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1.
The amplitude of the 11-year cycle measured in the cosmogenic isotope 10Be during the Maunder Minimum is comparable to that during the recent epoch of high solar activity. Because of the virtual absence of the cyclic variability of sunspot activity during the Maunder Minimum this seemingly contradicts an intuitive expectation that lower activity would result in smaller solar-cycle variations in cosmogenic radio-isotope data, or in none, leading to confusing and misleading conclusions. It is shown here that large 11-year solar cycles in cosmogenic data observed during periods of suppressed sunspot activity do not necessarily imply strong heliospheric fields. Normal-amplitude cycles in the cosmogenic radio-isotopes observed during the Maunder Minimum are consistent with theoretical expectations because of the nonlinear relation between solar activity and isotope production. Thus, cosmogenic-isotope data provide a good tool to study solar-cycle variability even during grand minima of solar activity. 相似文献
2.
Solar activity alternates between active and quiet phases with an average period of 11?years, and this is known as the Schwabe cycle. Additionally, solar activity occasionally falls into a prolonged quiet phase (grand solar minimum), as represented by the Maunder Minimum in the 17th century, when sunspots were almost absent for 70?years and the length of the Schwabe cycle increased to 14?years. To examine the consistency of the cycle length characteristics during the grand solar minima, the carbon-14 contents in single-year tree rings were measured using an accelerator mass spectrometer as an index of the solar variability during the grand solar minimum of the 4th century BC. The signal of the Schwabe cycle was detected with a statistical confidence level of higher than 95?% by wavelet analysis. This is the oldest evidence for the Schwabe cycle at the present time, and the cycle length is considered to have increased to approximately 16?years during the grand solar minimum of the 4th century BC. This result confirms the association between the increase of the Schwabe cycle length and the weakening of solar activity, and indicates the possible prolonged absence of sunspots in the 4th century BC as during the Maunder Minimum. Theoretical implications from solar dynamo theory are discussed in order to identify the trigger of prolonged sunspot absence. A possible association between the long-term solar variation around the 4th century BC and terrestrial cooling in this period is also discussed. 相似文献
3.
Long-term changes in the magnetic activity of the Sun were studied in terms of the empirical mode decomposition that revealed
their essential modes. The occurrence of grand minima was also studied in their relation to long-term changes in sunspot activity
throughout the past 11 000 yr. Characteristic timescales of long-term changes in solar activity manifest themselves in the
occurrence of grand minima. A quantitative criterion has been defined to identify epochs of grand minima. This criterion reveals
the important role of secular and bicentennial activity variations in the occurrence of grand minima and relates their amplitudes
with the current activity level, which is variable on a millennial timescale. We have revealed specific patterns in the magnetic
activity between successive grand minima which tend to recur approximately every 2300 yr but occasionally alternate with irregular
changes. Such intermittent activity behavior indicates low dimensional chaos in the solar dynamo due to the interplay of its
dominant modes. The analysis showed that in order to forecast activity level in forthcoming cycles, one should take into account
long-term changes in sunspot activity on a ≈2300-yr timescale. The regularities revealed suggest solar activity to decrease
in the foreseeable future. 相似文献
4.
