共查询到20条相似文献，搜索用时 15 毫秒
1.
The average values of the parameters of the solar wind and the interplanetary magnetic field at the Earth's orbit are calculated by using the results of direct measurements performed in the current and three previous solar cycles. Individual and general features of each cycle are analyzed by the method of superposition of epochs and hysteresis curves. The similarity in trends of solar cycles 23 and 20 at their growth phase is revealed. This gives additional reason to expect that the current solar cycle as a whole will be weaker than the two previous cycles. 相似文献
2.
The shape of the sunspot cycle 总被引：5，自引：0，他引：5
The temporal behavior of a sunspot cycle, as described by the International sunspot numbers, can be represented by a simple
function with four parameters: starting time, amplitude, rise time, and asymmetry. Of these, the parameter that governs the
asymmetry between the rise to maximum and the fall to minimum is found to vary little from cycle to cycle and can be fixed
at a single value for all cycles. A close relationship is found between rise time and amplitude which allows for a representation
of each cycle by a function containing only two parameters: the starting time and the amplitude. These parameters are determined
for the previous 22 sunspot cycles and examined for any predictable behavior. A weak correlation is found between the amplitude
of a cycle and the length of the previous cycle. This allows for an estimate of the amplitude accurate to within about 30%
right at the start of the cycle. As the cycle progresses, the amplitude can be better determined to within 20% at 30 months
and to within 10% at 42 months into the cycle, thereby providing a good prediction both for the timing and size of sunspot
maximum and for the behavior of the remaining 7–12 years of the cycle.
The U.S. Government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged. 相似文献
3.
V. M. Fedorov 《Solar System Research》2012,46(2):170-176
It can be concluded from the calculations performed of interannual variations of the distance between the Sun and the Earth
in the moments of the Earth’s position in the equinoctial and solstitial points that the mean amplitude (approximately the
same for all the equinoctial and solstitial points) is determined to be equal to 5700 km (at the maximum values being approximately
equal to 15000 km). The values of the solar constant have been calculated on the basis of the data of varying distances, and
the values of its interannual variability (for the period from 1900 up to 2050) have determined. Based on the analysis of
the series, new periodic characteristics of a long-term variation of the solar constant, related to the celestial-mechanical
process, namely, to the perturbed orbital motion of the Earth, are obtained. A three-year cycle is distinguished in the interannual
variability of the solar constant, which alternates with a two-year cycle every eight and eleven years. The amplitude of the
interannual variability in the series of equinoctial and solstitial points is on average about 0.1 W/m2 (about 0.008% of the solar constant value). This is comparable to the interannual variability of the solar constant in the
eleven-year cycle of the solar activity. The series obtained can be represented by alternation of eleven-year and eight-year
cycles. The eleven-year cycle is composed of three three-year cycles and one two-year cycle, and the eight-year cycle is composed
of two three-year cycles and one two-year cycle. 相似文献
4.
In this paper, the method of similar cycles is applied to predict the start time of the 24th cycle of solar activity and the sunspot numbers in the later part of the descending phase of cycle 23. According to the characteristic parameters and the morphological characters of the descending phase of cycle 23 and of cycles 9, 10, 11, 15, 17 and 20 (cycles selected as the similar cycles for the descending phase of cycle 23), the start time of cycle 24 is predicted to be in 2007 yr 5 ± 1m, the smoothed monthly mean spot number, 7.1 ± 2.6 and the length of the 23rd cycle, 11.1 yr. These results agree rather well with those stated in Refs.[11] & [12] as well as those of MSFC. Our work shows that the method of similar cycles can well be applied to the long-term prediction of solar activity. 相似文献
5.
The statistics of extreme values is used to investigate the statistical properties of the largest areas of sunspots and photospheric faculae per solar cycle. The largest values of the synodic-solar-rotation mean areas of umbrae, whole spots and faculae, which have been recorded for nine solar cycles, are each shown to comply with the general form of the extreme value probability function. Empirical expressions are derived for the three extreme value populations from which the characteristic statistical parameters, namely the mode, median, mean and standard deviation, can be calculated for each population. These three extreme value populations are also used to find the expected ranges of the extreme areas in a group of solar cycles as a function of the number of cycles in the group. The extreme areas of umbrae and whole spots have a dispersion comparable to that found by Siscoe for the extreme values of sunspot number, whereas the extreme areas of faculae have a smaller dispersion which is comparable to that found by Siscoe for the largest geomagnetic storm per solar cycle. The expected range of the largest sunspot area per solar cycle for a group of one hundred cycles appears to be inconsistent with the existence of the prolonged periods of sunspot minima that have been inferred from the historical information on solar variability. This inconsistency supports the contention that there are temporal changes of solar-cycle statistics during protracted periods of sunspot minima (or maxima). Indeed, without such temporal changes, photospheric faculae should have been continually observable throughout the lifetime of the Sun. 相似文献
6.
