太阳黑子磁场磁极性指标的构建及其周期性分析

太阳黑子磁场磁极性指数作为衡量太阳磁场磁性变化的重要指标,在研究太阳活动方面发挥重要作用．本文根据1749—2019年的太阳黑子磁场磁极性指数时间序列（SMFPI）,利用索周法获得其周期性特征并成功构建了太阳黑子磁场磁极性指标．通过对近270年太阳黑子磁极性数据的索周分析,发现存在显著的准2216年、1820年的主周期规律,其中以准2216年的周期性最强．对太阳黑子磁场磁极性指标进行数值模拟,重建了近270年的太阳黑子磁场磁极性时间序列;通过对比太阳黑子磁场极性的重建数据和观测数据,发现构建的太阳黑子磁场磁极性指标能够准确反映太阳黑子磁场磁极性的变化规律．利用功率谱分析和小波分析方法,分别对太阳黑子磁场磁极性观测数据和重建数据进行周期性分析：功率谱分析表明两组数据均具有平均2254年的主周期和1813年的次周期;小波分析表明两组数据在1749—2019年期间近270年整个时段内具有17～435年的周期区间．因此,两种周期分析结果保持良好的一致性,也同索周分析呈现的结果保持一致．太阳黑子磁场磁极性指标能够有效重建太阳黑子磁场磁性时间序列,准确反映太阳活动的变化趋势;进而为研究...     

地磁场长期变化和日长十年尺度变化的周期特征

根据历史地磁场模型GUFM1、第10代国际参考地磁场（IGRF10）模型和日长资料,采用小波变换方法,分析了地磁场磁矩、能量、西向漂移等参数的长期变化和日长十年尺度变化的周期分量及其时变特征.结果表明,1800～2005年期间,偶极子磁场长期变化有82年和48年准周期分量,它们与日长变化的周期没有直接关系.非偶极子磁场参数的长期变化与日长变化有66年和32年准周期分量,66年准周期比32年准周期强.在66年准周期分量,西向漂移比日长变化超前8.8年,非偶极子磁场能量比日长变化滞后15.6年.日长十年尺度波动和地磁场长期变化的起源不存在因果关系.     

太阳磁场磁性指数异常变化对南北半球中纬度气候的影响

本文参照太阳黑子相对数特征建立了太阳黑子磁场磁性指数时间序列. 大气温度场谱分析结果显示,南北半球中纬度平流层和对流层大气温度场普遍存在22年变化周期. 分析认为,大气温度场的22年变化周期是太阳活动22年磁性周期所激发.     

太阳黑子相对数最强周期的小波分析

利用小波变换,分析了1749年以来每个太阳活动周太阳黑子相对数的最强周期以及第1～22太阳活动周的最强周期. 分析结果表明,在第5和第6个太阳活动周,太阳黑子相对数最强的周期分别为64.67年和69.31年;在第13～15太阳活动周,太阳黑子相对数的最强周期分别为98.02年,105.06年和105.06年. 在第1～22太阳活动周中,太阳黑子相对数最强的周期是128个月,约10.67年,其他太阳活动周的最强周期介于9.29～11.43年之间. 本文最后给出了128个月周期的幅度随时间的变化.     

短中时间尺度上的气温变化和太阳辐射之间的关系研究

探讨气温变化的时空特征及其产生原因越来越成为当代大气科学关注的焦点.过去的大多研究揭示了长时间尺度上的气候变化受太阳辐射的影响情况.本文采用经验模态分解的方法,通过识别气温和太阳黑子变化中的特征时间尺度,分析了短中时间尺度上南京市与石家庄市气温和太阳辐射之间的关系,得到了吻合以前实证结果的太阳黑子11a的准周期成分等,在气温变化中也找到了相似于太阳黑子5.5和11a的准周期成分,但是相关性分析及检验某一模态信号是否为随机信号的验证分析同时说明相似周期成分之间并不相关.在95%的置信度下,南京市和石家庄市气温变化中确实存在不少短周期波动,它们和太阳辐射之间并不存在直接的相关关系,而且南京市气温3.1a的中周期波动也吻合前人的研究成果.     