What the Sunspot Record Tells Us About Space Climate 总被引：1，自引：0，他引：1
The records concerning the number, sizes, and positions of sunspots provide a direct means of characterizing solar activity
over nearly 400 years. Sunspot numbers are strongly correlated with modern measures of solar activity including: 10.7-cm radio
flux, total irradiance, X-ray flares, sunspot area, the baseline level of geomagnetic activity, and the flux of galactic cosmic
rays. The Group Sunspot Number provides information on 27 sunspot cycles, far more than any of the modern measures of solar
activity, and enough to provide important details about long-term variations in solar activity or “Space Climate.” The sunspot
record shows: 1) sunspot cycles have periods of 131± 14 months with a normal distribution; 2) sunspot cycles are asymmetric
with a fast rise and slow decline; 3) the rise time from minimum to maximum decreases with cycle amplitude; 4) large amplitude
cycles are preceded by short period cycles; 5) large amplitude cycles are preceded by high minima; 6) although the two hemispheres
remain linked in phase, there are significant asymmetries in the activity in each hemisphere; 7) the rate at which the active
latitudes drift toward the equator is anti-correlated with the cycle period; 8) the rate at which the active latitudes drift
toward the equator is positively correlated with the amplitude of the cycle after the next; 9) there has been a significant
secular increase in the amplitudes of the sunspot cycles since the end of the Maunder Minimum (1715); and 10) there is weak
evidence for a quasi-periodic variation in the sunspot cycle amplitudes with a period of about 90 years. These characteristics
indicate that the next solar cycle should have a maximum smoothed sunspot number of about 145 ± 30 in 2010 while the following
cycle should have a maximum of about 70 ± 30 in 2023. 相似文献
5.
Measurements of 10Be concentration in the Dye 3 ice core show that magnetic cycles persisted throughout the Maunder Minimum, although the Sun's overall activity was drastically reduced and sunspots virtually disappeared. Thus the dates of maxima and minima can now be reliably estimated. Similar behaviour is shown by a nonlinear dynamo model, which predicts that, after a grand minimum, the Sun's toroidal field may switch from being antisymmetric to being symmetric about the equator. The presence of cyclic activity during the Maunder Minimum limits estimates of the solar contribution to climatic change. 相似文献
6.
A nonlinear dynamo model that allows for the dependence of the turbulent diffusivity on the magnetic field shows the phenomenon
of a hysteresis. In a certain range of dynamo numbers, two types of solutions are possible: decaying oscillations of weak
fields and magnetic cycles with a constant and large amplitude, which are settled depending on the initial conditions. Fluctuations
in α-parameter cause transitions between these two regimes and calculations show the intermittency of magnetic cycles with a relatively
large amplitude and epochs of weak magnetic fields. This behavior can serve as a model of grand minima of solar activity like
the well-known Maunder minimum. 相似文献
7.
Developing the idea of Ruzmaikin (1997, 1998), we have constructed a model of sunspot production using three components of solar magnetic field: the 22-year dynamo field, a weak constant relic field, and a random field. This model can reproduce the main features of sunspot activity throughout the 400-year period of direct solar observations, including two different sunspot activity modes, the present, normal sunspot activity and the Maunder minimum. The two sunspot activity modes could be modeled by only changing the level of the dynamo field while keeping the other two components constant. We discuss the role of the three components and how their relative importance changes between normal activity and great minimum times. We found that the relic field must be about 3–10% of the dynamo field in normal activity times. Also, we find that the dynamo field during the Maunder minimum was small but non-zero, being suppressed typically by an order of magnitude with respect to its value during normal activity times. 相似文献
8.
The sunspot number series forms the longest directly observed index of solar activity and allows one to trace its variations on the time scale of about 400 years since 1610. This time interval covers a wide range from seemingly vanishing sunspots during the Maunder minimum in 1645–1700 to the very high activity during the last 50 years. Although the sunspot number series has been studied for more than a century, new interesting features have been found even recently. This paper gives a review of the recent achievements and findings in long-term evolution of solar activity cycles such as determinism and chaos in sunspot cyclicity, cycles during the Maunder minimum, a general behaviour of sunspot activity during a great minimum, the phase catastrophe and the lost cycle in the beginning of the Dalton minimum in 1790s and persistent 22-year cyclicity in sunspot activity. These findings shed new light on the underlying physical processes responsible for sunspot activity and allow a better understanding of such empirical rules as the Gnevyshev–Ohl rule and the Waldmeier relations. 相似文献
9.
