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

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.

scholarly journals The Solar Corona over the Recent Saros

1991 ◽  
Vol 130 ◽  
pp. 285-287 ◽  
Author(s):  
Jay M. Pasachoff
Keyword(s):  
Solar Activity ◽  
Solar Corona ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
The Sun ◽  
Scientific Value

AbstractWe are now at both the maximum of the solar activity cycle and at the most populated part of the saros. I discuss the solar corona over the recent saros and its changes with the solar activity cycle. We consider the scientific value of eclipse studies and how they relate to other ongoing coronal studies on the sun and other stars.

The heliosphere and the Ulysses mission

1994 ◽  
Vol 349 (1690) ◽  
pp. 227-236 ◽  
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.

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.

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