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1.
Some comments on the problem of solar cycle prediction   总被引：3，自引：0，他引：3  
V. N. Obridko 《Solar physics》1995,156(1):179-190
The paper provides a number of regression equations that can be used to calculate the height of the odd Wolf number cycle. The feasibility of the rule of Gnevyshev-Ohl is analyzed as applied to the geomagneticaa-index. A modified rule of Gnevyshev-Ohl has been formulated to describe the behaviour ofaa-indices. A new method is suggested for early prediction of the next solar cycle. In this method, the angular coefficient (straightline slope) of linear dependence ofaa-indices on the Wolf number at the descending branch of the cycle has been used as a prediction index. It is shown to a high degree of certainty that the new prediction index is related to the height of the forthcoming cycle. While the methods based on the ratio of the even-odd cycles in a pair give very high values of cycle 23 maximum (203.2 ± 10.7), our new index, on the contrary, gives very low values (74.7 ± 6.9). There are some contradictory symptoms indicating that the forthcoming cycle 23 is likely to violate the regularities established for the past 125 years.  相似文献   

2.
Jain  Kiran  Tripathy  S.C.  Bhatnagar  A.  Kumar  Brajesh 《Solar physics》2000,192(1-2):487-494
We have obtained empirical relations between the p-mode frequency shift and the change in solar activity indices. The empirical relations are determined on the basis of frequencies obtained from BBSO and GONG stations during solar cycle 22. These relations are applied to estimate the change in mean frequency for the cycle 21 and 23. A remarkable agreement between the calculated and observed frequency shifts for the ascending phase of cycle 23, indicates that the derived relations are independent of epoch and do not change significantly from cycle to cycle. We propose that these relations could be used to estimate the shift in p-mode frequencies for past, present and future solar activity cycles, if the solar activity index is known. The maximum frequency shift for cycle 23 is estimated to be 265±90 nHz, corresponding to a predicted maximum smoothed sunspot number 118.1±35.  相似文献   

3.
The polar magnetic field near the cycle minimum is known to correlate with the height of the next sunspot maximum. There is reason to believe that the hemispheric coupling can play an important role in forming the next cycle. The meridional component of the large-scale magnetic field can be one of the hemispheric coupling indices. For our analysis we have used the reconstructed data on the large-scale magnetic field over 1915–1986. We show that in several cycles not only the height but also the general course of the cycle can be described in this way about 6 years in advance. This coupling has been confirmed by the currently available data from 1976 to 2016, but the ratio of the meridional field to the total absolute value of the field vector has turned out to be a more promising parameter. In this paper it was calculated at a height of ～70 Mm above the photosphere. The date of the forthcoming minimum is estimated using this parameter to be mid-2018; using the global field as a forecast parameter gives a later date of the minimum, early 2020.  相似文献   

4.
We present a brief review of predictions of solar cycle maximum amplitude with a lead time of 2 years or more. It is pointed out that a precise prediction of the maximum amplitude with such a lead-time is still an open question despite progress made since the 1960s. A method of prediction using statistical characteristics of solar cycles is developed: the solar cycles are divided into two groups, a high rising velocity (HRV) group and a low rising velocity (LRV) group, depending on the rising velocity in the ascending phase for a given duration of the ascending phase. The amplitude of Solar Cycle 24 can be predicted after the start of the cycle using the formula derived in this paper. Now, about 5 years before the start of the cycle, we can make a preliminary prediction of 83.2-119.4 for its maximum amplitude.  相似文献   

5.
The paper focus on the variation character of sunspot number and solar cycles based on the new version sunspot number (SSN) data. According to seven main variables describing solar cycles, including peak value, the length of cycle, the length of ascending phase, the ratio of the ascending time to the descending time, slope, half width, and area under the curve of solar cycle, clustering, principal component and factor analysis, are applied to analyze variation characteristic and patterns of the 24 solar cycles. We cluster these 24 cycles to find groups in these solar cycles, and search for the main factor determining strength, length and occurrence time of the peak, and the furthest cycle from the average. The cycles within a cluster will be similar or related to one another and different from or unrelated to the cycles in other clusters. These results could help us search for similar cycles conveniently, obtain the understanding of the characteristics of solar cycle variation and analysis of sunspot number change and evolution characteristics, and analyze the origin and the variation mechanism of solar cycle.  相似文献   

