Asymptotic Model for Large-Scale Quasiheliostrophic Flow

Starting from the ideal MHD equations written in spherical coordinates, using the regular perturbation method, quasiheliostrophic equations are derived as generalisation of quasigeostrophic models for atmospheric flow. From the fourth order momentum and induction equations, two prognostic equations for the stream function and magnetic flux function are derived. The magnetohydrodynamic model based on these equations is a suitable framework for describing the interaction between large-scale dynamic and magnetic features and the presence of specific patterns like active longitudes in the solar activity cycle.

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Formation of Coronal Holes and the Global Magnetic Field Distribution

International Astronomical Union Colloquium ◽

10.1017/s025292110002501x ◽

1994 ◽

Vol 144 ◽

pp. 65-67 ◽

Cited By ~ 1

Author(s):

V. Bumba ◽

M. Klvaňa ◽

V. Rušin ◽

M. Rybanský ◽

G. T. Buyukliev

Keyword(s):

Magnetic Fields ◽

Large Scale ◽

Coronal Holes ◽

Activity Cycle ◽

Close Relation ◽

Solar Activity Cycle ◽

Cycle Maximum ◽

Global Magnetic Field ◽

Mutual Relations ◽

The Individual

The photoelectric magnetograph of the Ondřejov Observatory was reconstructed in 1990 (Klvaňa and Bumba, 1994; Klvaňaet al, 1994). During 1991 and 1992, several hundred sets of measurements were obtained, mostly in line Fel 5253.47 Å. It has been found that some of the measurements are distributed very favorably around coronal holes, sometimes covering smaller parts and in a few cases even larger parts of their areas.Both 1991 and 1992 were exceptional as regards their relation to the phase of the ending solar activity cycle (No 22): while the period of the secondary cycle maximum (mainly the southern solar hemisphere) took place in 1991, the year 1992 coincided with the initial stage of its declining branch. Since the formation of coronal holes is in close relation to the dynamics of the global distribution of solar magnetic fields, we thought that before starting to investigate the detailed connections of the individual coronal holes with particular local magnetic fields, it might be interesting to study their mutual relations also on a large scale.

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Axially symmetric large-scale transport of the magnetic flux during solar activity cycle

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306001475 ◽

2006 ◽

Vol 2 (S233) ◽

pp. 71

Author(s):

Pavel Ambrož

Keyword(s):

Solar Activity ◽

Magnetic Flux ◽

Large Scale ◽

Activity Cycle ◽

Solar Activity Cycle ◽

Axially Symmetric

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Observed Large-Scale East-West Asymmetries in the Solar Corona

International Astronomical Union Colloquium ◽

10.1017/s0252921100025227 ◽

1994 ◽

Vol 144 ◽

pp. 151-154

Author(s):

J. C. Noëns ◽

B. Pech ◽

J. Xanthakis ◽

H. Mavromichalaki ◽

V. Tritakis ◽

...

Keyword(s):

Solar Activity ◽

Solar Corona ◽

Large Scale ◽

Activity Cycle ◽

Solar Activity Cycle ◽

Local Effects ◽

East And West ◽

East West

AbstractSome new results are presented and discussed about the problem of the asymmetries in the observed corona between the east and west limbs. “Local effects” are analysed. Relations within one eleven-year solar activity cycle are shown.

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Meridional component of the large-scale magnetic field at minimum and characteristics of the subsequent solar activity cycle

Astronomy Letters ◽

10.1134/s1063773717100061 ◽

2017 ◽

Vol 43 (10) ◽

pp. 697-702 ◽

Cited By ~ 1

Author(s):

V. N. Obridko ◽

B. D. Shelting

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Large Scale ◽

Activity Cycle ◽

Solar Activity Cycle ◽

Meridional Component ◽

Large Scale Magnetic Field

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The heliosphere and the Ulysses mission

Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences ◽

10.1098/rsta.1994.0127 ◽

1994 ◽

Vol 349 (1690) ◽

pp. 227-236 ◽

Cited By ~ 3

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Corona ◽

Coronal Hole ◽

High Speed ◽

Large Scale ◽

Activity Cycle ◽

Solar Activity Cycle ◽

Ecliptic Plane ◽

Sector Structure

The interplanetary medium consists primarily of the supersonic solar wind, carrying the frozen-in magnetic field extending from the solar corona. The properties of this medium are controlled by the state of the corona and by dynamic processes occurring in the medium itself. As a result, there are significant variations in those properties as a function of heliolatitude. In situ observations over the past three decades have been largely confined to the neighbourhood of the solar equatorial plane. While many of the important processes have been identified and studied extensively, observations are required as a function of heliolatitude to define large-scale structures and their dependence on processes in the solar corona. The Ulysses mission, launched in October 1990, is the first space probe dedicated to the exploration of the heliosphere out of the ecliptic plane. By January 1994, the spacecraft had reached a heliolatitude of 50° south. The first results of the mission are summarized here, including the evolution and disappearance of the interplanetary magnetic sector structure; the onset of the dominance of the high-speed solar wind stream originating in the expanding southern coronal hole; observations of the signatures of complex coronal mass ejections; the high-latitude structure of the heliospheric magnetic field, and the evolution of corotating interaction regions as a function of heliolatitude. In particular, the abrupt change in the rotation rate of the sector structure in mid-1992, followed by the equatorward extension of the southern polar coronal hole, represent new observations related to the evolution of large-scale coronal structures and solar magnetic fields and to processes controlling the solar activity cycle.

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

Geomagnetism and Aeronomy ◽

10.1134/s0016793220050047 ◽

2020 ◽

Vol 60 (5) ◽

pp. 586-596 ◽

Cited By ~ 1

Author(s):

A. D. Danilov ◽

A. V. Konstantinova

Keyword(s):

Solar Activity ◽

Activity Cycle ◽

Solar Activity Cycle

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The Solar Activity Cycle. I. Observations of the End of Cycle 22, 1993 September–1997 February

The Astrophysical Journal ◽

10.1086/305116 ◽

1998 ◽

Vol 493 (1) ◽

pp. 494-504 ◽

Cited By ~ 8

Author(s):

Jeffrey C. Hall ◽

G. W. Lockwood

Keyword(s):

Solar Activity ◽

Activity Cycle ◽

Solar Activity Cycle

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On the Prediction of Solar Cycles

Solar Physics ◽

10.1007/s11207-020-01760-7 ◽

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.

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