It has been found that sunspot cycles 10–21, represented by quarterly mean values of Zürich sunspot number, can be suitably described by the F-distribution density function provided it is modified by introducing five characteristic parameters, in order to achieve an optimal fitting of each cycle. The average cycle calculated from cycles 10–21 has been used as a basis to forecast time and magnitude of the maximum of each cycle, as a function of various numbers of the first quarterly mean values in the beginning N = 8 to 16 quarters. The standard deviations at a 99% significance level calculated from the observed values depend on N, and vary from 1.6 to 1.1 quarters and 65 to 16 units of sunspot number. A rather sufficient forecast is obtained from N = 12 quarters (with inaccuracy of ± 1.5 quarters and ± 24 units); the forecast for cycle 22 yielded, for N = 12, the values t
m
= (15.4 ± 1.5) quarters ( 1990.I) and f(t
m
) = (175 ±24 units). 相似文献
7.
B. P. Tritakis 《Astrophysics and Space Science》1982,82(2):463-471
There are strong indications that successive 11-year cycles they belong to the same 22-year cycle aren't independent. However, indications for interaction between successive 11-year cycles they don't belong to the same 22-year cycle are weak but not negligible.The evolution of a certain 11-year cycle seems to depend on some basic parameters they characterize the configuration of the previous cycle. This dependency can provide us a simple way of estimating solar activity elements one 11-year cycle in advance. 相似文献
8.
V. K. Mishra Meera Gupta B. N. Mishra S. K. Nigam A. P. Mishra 《Journal of Astrophysics and Astronomy》2008,29(1-2):257-262
The long-term modulation of cosmic ray intensity (CRI) by different solar activity (SA) parameters and an inverse correlation between individual SA parameter and CRI is well known. Earlier, it has been suggested that the concept of multi-parametric modulation of CRI may play an important role in the study of long-term modulation of CRI. In the present study, we have tried to investigate the combined effect of a set of two SA parameters in the long-term modulation of CRI. For this purpose, we have used a new statistical technique called “Running multiple correlation method”, based on the “Running cross correlation method”. The running multiple correlation functions among different sets of two SA parameters (e.g., sunspot numbers and solar flux, sunspot numbers and coronal index, sunspot numbers and grouped solar flares, etc.) and CRI have been correlated separately. It is found that the strength of multiple correlation (among two SA parameters and CRI) and cross correlation (between individual SA parameter and CRI) is almost similar throughout the period of investigation (1955–2005). It is also found that the multiple correlations among various SA parameters and CRI is stronger during ascending and descending phases of the solar cycles and it becomes weaker during maxima and minima of the solar cycles, which is in accordance with the linear relationship between SA parameters and CRI. The values of multiple correlation functions among different sets of SA parameters and CRI fall well within the 95% confidence interval. In the view of odd-even hypothesis of solar cycles, the strange behaviour of present cycle 23 (odd cycle), as this is characterized by many peculiarities with double peaks and many quiet periods (Gnevyshev gaps) interrupted the solar activity (for example April 2001, October–November 2003 and January 2005), leads us to speculate that the solar cycle 24 (even cycle) might be of exceptional nature. 相似文献
9.
To predict the key parameters of the solar cycle,a new method is proposed based on the empirical law describing the correlation between the maximum height of the preceding solar cycle and the entropy of the forthcoming one.The entropy of the forthcoming cycle may be estimated using this empirical law,if the maximum height of the current cycle is known.The cycle entropy is shown to correlate well with the cycle's maximum height and,as a consequence,the height of the forthcoming maximum can be estimated.In turn,the correlation found between the height of the maximum and the duration of the ascending branch(the Waldmeier rule)allows the epoch of the maximum,Tmax,to be estimated,if the date of the minimum is known.Moreover,using the law discovered,one can find out the analogous cycles which are similar to the cycle being forecasted,and hence,obtain the synoptic forecast of all main features of the forthcoming cycle.The estimates have shown the accuracy level of this technique to be 86%.The new regularities discovered are also interesting because they are fundamental in the theory of solar cycles and may provide new empirical data.The main parameters of the future solar cycle 24 are as follows: the height of the maximum is Wmax = 95±20,the duration of the ascending branch is Ta = 4.5±0.5 yr,the total cycle duration according to the synoptic forecast is 11.3 yr. 相似文献
10.
The Waldmeier effect is considered for empirical parameters of the functions that approximate solar activity cycles nos. 8–23 according to the Zurich numbering system. The cycle amplitude is found to linearly depend on the mean rate of rise in solar activity during its rising phase. This relationship seems to be a fundamental property of 11-year cycles and may be a reason for differences in solar cycles. 相似文献
11.
