Long-term variations of solar magnetic fields derived from geomagnetic data

There are limited homogeneous instrumental observations of the sunspot magnetic fields, but the Earth is a sort of a probe reacting to interplanetary disturbances which are manifestation of the solar magnetic fields. We find correlations between some parameters of geomagnetic activity (the geomagnetic activity “floor”—the minimum value under which the geomagnetic activity cannot fall in a sunspot cycle, and the rate of increase of the geomagnetic activity with increasing sunspot number), and sunspot magnetic fields (the sunspot magnetic field in the cycle minimum, and the rate of increase of the sunspot magnetic field from cycle minimum to cycle maximum). Based on these correlations we are able to reconstruct the sunspot magnetic fields in sunspot minima and maxima since sunspot cycle 9 (mid 19th century).     

On the modeling of visible sunspot layers

One option for a stationary model of the asymmetric sunspot previously presented by the authors is considered. It is shown that the presence of sub-Alfvénic Evershed flows in the sunspot penumbra has almost no effect on the temperature distribution in the dense photospheric layers of the sunspot but significantly lowers the temperature of the chromosphere and the lower corona above the sunspot penumbra up to heights of 5–6 Mm.     

Spatial pattern of photospheric granules in a sunspot neighborhood

Based on high-resolution (0.3 arcsec) observations, we studied the behavior of solar granulation in the neighborhood of a sunspot. The bright granules’ spatial distribution and the granules’ surface density as a function of distance from the center of the sunspot umbra were determined.Bright granules distribute delimiting cells of dimensions in the mesogranular scale. The mean diameter of these cells does not show significant variation with the variation of the magnetic field of the sunspot. The granules’ surface density does not show significant variation with distance to the sunspot umbra. Both results point to a very weak, if any, influence of the sunspot magnetic field at distances greater than 20 arcsec.     

第二十二太阳黑子周特征值预报

太阳活动对地球的影响是人们关心的重要研究课题。太阳黑子相对数作为描述太阳活动的一个参量,虽然不如射电流量密度等参量具有明确的物理意义,但是由于它有较长的观测历史以及在统计上可较好地反映太阳活动的变化,因此在较长期的太阳活动预报等工作中仍是个常用的参量,为有关部门所使用。 将上一个太阳周即第21周的种种预报极值与实际极值165.3比较,可知:一般说     

The Ratio Between the Number of Sunspot and the Number of Sunspot Groups

Data from three solar observatories (Learmonth, Holloman, and San Vito) are used to study the variations in the average number of sunspots per sunspot group. It is found that the different types of sunspot groups and the number of sunspots in these groups have different solar cycle and cycle to cycle variations. The varying ratio between the average number of sunspots and the number of sunspot groups is shown to be a real feature and not a result of changing observational instruments, observers’ experience, calculation schemes, etc., and is a result of variations in the solar magnetic fields. Therefore, the attempts to minimize the discrepancies between the sunspot number and sunspot group series are not justified, and lead to the loss of important information about the variability of the solar dynamo.     

太阳黑子磁场极性指数时间序列

本文根据苏黎世天文台太阳黑子11年周期资料和太阳黑子磁场磁性变化周期特征,构建了太阳黑子磁场磁性指数IM(Magnetic Index)时间序列,用IM(i)表示.为了便于采用数学方法研究太阳黑子磁场磁性指数变化与诸多地球物理现象之间的联系,本文给出了1749～2007年月平均太阳黑子磁场磁性指数时间序列数据.     

太阳黑子活动,磁暴与地震的关系

研究结果表明,全球浅源地震(M_s≥7.8)有3个高发时段:太阳黑子活动的高值年、低值年附近及太阳黑子活动高值年后的第3年。但各太阳周及不同的地震区划单元又有其不同的表现特征。     

Magnetic field variations and spatial configurations of long-period sunspot oscillations according to the SOHO data

The phenomenon of long-period sunspot oscillations with periods from several tens to a thousand minutes is studied using data on the magnetic field strength and sunspot coordinates obtained based on the SOHO MDI data. It has been indicated that oscillations of the sunspot magnetic field strength are related to relative and absolute horizontal oscillation modes, as a result of which certain limitations are imposed on the interpretation of the phenomenon.     

