scholarly journals The heliosphere mass variations: 1996–2006

2008 ◽  
Vol 4 (S257) ◽  
pp. 291-293
Author(s):  
T. Pintér ◽  
I. Dorotovič ◽  
M. Rybanský
Keyword(s):  
Solar Activity ◽  
Total Mass ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Ecliptic Plane ◽  
Polar Regions ◽  
Specific Mass ◽  
23Rd Solar Cycle ◽  
23Rd Cycle

AbstractThe variations of the global mass of heliosphere in the 23rd cycle of the solar activity are described. The results are derived from solar corona observations and from ‘in situ’ measurements made by the space probes SOHO, VOYAGER2, ACE, WIND, and ULYSSES. It has been revealed that though the total mass of corona fluctuates during the solar activity cycle approximately in a ratio of 1 : 3, the specific mass flow (q) in the solar wind does not change in the ecliptic plane. In the polar regions the q decreases during the minimum in a third of the original value and the velocity of expansion is roughly double. These findings are valid for the 23rd solar cycle.

Positional evolution of magnetic foci in the polar regions of the Sun with the phase of the solar activity cycle

2006 ◽  
Vol 50 (10) ◽  
pp. 834-841 ◽  
Author(s):  
D. V. Klepikov ◽  
B. P. Filippov ◽  
A. Ajabshirizadeh ◽  
Yu. V. Platov
Keyword(s):  
Solar Activity ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Polar Regions ◽  
The Sun

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 The Solar Orbiter Science Activity Plan

2020 ◽  
Vol 642 ◽  
pp. A3 ◽  
Author(s):  
I. Zouganelis ◽  
A. De Groof ◽  
A. P. Walsh ◽  
D. R. Williams ◽  
D. Müller ◽  
...  
Keyword(s):  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Coronal Magnetic Field ◽  
Space Mission ◽  
The Sun ◽  
Particle Radiation ◽  
Science Activity ◽  
Science Operations ◽  
Solar Eruptions

Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate?; (2) How do solar transients drive heliospheric variability?; (3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?; (4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? Maximising the mission’s science return requires considering the characteristics of each orbit, including the relative position of the spacecraft to Earth (affecting downlink rates), trajectory events (such as gravitational assist manoeuvres), and the phase of the solar activity cycle. Furthermore, since each orbit’s science telemetry will be downloaded over the course of the following orbit, science operations must be planned at mission level, rather than at the level of individual orbits. It is important to explore the way in which those science questions are translated into an actual plan of observations that fits into the mission, thus ensuring that no opportunities are missed. First, the overarching goals are broken down into specific, answerable questions along with the required observations and the so-called Science Activity Plan (SAP) is developed to achieve this. The SAP groups objectives that require similar observations into Solar Orbiter Observing Plans, resulting in a strategic, top-level view of the optimal opportunities for science observations during the mission lifetime. This allows for all four mission goals to be addressed. In this paper, we introduce Solar Orbiter’s SAP through a series of examples and the strategy being followed.

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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