A Clock in the Sun?

2019 ◽  
Vol 15 (S354) ◽  
pp. 127-133
Author(s):  
C. T. Russell ◽  
J. G. Luhmann ◽  
L. K. Jian
Keyword(s):  
Sunspot Number ◽  
Solar Minimum ◽  
Sunspot Cycle ◽  
Solar Dynamo ◽  
The Sun ◽  
Average Period ◽  
Magnetic Cycle ◽  
Number Cycle ◽  
As If

AbstractThe sunspot cycle is quite variable in duration and amplitude, yet in the long term, it seems to return to solar minimum on schedule, as if guided by a clock with an average period of close to 11.05 years for the sunspot number cycle and 22.1 years for the magnetic cycle. This paper provides a brief review of the sunspot number cycle since 1750, discusses some of the processes controlling the solar dynamo, and provides clues that may add to our understanding of what controls the cadence of the solar clock.

scholarly journals Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude

Solar Physics ◽  
2020 ◽  
Vol 295 (12) ◽  
Author(s):  
Scott W. McIntosh ◽  
Sandra Chapman ◽  
Robert J. Leamon ◽  
Ricky Egeland ◽  
Nicholas W. Watkins
Keyword(s):  
Solar Cycle ◽  
Sunspot Number ◽  
Sunspot Cycle ◽  
Periodic Variation ◽  
Magnetic Activity ◽  
The Sun ◽  
Magnetic Cycle ◽  
Hilbert Transforms ◽  
Observational Astronomy ◽  
Activity Cycles

AbstractThe Sun exhibits a well-observed modulation in the number of spots on its disk over a period of about 11 years. From the dawn of modern observational astronomy, sunspots have presented a challenge to understanding—their quasi-periodic variation in number, first noted 175 years ago, has stimulated community-wide interest to this day. A large number of techniques are able to explain the temporal landmarks, (geometric) shape, and amplitude of sunspot “cycles,” however, forecasting these features accurately in advance remains elusive. Recent observationally-motivated studies have illustrated a relationship between the Sun’s 22-year (Hale) magnetic cycle and the production of the sunspot cycle landmarks and patterns, but not the amplitude of the sunspot cycle. Using (discrete) Hilbert transforms on more than 270 years of (monthly) sunspot numbers we robustly identify the so-called “termination” events that mark the end of the previous 11-yr sunspot cycle, the enhancement/acceleration of the present cycle, and the end of 22-yr magnetic activity cycles. Using these we extract a relationship between the temporal spacing of terminators and the magnitude of sunspot cycles. Given this relationship and our prediction of a terminator event in 2020, we deduce that sunspot Solar Cycle 25 could have a magnitude that rivals the top few since records began. This outcome would be in stark contrast to the community consensus estimate of sunspot Solar Cycle 25 magnitude.

A long-term geophysical and astronomical dataset: sunspot counting from 1610 to 2021

2021 ◽  
Author(s):  
José M. Vaquero
Keyword(s):  
Solar Activity ◽  
19Th Century ◽  
Sunspot Number ◽  
Solar Physics ◽  
The Sun ◽  
Essential Factor ◽  
The Past ◽  
The 19Th Century ◽  
Made In

<p>Solar activity is an essential factor for the study of many aspects of the geophysical and astronomical sciences. A very simple measure of solar activity is counting sunspots using telescopes. This task can be done even with small telescopes since the Sun is apparently a very large and luminous star. For this reason, it is possible to rescue the ancient observations of sunspots made in the past centuries to obtain an image of the evolution of solar activity during the last four centuries.</p><p>The first attempt to reconstruct solar activity from these records was made by Rudolf Wolf, who defined the <em>Sunspot Number</em> index in the 19th century. The Zurich Observatory (and later the Brussels Observatory) was in charge of continuing Wolf's work to the present day. In 1998, Hoyt and Schatten presented a new reconstruction of solar activity that was very different from Wolf's reconstruction (Vaquero and Vázquez, 2009). Many of these differences were solved by Clette et al. (2014).</p><p>Currently, research to improve the <em>Sunspot Number</em> is focused on (i) improving the database by reviewing old observations, and (ii) improving the methodologies to convert raw data into the <em>Sunspot Number</em> index. In this work, we try to present the latest advances in this task (Muñoz-Jaramillo and Vaquero, 2019; Arlt and Vaquero, 2020).</p><p> </p><p>References</p><p>Arlt, R., Vaquero, J.M. (2020) Living Reviews in Solar Physics 17, 1.</p><p>Clette, F. et al. (2014) Space Science Reviews 186, 35.</p><p>Muñoz-Jaramillo, A., Vaquero, J.M. (2019) Nature Astronomy 3, 205.</p><p>Vaquero, J.M. and Vázquez, M. (2009) The Sun recorded through history (Springer).</p>

