictions a challenging task. This is best achieved through appropriately constrained solar dynamo simulations and as such the first step towards predictions is to understand the underlying physics of the solar dynamo mechanism. In Babcock-Leighton type dynamo models, the poloidal field is generated near the solar surface whereas the toroidal field is generated in the solar interior. Therefore a finite time is necessary for the coupling of the spatially segregated source layers of the dynamo. This time delay introduces a memory in the dynamo mechanism which allows forecasting of future solar activity. Here we discuss how this forecasting ability of the solar cycle is affected by downward turbulent pumping of magnetic flux. With significant turbulent pumping the memory of the dynamo is severely degraded and thus long term prediction of the solar cycle is not possible; only a short term prediction of the next cycle peak may be possible based on observational data assimilation at the previous cycle minimum.

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.

MEDIUM-TERM OSCILLATIONS OF THE SOLAR ACTIVITY

2021 ◽  
Vol 44 ◽  
pp. 85-91
Author(s):  
V.N. Obridko ◽  
◽  
D.D. Sokoloff ◽  
V.V. Pipin ◽  
A.S. Shibalova ◽  
...  
Keyword(s):  
Solar Activity ◽  
Activity Cycle ◽  
Solar Interior ◽  
Local Fields ◽  
Lower Atmosphere ◽  
High Solar Activity ◽  
Dynamo Model ◽  
Sunspot Activity ◽  
Geomagnetic Variations ◽  
Near Surface

In addition to the well-known 11-year cycle, longer and shorter characteristic periods can be isolated in variations of the parameters of helio-geophysical activity. Periods of about 36 and 60 years were revealed in variations of the geomagnetic activity and an approximately 60-year periodicity, in the evolution of correlation between the pressure in the lower atmosphere and the solar activity. Similar periods are observed in the cyclonic activity. Such periods in the parameters of the solar activity are difficult to identify because of a limited database available; however, they are clearly visible in variations of the asymmetry of the sunspot activity in the northern and southern solar hemispheres. In geomagnetic variations, one can also isolate oscillations with the characteristic periods of 5-6 years (QSO) and 2-3 years (QBO). We have considered 5-6-year periodicities (about half the main cycle) observed in variations of the sunspot numbers and the intensity of the dipole component of the solar magnetic field. A comparison with different magnetic dynamo models allowed us to determine the possible origin of these oscillations. A similar result can be reproduced in a dynamo model with nonlinear parameter variations. In this case, the activity cycle turns out to be anharmonic and contains other periodicities in addition to the main one. As a result of the study, we conclude that the 5-6-year activity variations are related to the processes of nonlinear saturation of the dynamo in the solar interior. Quasi-biennial oscillations are actually separate pulses related little to each other. Therefore, the methods of the spectral analysis do not reveal them over large time intervals. They are a direct product of local fields, are generated in the near-surface layers, and are reliably recorded only in the epochs of high solar activity.

Sign in / Sign up

Export Citation Format

Share Document