Guido Travaglini 《Solar physics》2017,292(1):23
The Maunder Minimum (MM) was an extended period of reduced solar activity in terms of yearly sunspot numbers (SSN) during 1610?–?1715. The reality of this “grand minimum” is generally accepted in the scientific community, but the statistics of the SSN record suggest a need for data reconstruction. The MM data show a nonstandard distribution compared with the entire SSN signal (1610?–?2014). The pattern does not satisfy the weakly stationary solar dynamo approximation, which characterizes many natural events spanning centuries or even millennia, including the Sun and the stars. Over the entire observation period (1610?–?2014), the reported SSN exhibits statistically significant regime switches, departures from autoregressive stationarity, and growing trends. Reconstruction of the SSN during the pre-MM and MM periods is performed using five novel statistical procedures in support of signal analysis. A Bayesian–Monte Carlo backcast technique is found to be most reliable and produces an SSN signal that meets the weak-stationarity requirement. The computed MM signal for this reconstruction does not show a “grand” minimum or even a “semi-grand” minimum. 相似文献
10.
The problem of whether the solar dynamo is quasi-periodic or chaotic is addressed by examining 1500 years of sunspot, geomagnetic and auroral activity cycles. We find sub-harmonics of the fundamental solar cycle period during the years preceding the Maunder minimum and loss of phase of the subharmonic on emergence from it. These phenomena are indicative of chaos. They indicate that the solar dynamo is chaotic and is operating in a region close to the transition between period doubling and chaos. Since Maunder type minima reoccur irregularly for millennia, it appears that the Sun remains close to this transition to and from chaos. We postulate this as a universal characteristic of solar type stars caused by feedback in the dynamo number. 相似文献
11.
The Maunder Minimum is the period between 1645 and 1715. Its main characteristic is abnormally low and prolonged solar activity. However, some authors have doubted the low level of solar activity during that period by questioning the accuracy and objectivity of the observers. This work presents a particular case of a sunspot observed during the Maunder Minimum with an unusual shape of its umbra and penumbra: a hexagon. This sunspot was observed by Cassini in November 1676, just at the core of the Maunder Minimum. This historical observation is compared with a twin case that occurred recently in May 2016. The conclusion reached is that Cassini’s record is another example of the good quality of the observations that were made during the Maunder Minimum, showing the meticulousness of the astronomers of that epoch. This sunspot observation made by Cassini does not support the conclusions of Zolotova and Ponyavin (Astrophys. J. 800, 42, 2015) that professional astronomers in the seventeenth century only registered round sunspots. Finally, a discussion is given of the importance of this kind of unusual sunspot record for a better assessment of the true level of solar activity in the Maunder Minimum. 相似文献
12.
《Chinese Astronomy and Astrophysics》1982,6(1):84-90
21 naked-eye sunspot records in the 17th century, hitherto unknown, have been gleaned from a large collection of local gazettes of China. Based on these data, together with the telescopic records of contemporary Europe, we discuss in detail the solar activity during the 17th century. We have re-examined Wolf's years of maxima and minima and given improved values. We re-evaluate the question of the “Maunder Minimum” and conclude that it is an incorrect inference due to insufficient data. 相似文献
13.
Solar rotation during the Maunder Minimum 总被引：2，自引：0，他引：2
We have measured solar surface rotation from sunspot drawings made in a.d. 1642–1644 and find probable differences from present-day rates. The 17th century sunspots rotated faster near the equator by 3 or 4%, and the differential rotation between 0 and ±20° latitude was enhanced by about a factor 3. These differences are consistent features in both spots and groups of spots and in both northern and southern hemispheres. We presume that this apparent change in surface rotation was related to the ensuing dearth of solar activity (the Maunder Minimum) which persisted until about 1715.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
14.