A Behavioural Model of the Solar Magnetic Cycle

2017 ◽  
Vol 13 (S335) ◽  
pp. 94-97
Author(s):  
Milton Munroe
Keyword(s):  
Magnetic Field ◽  
Conceptual Model ◽  
Differential Rotation ◽  
Toroidal Field ◽  
Solar Dynamo ◽  
The Sun ◽  
Poloidal Field ◽  
Magnetic Cycle ◽  
Poloidal Magnetic Field ◽  
Solar Magnetic Cycle

All recent models of solar magnetic cycle behaviour assume that the Ω-effect stretches an existing poloidal magnetic field into a toroidal field using differential rotation (Featherstone and Miesch 2015). The α-effect recycles the toroidal field back to a poloidal field by convection and rotation and this is repeated throughout the cycle. Computer simulations based on that conceptual model still leave many questions unanswered. It has not resolved where the solar dynamo is located, what it is or what causes the differential rotation which it takes for granted. Does this paradigm need changing? The conceptual model presented here examines the sun in horizontal sections, analyses its internal structure, presents new characterizations for the solar wind and structures found and shows how their interaction creates rotation, differential rotation, the solar dynamo and the magnetic cycle.

scholarly journals Variation of Even and Odd Parity in the Solar Dynamo

1990 ◽  
Vol 138 ◽  
pp. 379-382
Author(s):  
A. Brandenburg ◽  
R. Meinel ◽  
D. Moss ◽  
I. Tuominen
Keyword(s):  
Phase Space ◽  
Time Scale ◽  
Beat Frequency ◽  
The Sun ◽  
Magnetic Cycle ◽  
Secular Variations ◽  
Spot Number ◽  
Term Variation ◽  
Long Time

We have studied axisymmetric nonlinear αω-dynamo models taking the interaction between even and odd parities fully into account. It turns out that the dominating type of symmetry is not always determined uniquely, but it can vary on a very long time scale compared to the period of the magnetic cycle. In some cases the frequency of this long term variation is close to the beat frequency of the two solutions with purely dipolar and purely quadrupolar parity. The occurrence of a second frequency is typical of solutions whose trajectory describes a torus in the phase space. We argue that this finding is of relevance for understanding secular variations observed in the Sun. For example measurements of sunspots indicate that the spot number on the northern hemisphere at present exceeds the number on the southern hemisphere. The reverse seems to have been the case at the end of last century.

scholarly journals Joint Discussion 8 Solar and stellar activity cycles

2006 ◽  
Vol 2 (14) ◽  
pp. 271-272
Author(s):  
Alexander G. Kosovichev ◽  
Klaus G. Strassmeier
Keyword(s):  
Magnetic Field ◽  
Time Scales ◽  
Tree Ring ◽  
Solar Magnetic Field ◽  
Sunspot Cycle ◽  
Magnetic Cycle ◽  
Stellar Activity ◽  
Tree Ring Data ◽  
Activity Cycles

The solar magnetic field and its associated atmospheric activity exhibits periodic variations on a number of time scales. The 11-year sunspot cycle and its underlying 22-year magnetic cycle are, besides the 5-minute oscillation, the most widely known. Amplitudes and periods range from a few parts per million (ppm) and 2–3 minutes for p-modes in sunspots, a few 10 ppm and 10 minutes for the granulation turn around, a few 100 ppm and weeks for the lifetime of plages and faculae, 1000 ppm and 27 days for the rotational signal from spots, to the long-term cycles of 90 yr (Gleissberg cycle), 200 - 300 yr (Wolf, Spörer, Maunder minima), 2,400 yr from 14C tree-ring data, and possibly in excess of 100,000 yr.