6.
Sunspot numbers form a comprehensive, long-duration proxy of solar activity and have been used numerous times to empirically investigate the properties of the solar cycle. A number of correlations have been discovered over the 24 cycles for which observational records are available. Here we carry out a sophisticated statistical analysis of the sunspot record that reaffirms these correlations, and sets up an empirical predictive framework for future cycles. An advantage of our approach is that it allows for rigorous assessment of both the statistical significance of various cycle features and the uncertainty associated with predictions. We summarize the data into three sequential relations that estimate the amplitude, duration, and time of rise to maximum for any cycle, given the values from the previous cycle. We find that there is no indication of a persistence in predictive power beyond one cycle, and we conclude that the dynamo does not retain memory beyond one cycle. Based on sunspot records up to October 2011, we obtain, for Cycle 24, an estimated maximum smoothed monthly sunspot number of 97±15, to occur in January??C?February 2014 ± six months.  相似文献   

7.
本文首先分析指出第22太阳周前半周的太阳活动所具有的特点:(1)有最高的起始极小值;(2)上升速度快;(3)升段时间最短;(4)峰期长,可能有双峰;(5)个别时段活动水平极高.然后对第22周后半周的活动情况做了预计:在后半周将可能观测到大约2800个活动区,28000个耀斑,210个X级X射线爆发和大约80次太阳质子事件.最后,应用本文给出的太阳周参量关系式.预报第23周太阳黑子数月均平滑值的峰值为119,位于2001.6年.  相似文献   

8.
Thirteen synoptic maps of expansion rate of the coronal magnetic field (CMF; RBR) calculated by the so-called ‘potential model’ are constructed for 13 Carrington rotations from the maximum phase of solar activity cycle 22 through the maximum phase of cycle 23. Similar 13 synoptic maps of solar wind speed (SWS) estimated by interplanetary scintillation observations are constructed for the same 13 Carrington rotations as the ones for the RBR. The correlation diagrams between the RBR and the SWS are plotted with the data of these 13 synoptic maps. It is found that the correlation is negative and high in this time period. It is further found that the linear correlation is improved if the data are classified into two groups by the magnitude of radial component of photospheric magnetic field, |Bphor|; group 1, 0.0 G ≦ |Brpho| < 17.8 G and group 2, 17.8 G ≦ |Brpho|. There exists a strong negative correlation between the RBR and the SWS for the group 1 in contrast with a weak negative correlation for the group 2. Group 1 has a double peak in the density distribution of data points in the correlation diagram; a sharp peak for high-speed solar wind and a low peak for low-speed solar wind. These two peaks are located just on the axis of maximum variance of data points in the correlation diagram. This result suggests that the solar wind consists of two major components and both the high-speed and the low-speed winds emanating from weak photospheric magnetic regions are accelerated by the same mechanism in the course of solar activity cycle. It is also pointed out that the SWS can be estimated by the RBR of group 1 with an empirical formula obtained in this paper during the entire solar activity cycle.  相似文献   

9.
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   

10.
The correlation between various parameters of solar cycles 1–23 is investigated. The derived regressions are used to make predictions of solar cycles 24 and 25. It is expected that solar cycle 24 will reach its maximum amplitude of 110.2 ± 33.4 in April–June 2012 and the next minimum will occur in December 2018–January 2019. The duration of solar cycle 24 will be about 11.1 years. Solar cycle 25 will reach its maximum amplitude of 112.3 ± 33.4 approximately in April–June 2023.  相似文献   

11.
The differential rotation of the solar corona has been analyzed using as the input data the brightness of the coronal green line Fe xiv 530.3 nm for more than five activity cycles. It is found that the character of rotation of the solar corona changes during the activity cycle. Approximately at the middle of the descending branch the differential rotation is weakly pronounced, while the greatest differential gradient is observed at the ascending branch and, occasionally, at the maximum of the cycle. An explanation of this difference has been suggested. The total rotation rate of the corona can be represented as a superposition of two rotation modes (components) – the fast and slow ones. The synodic period of the fast mode near the equator is about 27 days, increasing slightly with latitude. The synodic period of the slow mode exceeds 30 days. The changing relative fraction of these two modes results in variation of the latitude dependence of the observed rotation rate during the activity cycle. The characteristics of two principal types of differential rotation of the solar corona have been determined. The first type consists of the fast mode alone and is established approximately at the middle of the descending branch of the cycle. The second type is the sum of both modes with the fast mode dominating at low latitudes and the slow mode at high latitudes. The results obtained can be used for in-depth study of interaction of the velocity field and dynamo mechanism in the Sun and stars.  相似文献   