R. Brajša H. Wöhl D. Ruždjak B. Vršnak G. Verbanac L. Svalgaard J.-F. Hochedez 《Astronomische Nachrichten》2007,328(10):1013-1015
The interaction between differential rotation and magnetic fields in the solar convection zone was recently modelled by Brun (2004). One consequence of that model is that the Maxwell stresses can oppose the Reynolds stresses, and thus contribute to the transport of the angular momentum towards the solar poles, leading to a reduced differential rotation. So, when magnetic fields are weaker, a more pronounced differential rotation can be expected, yielding a higher rotation velocity at low latitudes taken on the average. This hypothesis is consistent with the behaviour of the solar rotation during the Maunder minimum. In this work we search for similar signatures of the relationship between the solar activity and rotation determined tracing sunspot groups and coronal bright points. We use the extended Greenwich data set (1878–1981) and a series of full-disc solar images taken at 28.4 nm with the EIT instrument on the SOHO spacecraft (1998–2000). We investigate the dependence of the solar rotation on the solar activity (described by the relative sunspot number) and the interplanetary magnetic field (calculated from the interdiurnal variability index). Possible rotational signatures of two weak solar activity cycles at the beginning of the 20th century (Gleissberg minimum) are discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
Radosław Rek 《Solar physics》2010,261(2):337-351
The Maunder Minimum was the time during the second part of the 17th century, nominally from 1645 to 1717 AD, when unusually
low numbers of sunspots were observed. On the basis of numerous recorded observations of auroras in the early 18th century,
the end of the Minimum could be regarded as around 1700, but details of sunspot observations by Jan Heweliusz (Heweliusz,
Machina Coelestis, 1679), John Flamsteed and Philippe de La Hire in 1684 allow us to interpret the Maunder Minimum as the period without a significant
cessation of activity. This Minimum was also recognized in 14C data from trees which grew during the second part of 17th century.
The variation in the production rate of radioactive carbon isotope 14C is due to modulation of the cosmic ray flux producing it by the changing level of solar activity and solar magnetic flux.
Stronger magnetic fields in the solar wind make it more difficult for cosmic rays to reach the Earth, causing a drop in the
production rate of 14C. However, more detailed analyses of 14C data indicate that the highest isotope abundances do not occur at the time of sunspot minima, as would be expected on the
basis of modulation of the cosmic ray flux by the solar magnetic field, but two years after the sunspot number maximum. This
time difference (or phase delay) can be accounted for if in fact there are both solar and non-solar cosmic ray contributions.
Solar flares could also contribute high-energy particles and produce 14C and are generally not most frequent at the time of the highest sunspot numbers in the cycle. 相似文献
16.
Zadig Mouradian 《Solar physics》2013,282(2):553-564
This article proposes a unified observational model of solar activity based on sunspot number and the solar global activity in the rotation of the structures, both per 11-year cycle. The rotation rates show a variation of a half-century period and the same period is also associated to the sunspot amplitude variation. The global solar rotation interweaves with the observed global organisation of solar activity. An important role for this assembly is played by the Grand Cycle formed by the merging of five sunspot cycles: a forgotten discovery by R. Wolf. On the basis of these elements, the nature of the Dalton Minimum, the Maunder Minimum, the Gleissberg Cycle, and the Grand Minima are presented. 相似文献
17.
L. H. Deng J. Y. Song Y. Y. Xiang Y. K. Tang 《Journal of Astrophysics and Astronomy》2011,32(3):401-409
The monthly sunspot numbers compiled by Temmer et al. and the monthly polar faculae from observations of the National Astronomical Observatory of Japan, for the interval of March
1954 to March 1996, are used to investigate the phase relationship between polar faculae and sunspot activity for total solar
disk and for both hemispheres in solar cycles 19, 20, 21 and 22. We found that (1) the polar faculae begin earlier than sunspot
activity, and the phase difference exhibits a consistent behaviour for different hemispheres in each of the solar cycles,
implying that this phenomenon should not be regarded as a stochastic fluctuation; (2) the inverse correlation between polar
faculae and sunspot numbers is not only a long-term behaviour, but also exists in short time range; (3) the polar faculae
show leads of about 50–71 months relative to sunspot numbers, and the phase difference between them varies with solar cycle;
(4) the phase difference value in the northern hemisphere differs from that in the southern hemisphere in a solar cycle, which
means that phase difference also existed between the two hemispheres. Moreover, the phase difference between the two hemispheres
exhibits a periodical behaviour. Our results seem to support the finding of Hiremath (2010). 相似文献
18.