利用EMD方法提取地磁A_p指数周期分量

利用EMD和小波对试验信号进行分解比较,结果表明EMD方法能够更加真实的再现数据本身的频谱分量和对应幅度．利用EMD方法对1932年~2006年地磁Ap指数月均值进行了分解,分别得到一系列模式和一个趋势项．其中可能包含了6个月周期分量,准1年周期分量,QBO（准两年震荡）分量,准5年周期分量,准11年周期分量和22年Hale周分量等．地磁活动Ap指数与太阳黑子数都有着11年周期变化,我们比较发现Ap指数11年周期分量极值出现要比太阳黑子数11年周期分量极值出现平均滞后1~2年．     

太阳活动Hallstatt周期及太阳活动周强弱变化的预测

基于之前创建的行星会合指数运动学方程,发现太阳质心具有平均准22年向太阳系质心靠近(有时近似重合)的轨道运动周期.在整个太阳系角动量守恒的前提下,推出太阳自转角动量和太阳绕转角动量之和守恒.二者角动量转换造成太阳自转角动量变化和太阳绕转角动量变化具有互为反向的准22年变化规律.太阳自转角速度变化(dω/dt)图像与太阳黑子磁性指数图像具有一致对应关系,这种对应关系可以从物理机制上对太阳活动周相位变化和太阳活动强弱变化进行解释,这为预测太阳活动提供了一种有效方法.本研究为太阳活动替代性指标指代的双世纪周期和2403年哈尔斯塔(Hallstatt)周期规律找到了理论根据.     

太阳磁场方向变化对于地球大气温度异常变化的意义

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MI(Magnetic Index)时间序列.分析表明：太阳活动磁性周期平均长度为222年,但是每个周期长度是不相等的;多数情况周期短时磁性指数较大,对应太阳活动水平强;周期变长时磁性指数较小,对应太阳活动水平较弱;太阳黑子磁场磁性指数序列也具有80～90年的世纪周期. 进一步研究指出,太阳黑子磁场磁性指数曲线由极小值升至极大值时期,太阳磁场南向,行星际磁场磁力线与地磁场磁力线重联,此时磁层为开磁层,太阳风将携带大量等离子体从向阳面进入地球磁层,从而使输入的动量、能量和物质大幅度增加,与北半球对流层增温时期对应;太阳黑子磁场磁性指数曲线由极大值下降至极小值时期,太阳磁场北向,与磁层顶地磁场同向,行星际磁场不会与地磁场发生重联,此时磁层为闭磁层,这种情况下,只有少数带电粒子能够穿越磁力线进入地球磁层,与北半球对流层降温时期对应.     

极移振幅主要周期分量的时变特征

用JPL近年发布的地极坐标序列求得1893―1998年间极移的振幅序列,用最大熵谱分析方法求得了该资料序列包含的一些周期的参数,并利用小波变换方法分析讨论了其中的主要周期的变化.结果表明,极移振幅变化中存在着约6.5年和约40年的主要周期,且它们均具有一定程度的时变性.因此,在研究讨论极移与一些地球物理现象和自然灾害现象的关系时,应特别注意极移振幅中主要周期的时变特征.     

太阳活动11年周期对气象参数影响

利用多种资料研究了太阳活动11年周期对全球气温、风场、海表温度(SST)的影响,结果表明:(1)在第21、22太阳活动周,中低纬对流层顶以上大气温度变化具有类似太阳黑子变化的11年左右周期,相对于太阳黑子数,气温变化具有1～2年的延迟性;相对于太阳活动低年,200～10 hPa大气在太阳活动高年整层增温,以赤道低纬地区...     

Solar activity secular cycles

Long-term variations in solar activity secular cycles have been studied using a method for the expansion of reconstructed sunspot number series Sn(t) for 11400 years in terms of natural orthogonal functions. It has been established that three expansion components describe more than 98% of all Sn(t) variations. In this case, the contribution of the first expansion component is about 92%. The averaged form of the 88year secular cycle has been determined based on the form of the first expansion coordinate function. The quasi-periodicities modulating the secular cycle have been revealed based on the time function conjugate to the first function. The quasi-periodicities modulating the secular cycle coincide with those observed in the Sn(t) series spectrum. A change in the secular cycle form and the time variations in this form are described by the second and third expansion components, the contributions of which are about 4 and 2%, respectively. The variations in the steepness of the secular cycle branches are more pronounced in the 200-year cycle, and the secular cycle amplitude varies more evidently in the 2300-year cycle.     