Solar activity cycles,north/south asymmetries,and differential rotation associated with solar spin-orbit variations 总被引：1，自引：0，他引：1
The possible role of the Sun's planetary-induced spin-orbit dynamics in the generation of various solar oscillations is examined using simple approaches and heuristic models. Theoretically, the 22.5-yr dipole inversion magnetic cycle and the recently described 17-yr neutral line topology cycle can be derived from the non-linear mixing of two oscillations with periods of approximately 20 and 165 years. Oscillations with such periods are observed in two aspects of the Sun's spin-orbit dynamics. The 20-yr oscillation is the fundamental variation in the angular momentum of the solar body with respect to the solar system center-of-mass, while the 165-yr oscillation is the lowest-frequency component of the spin projection variations. It is shown that these two oscillations when mixed non-linearly yield, to a 1st-order approximation, the correct phase and frequency of the observed 17.5- and 22.5-yr magnetic cycles. By allowing an asymmetric shape to the 165-yr oscillation, the frequency modulation inherent in the Hale cycle (and sunspot cycle) is reproduced, yielding a more accurate estimate of solar activity. The asymmetric 165-yr oscillation matches the combination of the two lowest frequency components (165- and 84-yr periods) of the spin projection variations. Hemispheric sunspot asymmetry cycles, north/south differences in convective zone rotational velocities, and meridional flows are also shown to be expected byproducts of classical spin-orbit effects. Finally, the problem of low activity epochs (e.g., Maunder minimum) can be seen as a natural outcome of the interactions among the driving and driven oscillations involved in the conservation of solar system angular momentum. 相似文献
12.
We used two methods to investigate the periodic behavior of sunspot counts in four categories for the time period January 1986?–?October 2013. These categories include the counts from simple (A and B), medium (C), large (D, E, and F), and final (final-stage; H) sunspot groups. We used i) the multitaper method with red noise approximation, and ii) the Morlet wavelet transform for periodicity analysis. Our main findings are that 1) the solar rotation periodicity of about 25 to 37 days, which is of obvious significance, is found in all groups with at least a 95 % significance level; 2) the periodic behavior of a cycle is strongly related to its amplitude and group distribution during the cycle; 3) the appearance of periods follows the amplitude of the investigated solar cycles; and that 4) meaningful periods do not appear during the minimum phases of the investigated cycles. We would like to underline that the cyclic behavior of all categories is not exactly the same; there are some differences between these groups. This result can provide a clue for the better understanding of solar cycles. 相似文献
13.
L. A. Plyusnina 《Solar physics》2010,261(2):223-232
There are two types of active longitudes (ALs) in terms of the distribution of sunspot areas: long-lived and intra-cyclic
ALs. The rotation period of the long-lived ALs has been determined by a new method in this paper. The method is based on the
property of ALs to be maintained over several cycles of solar activity. The daily values of sunspot areas for 1878 – 2005
are analyzed. It is shown that the AL positions remain almost constant over a period of about ten cycles, from cycle 13 to
cycle 22. The rotation period was found to be 27.965 days during this period. The dispersion in AL positions is about 26°
from cycle to cycle, which is half of the dispersion observed in the Carrington system. The ALs in the growth phase of the
activity cycle are more stable and pronounced. The excess in solar activity in the ALs over adjacent longitudinal intervals
is about 12 – 14%. It is shown that only one long-lived AL can be observed at one time on the Sun, as a rule. 相似文献
14.
通过对１２－２２周（（１８７８－１９９５年）太阳大黑子群分布南北半球不对称的整体特征的研究,探讨了太阳活动周的长期演化趋势．约定Ｎ与Ｓ分别表示北南半球大黑子群数之和,ＢＮ与ＢＳ为北南半球大黑子群的纬度和．由这４个物理量定义了太阳活动周的３个参量：（１）太阳活动不对称指数ＡＳ＝（Ｎ－Ｓ）／（Ｎ＋Ｓ）;（２）平均纬度ＢＴ＝（ＢＮ＋ＢＳ）／（Ｎ＋Ｓ）,ＢＳ取负值;（３）太阳活动带的宽度ＢＷ＝ＢＮ／Ｎ－ＢＳ／Ｓ．对上述１１个活动周,得到了有关８０年周期的性质及奇偶数周大黑子群数变化的有意义的统计结果． 相似文献
15.
A new method for estimating the 11-year solar cycle periodicity was developed. The method is based on the approximation of
cyclic changes of the mean latitude of sunspot groups. In general, the intervals of cycle repetitions estimated here do not
contradict analogous data obtained earlier by the traditional method. It is confirmed also that the frequency at which 22-year
cycles follow each other depends on the phase of secular changes in solar activity. 相似文献
16.