The Sun's Influence on Climate

2015 ◽  
Author(s):  
Joanna D. Haigh ◽  
Peter Cargill
Keyword(s):  
Solar Radiation ◽  
Sunspot Cycle ◽  
Climate System ◽  
Upper Atmosphere ◽  
Atmospheric Composition ◽  
The Sun ◽  
Important Relationship ◽  
Earth’S Climate ◽  
And Behavior

The Earth's climate system depends entirely on the Sun for its energy. Solar radiation warms the atmosphere and is fundamental to atmospheric composition, while the distribution of solar heating across the planet produces global wind patterns and contributes to the formation of clouds, storms, and rainfall. This book provides an unparalleled introduction to this vitally important relationship. The book covers the basic properties of the Earth's climate system, the structure and behavior of the Sun, and the absorption of solar radiation in the atmosphere. It explains how solar activity varies and how these variations affect the Earth's environment, from long-term paleoclimate effects to century timescales in the context of human-induced climate change, and from signals of the 11-year sunspot cycle to the impacts of solar emissions on space weather in our planet's upper atmosphere.

Strong Shear and High-Amplitude Activity Cycle in a Metal-Rich Solar Analogue

2017 ◽  
Vol 14 (S339) ◽  
pp. 104-105
Author(s):  
C. Karoff
Keyword(s):  
Differential Rotation ◽  
Activity Cycle ◽  
High Amplitude ◽  
Solar Dynamo ◽  
The Sun ◽  
Magnetic Cycle ◽  
Photometric Variability ◽  
Strong Shear ◽  
Complete Set ◽  
Open Question

AbstractOver an 11-year cycle the Sun changes its brightness by less than 0.1%. However, it is an open question how strong the Sun’s photometric variability was in the distant past. One way to answer that is to study other Sun-like stars and compare their photometric variability with that of the Sun. In a recent paper, we presented ground-based spectroscopic observations of a 7.4-year cycle in the solar analogue HD 173701. Complemented with observations from the Kepler space telescope, those data constitute the most complete set of observations of a stellar cycle ever obtained for any Sun-like star. They reveal that HD 173701 has strong solar-like differential rotation and a magnetic cycle comparable to the cycle generated by the solar dynamo, but with a resulting variability twice the amplitude of that observed in the Sun.

Cyclic Evolution of Sunspots: Gleaning New Results from Old Data

2000 ◽  
Vol 179 ◽  
pp. 163-165
Author(s):  
S. K. Solanki ◽  
M. Fligge ◽  
P. Pulkkinen ◽  
P. Hoyng
Keyword(s):  
Sunspot Number ◽  
Sunspot Cycle ◽  
Preliminary Results ◽  
Butterfly Diagram

AbstractThe records of sunspot number, sunspot areas and sunspot locations gathered over the centuries by various observatories are reanalysed with the aim of finding as yet undiscovered connections between the different parameters of the sunspot cycle and the butterfly diagram. Preliminary results of such interrelationships are presented.

Regression Analysis of Sunspot Numbers for the Solar Cycle 24 in Comparison to Previous Three Cycles

2014 ◽  
Vol 4 (2) ◽  
pp. 477-483
Author(s):  
Debojyoti Halder
Keyword(s):  
Regression Analysis ◽  
Solar Cycle ◽  
Sunspot Number ◽  
The Sun ◽  
Sunspot Numbers ◽  
Solar Cycle 24 ◽  
Current Cycle ◽  
Cycle 24

Sunspots are temporary phenomena on the photosphere of the Sun which appear visibly as dark spots compared to surrounding regions. Sunspot populations usually rise fast but fall more slowly when observed for any particular solar cycle. The sunspot numbers for the current cycle 24 and the previous three cycles have been plotted for duration of first four years for each of them. It appears that the value of peak sunspot number for solar cycle 24 is smaller than the three preceding cycles. When regression analysis is made it exhibits a trend of slow rising phase of the cycle 24 compared to previous three cycles. Our analysis further shows that cycle 24 is approaching to a longer-period but with smaller occurrences of sunspot number.

scholarly journals ESTIMATION OF PERIOD OF LONG-TERM OSCILLATIONS OF FACULAR FORMATIONS ON THE SUN

2019 ◽  
Author(s):  
P.V. Strekalova ◽  
◽  
A.A. Solov’ev ◽  
V.V. Smirnova ◽  
Y.A. Nagovitsyn ◽  
...  
Keyword(s):  
The Sun
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