Long-term variations of the solar-geomagnetic correlation,total solar irradiance,and northern hemispheric temperature (1868–1997)

Time series for annual means of sunspot numbers, aa-indices of geomagnetic activity and annual numbers of 3-h time intervals with different values of aa-indices (aa≤4 and aa≥30) from 1868 to 1997 have been examined by the method of running-window cross-correlation analysis. It has been found that the solar-geomagnetic correlation varies over time. In particular, long-term variations of the 23-year running correlation appear to have a quasi periodicity of about 40–50 years, superposed on a linear trend, where the trend describes a general decrease of the 23-year running-window correlation between 1868 and the present. Long-term variations of the solar-geomagnetic correlation may result from the quasi-periodic fluctuations of the time lag of geomagnetic indices relative to sunspot numbers, superposed on an upward linear trend of time lag. Secular variations of the northern hemisphere land-air surface temperature anomalies and two solar indices that are potential proxy measures for the total solar irradiance (i.e., the length of the sunspot cycle and the Hoyt and Schatten (Hoyt, D.V., Schatten, K.V., 1993. Journal of Physical Research 98, 18,895–18,906.) composite index) have been compared with the long-term variations of the solar-geomagnetic correlation. The extremum points (points where the derivative vanishes to zero) of these variations are found to occur contemporaneously during the periods of low solar-geomagnetic correlation, suggesting, perhaps, that the long-term variations of solar-geomagnetic correlation are due to some long-term processes on the Sun and that they have a measurable effect on the Earth.     

The dynamic relation between activities in the Northern and Southern solar hemispheres

The north–south (N/S) asymmetry of solar activity is the most pronounced phenomenon during 11-year cycle minimums. The goal of this work is to try to interpret the asymmetry as a result of the generalized synchronization of two dynamic systems. It is assumed that these systems are localized in two solar hemispheres. The evolution of these systems is considered in the topological embeddings of a sunspot area time series obtained with the use of the Takens algorithm. We determine the coupling measure and estimate it on the time series of daily sunspot areas. The measurement made it possible to interpret the asymmetry as an exchangeable dynamic equation, in which the roles of the driver–slave components change in time for two hemispheres.     

Time evolution of cosmic-ray intensity and solar flare index at the maximum phase of cycles 21 and 22

Analysis of the time series into trigonometric series allows the investigation of cosmic-ray (CR) intensity variations in a range of periodicities from a few days to 1 year. By this technique the amplitude and the phase of all observed fluctuations can be given. For this purpose, daily CR intensity values recorded at Climax Neutron Monitor station for the time intervals 1979–1982 and 1989–1991, which correspond to the epochs of maximum activity for solar cycles 21 and 22, respectively, have been studied. The data analysis revealed the occurrence of new periodicities, common or not, in the two solar maxima. A search of our results was done by a power spectral analysis determining independently possible systematic periodic or quasi-periodic variations. Based on the fact that during these maxima the CR intensity tracks the solar flare index better than the sunspot number, the same analysis was performed on these data, which are equivalent to the total energy emitted by the solar flares. Both analyses result in periodicities with different probability of occurrence in different epochs. Occurrence at peaks of 70, 56, 35, 27, 21 and 14- days were observed in all time series, while the periods of 140–154 and 105 days are reported only in the 21st solar maximum and are of particular importance. All of the short-term periods except of those at 27 and 154-days are recorded for first time in CR data, but they had already been observed in the solar activity parameters. Moreover, each parameter studied here has a very different power spectrum distribution in periods larger than 154 days. The possible origin of the observed variations in terms of the CR interaction in the upper atmosphere and the solar cavity dynamics is also discussed here.     

On the prediction of solar activity using different neural network models

Accurate prediction of ionospheric parameters is crucial for telecommunication companies. These parameters rely strongly on solar activity. In this paper, we analyze the use of neural networks for sunspot time series prediction. Three types of models are tested and experimental results are reported for a particular sunspot time series: the IR5 index.     