The mean annual sunspot record for the time interval 1700–2002 can be considered as a sequence of independent, partly overlapping events, triggered quasi-periodically at intervals of the order of 11 years. The individual cycles are approximated by the step response of a band-pass dynamical system and the resulting model consists of the superposition of the response to the independent pulses. The simulated sunspot data explain 98.4% of the cycle peak height variance and the residual standard deviation is 8.2 mean annual sunspots. An empirical linear relationship is found between the amplitude of the transfer function model for each cycle and the pulse interval of the preceding cycle that can be used as a tool of short-term forecasting of solar activity. A peak height of 112 for the solar cycle 23 occurring in 2000 is predicted, whereas the next cycle would start at about 2007 and will have a maximum around 110 in 2011. Cycle 24 is expected to have an annual mean peak value in the range 95 to 125. The model reproduces the high level of amplitude modulation in the interval 1950–2000 with a decrease afterwards, but the peak values for the cycles 18, 19, 21, and 22 are fairly underestimated. The semi-empirical model also recreates recurring sunspot minima and is linked to the phenomenon of the reversal of the solar magnetic field. 相似文献
17.
The time series of the relative sunspot number is interpreted as a sequence of physical cycles of sunspot activity overlapping
in the minimum. The cycle periodicity, i.e., the time interval between neighboring cycles, can be considered as a quantitative
characteristic of the sequence. Estimates of this interval have been obtained for 11 and 22-year cycles. In the growth phase
and in the century cycle maximum, the 22-year cycles follow one another with an interval of 21 ± 0.4 years, and in the decline
phase, 23 ± 0.3 years. This division of intervals into two groups depending on the century cycle phase should be taken into
consideration when developing a theory of solar activity cycles. 相似文献
18.
A stochastic prediction model for the sunspot cycle is proposed. The prediction model is based on a modified binary mixture
of Laplace distribution functions and a moving-average model over the estimated model parameters. A six-parameter modified
binary mixture of Laplace distribution functions is used for the modeling of the shape of a generic sunspot cycle. The model
parameters are estimated for 23 sunspot cycles independently, and the primary prediction-model parameters are derived from
these estimated model parameters using a moving-average stochastic model. A correction factor (hump factor) is introduced
to make an initial prediction. The hump factor is computed for a given sunspot cycle as the ratio of the model estimated after
the completion of a sunspot cycle (post-facto model) and the prediction of the moving-average model. The hump factors can be applied one at a time over the moving-average
prediction model to get a final prediction of a sunspot cycle. The present model is used to predict the characteristics of
Sunspot Cycle 24. The methodology is validated using the previous Sunspot Cycles 21, 22, and 23, which shows the adequacy
and the applicability of the prediction model. The statistics of the variations of sunspot numbers at high solar activity
are used to provide the lower and upper bound for the predictions using the present model. 相似文献
19.
To investigate the long-term modulation of galactic cosmic rays at the ground-based detector energies, the monthly values of the neutron monitor (Climax, Mt. Washington, Deep River, and Huancayo) and ionization chamber (Cheltenham/Fredericksburg, Huancayo, and Yakutsk) intensities have been correlated with the sunspot numbers (used as a proxy index for transient solar activity) for each phase of sunspot cycles 18 to 22. Systematic differences are found for results concerning odd and even sunspot cycles. During odd cycles (19 and 21) the onset time of cosmic-ray modulation is delayed when compared with the onset time of the sunspot cycle, while they are more similar during even (18, 20, and 22) cycles. Checking the green corona data, on a half-year basis, we found typical heliolatitudinal differences during ascending phases of consecutive sunspot cycles. This finding suggests a significant role of the latitudinal coronal behaviour in the heliospherical dynamics during a Hale cycle. Such effectiveness concerns not only the transient interplanetary perturbations but also the recurrent ones. In fact, when lag between cosmic-ray data and sunspot numbers is considered, the anticorrelation between both parameters is very high (correlation coefficient |r| > 0.9) for all the phases considered, except for the declining ones of cycles 20 and 21, when high-speed solar wind streams coming from coronal holes affect the cosmic-ray propagation, and theRz parameter is no longer the right proxy index for solar-induced effects in the interplanetary medium. 相似文献
20.
In this paper, we used the same four-parameter function as Hathaway, Wilson, and Reichmann (1994) proposed and studied the
temporal behavior of sunspot cycles 12–22. We used the monthly averages of sunspot areas and their 13-point smoothed data.
Our results show the following. (1) The four-parameter function may reduce to a function of only two parameters. (2) As a
cycle progresses, the two-parameter function can be accurately determined after 4–4.5 years from the start of the cycle. A
good prediction can be made for the timing and size of the sunspot maximum and for the behavior of the remaining 5–10 years
of the cycle. (3) The solar activity in the remaining and forthcoming years of cycle 23 is predicted. (4) The smoothed monthly
sunspot areas are more suitable to be employed for prediction at the maximum and the descending period of a cycle, whereas
at the early period of a cycle the (un-smoothed) monthly data are more suitable. 相似文献