12.
Solar Wind Forecasting with Coronal Holes   总被引：1，自引：0，他引：1  
An empirical model for forecasting solar wind speed related geomagnetic events is presented here. The model is based on the estimated location and size of solar coronal holes. This method differs from models that are based on photospheric magnetograms (e.g., Wang–Sheeley model) to estimate the open field line configuration. Rather than requiring the use of a full magnetic synoptic map, the method presented here can be used to forecast solar wind velocities and magnetic polarity from a single coronal hole image, along with a single magnetic full-disk image. The coronal hole parameters used in this study are estimated with Kitt Peak Vacuum Telescope He I 1083 nm spectrograms and photospheric magnetograms. Solar wind and coronal hole data for the period between May 1992 and September 2003 are investigated. The new model is found to be accurate to within 10% of observed solar wind measurements for its best 1-month period, and it has a linear correlation coefficient of ∼0.38 for the full 11 years studied. Using a single estimated coronal hole map, the model can forecast the Earth directed solar wind velocity up to 8.5 days in advance. In addition, this method can be used with any source of coronal hole area and location data.  相似文献   

13.
The Shape of The Sunspot Cycle: A One-Parameter Fit   总被引：1，自引：0，他引：1  
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14.
On the basis of butterfly diagrams for the period 1874-present (covering late cycle 11 through late cycle 21), features are identified that may be useful for predicting the beginning and the length of a solar cycle, as well as the discernment of turning points in the period-growth dichotomy. For example, the first occurrence of high latitude new cycle spots during the decline of an old cycle usually occurs in the northern hemisphere, regardless of bimodal class, about 1.4 yr before new cycle minimum or about 5.4 yr after old cycle maximum, being true for 7 out of the 10 data-available cycles. Also, the last occurrence of high latitude old cycle spots tends to occur in the southern hemisphere when the old cycle is of long period (4 out of 4 cycles) and to occur in the northern hemisphere when the old cycle is of short period (4 out of 5 cycles). Application of these sorting features to the butterfly diagram for late cycle 21 yields candidate dates for the last occurrence of high latitude old cycle spots which in every case predict that cycle 21 will be a long-period cycle, ending after July 1987. Taking April 1985 to be the first occurrence of high latitude new cycle (cycle 22) spots during the decline of cycle 21 (the old cycle), one deduces that the last occurrence of high latitude old cycle spots was September 1983 (occurring in the southern hemisphere) and predicts that minimum for cycle 22 will be about 1986.7 ± 1.1 yr, or that it should occur before the end of 1987.  相似文献   

15.
Relationships between solar wind speed and expansion rate of the coronal magnetic field have been studied mainly by in-ecliptic observations of artificial satellites and some off-ecliptic data by Ulysses. In this paper, we use the solar wind speed estimated by interplanetary scintillation (IPS) observations in the whole heliosphere. Two synoptic maps of SWS estimated by IPS observations are constructed for two Carrington rotations CR 1830 and 1901; CR 1830 starting on the 11th of June, 1990 is in the maximum phase of solar activity cycle and CR 1901 starting on the 29th of September, 1995 is in the minimum phase. Each of the maps consist of 64800 (360×180) data points. Similar synoptic maps of expansion rate of the coronal magnetic field (RBR) calculated by the so-called potential model are also constructed under a radial field assumption for CR 1830 and CR1901. Highly significant correlation (r=–0.66) is found between the SWS and the RBR during CR1901 in the solar minimum phase; that is, high-speed winds emanate from photospheric areas corresponding to low expansion rate of the coronal magnetic field and low speed winds emanate from photospheric areas of high expansion rate. A similar result is found during CR 1830 in solar maximum phase, though the correlation is relatively low (r=–0.29). The correlation is improved when both the data during CR 1830 and CR 1901 are used together; the correlation coefficient becomes –0.67 in this case. These results suggest that the correlation analysis between the SWS and the RBR can be applied to estimate the solar wind speed from the expansion rate of the coronal magnetic field, though the correlation between them may depend on the solar activity cycle. We need further study of correlation analysis for the entire solar cycle to get an accurate empirical equation for the estimation of solar wind speed. If the solar wind speed is estimated successfully by an empirical equation, it can be used as an initial condition of a solar wind model for space weather forecasts.  相似文献   