Transition of solar cycle length in association with the occurrence of grand solar minima indicated by radiocarbon content in tree-rings

In this paper, we review the variation of the 11-year solar cycle since the 15th century revealed by the measurement of radiocarbon content in single-year tree-rings of Japanese cedar trees. Measurements of radiocarbon content in absolutely dated tree-rings provide a calibration curve for accurate dating of archaeological matters, but at the same time, enable us to examine the variations of solar magnetic activity in the pre-historical period. The Sun holds several long-term quasi-cyclic variations in addition to the fundamental 11-year sunspot activity cycle and the 22-year polarity reversal cycle, and it is speculated that the property of the 11-year and the 22-year solar cycle varies in association with such long-term quasi-cycles. It is essential to reveal the details of solar variations around the transition time of solar dynamo for illuminating the mechanisms of the long-term solar variations. We therefore have investigated the property of the 11-year and 22-year cycles around the two grand solar minima; the Maunder Minimum (1645–1715 AD) and the Spoerer Minimum (1415–1534 AD), the periods of prolonged sunspot minima. As a result, slight stretching of the “11-year” and the “22-year” solar cycles was found during these two grand solar activity minima; continuously during the Maunder Minimum and only intermittently during the Spoerer Minimum. On the contrary, normal or slightly shortened 11-year cycles were detected during the interval period of these two minima. It suggests the inverse correlation between the solar cycle length and solar magnetic activity level, and also the change of meridional flow during the grand solar activity minima. Further measurements for the beginning of the grand solar minima will provide a clue to the occurrence of such prolonged sunspot disappearance. We also discuss the effect of solar variations to radiocarbon dating.     

Variable Solar Forcing and Climate Changes

Numerous studies of interrelations between solar activity and global climate changes report contradictory conclusions. The topic as such is too complex, and manifestations of the studied relationship appear to differ in time and space, and sometimes are even of the opposite sense, In this study the data on air temperature and precipitation totals from Hurbanovo, one of the oldest meteorological observatories in Europe, are used to study their evolution within the interval 1871–1995, covering solar cycles 12–22, The variability of the meteorological elements mentioned is compared with that of the sunspot number and aa index of geomagnetic activity. The sensitivity of climate changes to variable solar forcing is presented as a comparison of extreme (maximum/minimum) activity conditions. Harmonic components with periods close to the length of the solar secular and solar magnetic cycles were found in climate evolution profiles.     

On the 18-day quasi-periodic oscillation in the ionosphere

The presence and persistence of an 18-day quasi-periodic oscillation in the ionospheric electron density variations were studied. The data of lower ionosphere (radio-wave absorption at equivalent frequency near 1 MHz), middle and upper ionosphere (critical frequencies f₀E and f₀F2) for the period 1970–1990 have been used in the analysis. Also, solar and geomagnetic activity data (the sunspot numbers Rz and solar radio flux F10.7 cm, and a_N index respectively) were used to compare the time variations of the ionospheric with the solar and geomagnetic activity data. Periodogram, complex demodulation, auto- and cross-correlation analysis have been used. It was found that 18-day quasi-periodic oscillation exists and persists in the temporal variations of the ionospheric parameters under study with high level of correlation and mean period of 18–19 days. The time variation of the amplitude of the 18-day quasi-periodic oscillation in the ionosphere seems to be modulated by the long-term solar cycle variations. Such oscillations exist in some solar and geomagnetic parameters and in the planetary wave activity of the middle atmosphere. The high similarities in the amplitude modulation, long-term amplitude variation, period range between the oscillation of investigated parameters and the global activity of oscillation suggests a possible solar influence on the 18-day quasi-periodic oscillation in the ionosphere.     

Solar-Terrestrial Signal Record in Tree Ring Width Time Series from Brazil

This work investigates the behavior of the sunspot number and Southern Oscillation Index (SOI) signal recorded in the tree ring time series for three different locations in Brazil: Humaitá in Amaz?nia State, Porto Ferreira in S?o Paulo State, and Passo Fundo in Rio Grande do Sul State, using wavelet and cross-wavelet analysis techniques. The wavelet spectra of tree ring time series showed signs of 11 and 22?years, possibly related to the solar activity, and periods of 2–8?years, possibly related to El Ni?o events. The cross-wavelet spectra for all tree ring time series from Brazil present a significant response to the 11-year solar cycle in the time interval between 1921 to after 1981. These tree ring time series still have a response to the second harmonic of the solar cycle (5.5?years), but in different time intervals. The cross-wavelet maps also showed that the relationship between the SOI x tree ring time series is more intense, for oscillation in the range of 4–8?years.