Properties of the sunspot latitudinal distribution skewness

The properties of the sunspot latitudinal distributions related to skewness have been studied based on the data of the extended Greenwich catalog for 1874–2011. The results of the performed analysis indicate that a significant skewness is present in most annual latitudinal distributions of the sunspot index. In this case, the distribution skewness increases near the 11-year cycle maximum phase. An increase in the sunspot group number is also accompanied by an increase in skewness. In particular, when the sunspot index is large, the number of groups located below midlatitudes is mostly larger than the number of groups above these latitudes and this imbalance increases with increasing total sunspot activity level. In medium and large 11-year cycles, the average distribution skewness for a cycle is always positive and its value is related to the cycle amplitude. This results agree with the theoretical models of the 11-year cycle, where the specific features of the low-latitude meridional circulation are related to the sunspot activity level.     

The sunspot cycle and solar and lunar daily variations inH

Summary Results of sunspot cycle influence on solar and lunar ranges at a low latitude station, Alibag, outside the equatorial electrojet belt, show that the sunspot cycle association in solar ranges is three times that of the lunar ranges in thed- andj-seasons. This is in general agreement with the earlier results for non-polar latitude stations. The association with sunspot number of individual lunar amplitudes is greatest for lunar semidiurnal harmonic in thej-season. During this season, the sunspot cycle influence on lunar variations is more than that on solar variations, thereby indicating that the lunar current is situated at a level more favourable for sunspot cycle influence than the level of the current associated with solar variations. With the increase in solar activity a shift appears in the times of maxima of semidiurnal lunar variation towards a later lunar hour ine- andj-seasons and in the year.     

Prediction of sunspot number amplitude and solar cycle length for cycles 24 and 25

The prediction of solar activity strength for solar cycles 24 and 25 is made on the basis of extrapolation of sunspot number spectral components. Monthly sunspot number data during the 1850–2007 interval (solar cycles 9–23) are decomposed into several levels and searched for periodicities by iterative regression in each level. For solar cycle 24, the peak is predicted in November 2013 with a sunspot number of 113.3. The cycle is expected to be weak, with a length of 133 mo (months) or 11.1 yr. The sunspot number maximum in cycle 25 is predicted to occur in April 2023 with a sunspot number 132.1 and a solar cycle length of 118 mo or 9.8 yr. Thus, solar cycle 24 is predicted to have an intensity 23% lower than cycle 23, and cycle 25 will be 5% lower than cycle 23.     

Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles

Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r) between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.     

Prediction of cycle 24 based on information about solar activity during the last 10 000 years

The average and maximal numbers of sunspot groups in the approaching solar cycle (cycle 24) have been predicted using paleoastrophysical information about solar activity during the last more than 10000 years. The linear and nonlinear prediction methods have been applied. It has been indicated that, from the standpoint of solar paleoastrophysics, the next cycle will most probably be average: the number of sunspot groups at a maximum will reach 68–101. The probability that cycle 24 will be powerful (more than 160 sunspot groups), which was predicted by some researchers, is low (not higher than 2%).     

Relations of latitudinal characteristics of sunspot groups to the 11-year cycle amplitude at different phases

Using sunspot data for cycles 12 to 23, we have investigated relations of some latitude characteristics of sunspot groups to the 11-year cycle amplitude at different phases. We have revealed a high correlation (with correlation coefficients >0.9) between the middle latitude of sunspot groups at phases of rise, maximum, and decay, on the one hand, and the amplitude of the corresponding cycle, on the other hand. We have shown that the maxima of the velocity of the motion of the sunspot formation zone to the equator have a special physical meaning: the rise phase of the 11-year cycle is characterized by significant correlations between the cycle amplitude and the maximum for the lowest boundary, and the cycle decay phase is characterized by the same maximum for the highest boundary. We have built equations allowing one to determine the amplitude of the 11-year cycle on the basis of data on the given latitudinal characteristics of sunspots groups.     

Comparative Analysis of the Catalog of Individual Sunspots Based on Data from Kislovodsk Mountain Astronomical Station

Geomagnetism and Aeronomy - A comparative analysis of sunspot sizes in sunspot groups was performed. For this analysis, we used the database of characteristics of individual sunspots and pores...     