16.
T. W. Cole 《Solar physics》1973,30(1):103-110
The techniques of power spectral analysis are used to determine significant periodicities in the annual mean relative sunspot numbers. The main conclusion is that a period of 10.45 yr is very basic and can be associated with an excitation of new solar cycles. When combined with a period of 11.8 yr, associated here with the free-running length of a solar cycle, the mean cycle length of 11.06 yr and a phase variation of 190 yr are explained. Similarly the amplitude variations with periods 88 and 59 yr (previously described as the 80-yr cycle) are due to an amplitude modulation of the solar cycle by a period of 11.9±0.3 yr. The results dispute several associations of planetary position and solar activity.Radiophysics Publication RPP 1647, January, 1973.  相似文献   

17.
Longterm Prediction of Solar Activity Using the Combined Method   总被引：2，自引：0，他引：2  
Hanslmeier  Arnold  Denkmayr  Klaus  Weiss  Peter 《Solar physics》1999,184(1):213-218
The Combined Method is a non-parametric regression technique for long-term prediction of smoothed monthly sunspot numbers. Starting from a solar minimum, a prediction of the succeeding maximum is obtained by using a dynamo-based relation between the geomagnetic aa index and succeeding solar maxima. Then a series of predictions is calculated by computing the weighted average of past cycles of similar level. This technique leads to a good prediction performance, particularly in the ascending phase of the solar cycle where purely statistical methods tend to be inaccurate. For cycle 23 the combined method predicts a maximum of 160 (in terms of smoothed sunspot number) early in the year 2000.  相似文献   

18.
Statistical behavior of sunspot groups on the solar disk   总被引：1，自引：0，他引：1  
K.J. Li  H.F. Liang  H.S. Yun  X.M. Gu 《Solar physics》2002,205(2):361-370
In the present study we have produced a diagram of the latitude distribution of sunspot groups from the year 1874 through 1999 and examined statistical characteristics of the mean latitude of sunspot groups. The reliability of the observed data set prior to solar cycle 19 is found quite low as compared with that of the data set observed after cycle 19. A correlation is found between maximum latitude at which first sunspot groups of a new cycle appear and the maximum solar activity of the cycle. It is inferred that solar magnetic activity during the early part of an extended solar cycle may contain some information about the strength of forthcoming solar cycle. A formula is given to describe latitude change of sunspot groups with time during an extended solar cycle. The latitude-migration velocity is found to be largest at the beginning of solar cycle and decreases with time as the cycle progresses with a mean migration velocity of about 1.61° per year.  相似文献   

19.
During sunspot cycles 20 and 21, the maximum in smoothed 10.7-cm solar radio flux occurred about 1.5 yr after the maximum smoothed sunspot number, whereas during cycles 18 and 19 no lag was observed. Thus, although 10.7-cm radio flux and Zürich suspot number are highly correlated, they are not interchangeable, especially near solar maximum. The 10.7-cm flux more closely follows the number of sunspots visible on the solar disk, while the Zürich sunspot number more closely follows the number of sunspot groups. The number of sunspots in an active region is one measure of the complexity of the magnetic structure of the region, and the coincidence in the maxima of radio flux and number of sunspots apparently reflects higher radio emission from active regions of greater magnetic complexity. The presence of a lag between sunspot-number maximum and radio-flux maximum in some cycles but not in others argues that some aspect of the average magnetic complexity near solar maximum must vary from cycle to cycle. A speculative possibility is that the radio-flux lag discriminates between long-period and short-period cycles, being another indicator that the solar cycle switches between long-period and short-period modes.Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation.  相似文献   

20.
Meyer  F. De 《Solar physics》2003,217(2):349-366
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   

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