Using the sunspot numbers reported during the Maunder minimum and the empirical relations between the mode frequencies and
solar activity indices, the variations in the total solar irradiance and 10.7 cm radio flux for the period 1645 to 1715 is
estimated. We find that the total solar irradiance and radio flux during the Maunder minimum decreased by 0.19% and 52% respectively,
as compared to the values for solar cycle 22.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
According to research results from solar-dynamo models, the northern and southern hemispheres may evolve separately throughout
the solar cycle. The observed phase lag between the northern and southern hemispheres provides information regarding how strongly
the hemispheres are coupled. Using hemispheric sunspot-area and sunspot-number data from Cycles 12 – 23, we determine how
out of phase the separate hemispheres are during the rising, maximum, and declining period of each solar cycle. Hemispheric
phase differences range from 0 – 11, 0 – 14, and 2 – 19 months for the rising, maximum, and declining periods, respectively.
The phases appear randomly distributed between zero months (in phase) and half of the rise (or decline) time of the solar
cycle. An analysis of the sunspot cycle double peak, or Gnevyshev gap, is conducted to determine if the double-peak is caused
by the averaging of two hemispheres that are out of phase. We confirm previous findings that the Gnevyshev gap is a phenomenon
that occurs in the separate hemispheres and is not due to a superposition of sunspot indices from hemispheres slightly out
of phase. Cross hemispheric coupling could be strongest at solar minimum, when there are large quantities of magnetic flux
at the Equator. We search for a correlation between the hemispheric phase difference near the end of the solar cycle and the
length of solar-cycle minimum, but found none. Because magnetic flux diffusion across the Equator is a mechanism by which
the hemispheres couple, we measured the magnetic flux crossing the Equator by examining Kitt Peak Vacuum Telescope and SOLIS
magnetograms for Solar Cycles 21 – 23. We find, on average, a surplus of northern hemisphere magnetic flux crossing during
the mid-declining phase of each solar cycle. However, we find no correlation between magnitude of magnetic flux crossing the
Equator, length of solar minima, and phase lag between the hemispheres. 相似文献
20.
Large-scale distribution of the sunspot activity of the Sun has been analyzed by using a technique worked out previously (Erofeev, 1997) to study long-lived, non-axisymmetric magnetic structures with different periods of rotation. Results of the analysis have been compared with those obtained by analyzing both the solar large-scale magnetic field and large-scale magnetic field simulated by means of the well-known flux transport equation using the sunspot groups as a sole source of new magnetic flux in the photosphere. A 21-year period (1964–1985) has been examined.The rotation spectra calculated for the total time interval of two 11-year cycles indicate that sunspot activity consists of a series of discrete components (modes) with different periods of rotation. The largest-scale component of the sunspot activity reveals modes with 27-day and 28-day periods of rotation situated, correspondingly, in the northern and southern hemispheres of the Sun, and two modes with rotation periods of about 29.7 days situated in both hemispheres. Such a modal structure of the sunspot activity agrees well with that of the large-scale solar magnetic field. Moreover, the magnetic field distribution simulated with the flux transport equation also reveals the same modal structure. However, such an agreement between the large-scale solar magnetic field and both the sunspot activity and simulated magnetic field is unstable in time; so, it is absent in the northern hemisphere of the Sun during solar cycle No. 20. Thus the sources of magnetic flux responsible for formation of the large-scale, rigidly rotating magnetic patterns appear to be closely connected, but are not identical with the discrete modes of the sunspot activity. 相似文献