太阳黑子活动与新疆强震活动的关系

使用1900年以来的太阳黑子数据,统计分析了其与新疆地区MS≥6.6强震的关系。结果显示：新疆地区69%的MS≥6.6和86%的MS≥7的地震,发生在黑子数月均值≤35的时段内。以黑子数月均值≤20和≤35的时段作为MS≥6.6强震的预测指标,报准率分别为71%和64%;以黑子数月均值≤35的时段作为MS≥6.6强震的预测指标,报准率为69%。R值评分检验表明,上述预测指标是有效的。最后使用这些统计关系和指标对新疆未来几年发生强震的可能性作了估计。     

Characteristics of sunspot longitudinal distribution and their correlation with solar activity in pre-Greenwich data

We study and compare characteristics of the sunspot group latitude distribution in two catalogs: extended Greenwich (1874–2014) and Schwabe (1825–1867) (Arlt et al., 2013). We show that both datasets reveal similar correlations between the latitude and amplitude characteristics of the 11-year cycle: the latitude dispersion correlates with the current activity and the sunspot mean latitude at the cycle’s maximum is proportional to its amplitude. This agrees with the conclusions drawn in (Ivanov et al., 2011; Ivanov and Miletsky, 2014) for the Greenwich catalog. We show that the latitude properties of the sunspot distribution are much more tolerant to gaps in observational data than traditional amplitude indices of activity. Therefore, the discovered correlations can be used for estimation of the observation quality and independent normalization of the activity levels in spotty pre-Greenwich data. We exemplified this using the Schwabe catalog. In addition, we show that the first part of the Schwabe data probably contains errors in sunspot latitudes, which lead to overestimation of the sunspot latitude dispersions.     

Long-term variations in sunspot characteristics

Relative variations in the number of sunspots and sunspot groups in activity cycles have been analyzed based on data from the Kislovodsk Mountain Astronomical Station and international indices. The following regularities have been established: (1) The relative fraction of small sunspots decreases linearly and that of large sunspots increase with increasing activity cycle amplitude. (2) The variation in the average number of sunspots in one group has a trend, and this number decreased from ～12 in cycle 19 to ～7.5 in cycle 24. (3) The ratio of the sunspot index (Ri) to the sunspot group number index (G _gr) varies with a period of about 100 years. (4) An analysis of the sunspot group number index (G _gr) from 1610 indicates that the Gnevyshev-Ohl rule reverses at the minimums of secular activity cycles. (5) Ratio of the total area to area of Ssp/Sum nuclei has long-term variation with a period approximately 8 cycles. Minimum ratio falls on 16–17 cycles of activity. (6) It has been indicated that the magnetic field intensity and sunspot area in the current cycle are related to the amplitude of the next activity cycle.     

第23太阳周黑子相对数的峰值、峰期以及结束期的预测

Two parameters,the smoothed sunspot numbers in the eleventh month during rising phase of the current cycle and the length month of the minimum period (R<14),are selected to predict the maximum-value of sunspot number of cycle 23 in this paper. The predicted maximum-values of smoothed sunspot number are 115<Ri<149 and 114<Ri<146 also predicted by statistical method. The peak-time will be from September,1999 to March,2000,and the end-time will be from August,2006 to April,2008.     

Reconstruction of sunspot characteristics for 1853–1879

The Carrington (1853?C1861) and Sp?rer (1861?C1879) catalogs of sunspot drawings have been digitized. In the Carrington catalog, 9831 sunspots and 4946 umbrages were detected on daily drawings and 3762 sunspots and 1730 umbrages on synoptic maps. This allowed us to reconstruct the characteristics of 3069 sunspot groups for the period from November 9, 1853, to April 1, 1861. In the Sp?rer catalogs, 12402 sun-spots and about 5000 umbrages were detected for 1861?C1879. Sunspots and umbrages were detected semiautomatically, a heliographic grid was plotted, and sunspot groups were formed when the images were processed. The digitized data made it possible to determine the coordinates, areas, relative position, and other geometric parameters of individual sunspots, umbrages, and sunspot groups. These data make it possible to study in detail the fine structure at the end of cycle 9 and in cycles 10 and 11. An electron database of the detected structures has been created.