太阳黑子数及Ap指数周期变化特征的小波分析

应用Morlet小波变换方法从多个变化尺度上对1932—2000年的太阳黑子数及Ap指数的变化特征进行分析．(1)太阳黑子数存在准11年、准32年的周期变化特征及Ap指数存在准32年、准11年、准6个月、准27天和准13．9天的周期变化特征；(2)太阳黑子数及Ap指数有着相似的准11年周期变化，但Ap指数极值的出现要比太阳黑子数极值出现滞后1—2年；(3)Ap指数准27天的周期变化在太阳黑子活动高、低年不同，在太阳活动低年，Ap指数有着较稳定的准27天周期变化，但在太阳活动高年，27天的周期变化几乎消失，这种周期变化的消失和出现时间可在Morlet小波变换图中体现出来。     

Temporal variation and asymmetry of sunspot and solar plage types from 1930 to 1936

Using the recently converted to digital format heliophysics catalogues of the Ebro Observatory published in the 1930s, we analyse simultaneously the temporal variation and asymmetry of two different solar structures located at different layers of the solar atmosphere: sunspots and solar plages. In particular, we do the research for all the types of sunspots and plages, including the daily and relative frequencies over the solar cycle. The data were catalogued using the sunspot Cortie classification and a solar plage classification scheme proposed by the Ebro Observatory, which group the phenomena by size and shape. For all types of both sunspots and plages, we observe a decrease in their frequency up to the end of solar cycle 16 and an increase over the beginning of solar cycle 17. Furthermore, we note that small sunspot groups are more likely to happen than bigger groups, although single big spots dominate near the solar minimum. The daily frequency of solar plage occurrences shows that there is not a dominance of compact or scattered solar plages. The North-South occurrence distribution of every type in both sunspots and solar plages shows an asymmetry during the solar cycle: in its declining phase, such asymmetry is directed to the north, while in the beginning of a new cycle is directed to the south.     

Variations of mid-term periodicities in solar activity physical phenomena

In this work we make an analysis of significant periodicities shown by phenomena linked to solar activity such as coronal hole area, radio emission in the 10.7 cm band and sunspots. We use the wavelet method that gives information in the frequency and time domains. Of particular interest are the mid-term periodicities (1–2 yrs). Over the whole period, coronal holes and radio variations show an important annual variation and a quasi-biannual periodicity. The increase in these variations is most important around the years of maximum solar activity. When the time series are separated in low and high frequencies, the latter are modulated by the general solar cycle. Although somewhat shifted in frequency, these periodicities might well correspond with those found in cosmic ray intensity, solar magnetic flux and other terrestrial and interplanetary phenomena as a wavelet coherence analysis of these series with the solar magnetic flux reveals.     

Solar wind dependence of the Pc1 wave activity

There are a host of factors influencing the excitation of Pc1 geomagnetic pulsations, which are ULF waves in the frequency range between 0.2 and 5 Hz. We have studied carefully the dependence of the pearl-type Pc1 activity at Sodankylä, Finland (L = 5.1) on the plasma density N in front of the magnetosphere, the bulk velocity V of the solar wind, and the intensity B of the IMF. The result is as follows: high values of N and reduced values of V are favorable to appearance of Pc1, whereas the dependence of Pc1 activity on B is practically absent. We also show that the probability of Pc1 occurrence decreases with the interplanetary electric field, and increases with solar wind impact pressure and with the plasma to magnetic pressure ratio “beta”.     

Interplanetary shocks and geomagnetic activity during solar maximum (2000) and solar minimum (1995–1996)

Plasma and magnetic field parameter variations through fast forward interplanetary shocks were correlated with the peak geomagnetic activity index Dst in a period from 0 to 3 days after the shock, during solar maximum (2000) and solar minimum (1995–1996). Solar wind speed (V) and total magnetic field (B_t) were the parameters with higher correlations with peak Dst index. The correlation coefficients were higher during solar minimum (r² = 56% for V and 39% for B_t) than during solar maximum (r² = 15% for V and 12% for B_t). A statistical distribution of geomagnetic activity levels following interplanetary shocks was obtained. It was observed that during solar maximum, 36% and 28% of interplanetary shocks were followed by intense (Dst  −100 nT) and moderate (−50  Dst < −100 nT) geomagnetic activity, whereas during solar minimum 13% and 33% of the shocks were followed by intense and moderate geomagnetic activity. It can be concluded that the upstream/downstream variations of V and B_t through the shocks were the parameters better correlated with geomagnetic activity level, and during solar maximum a higher relative number of interplanetary shocks can be followed by intense geomagnetic activity than during solar minimum. One can extrapolate, for forecasting goals, that during a whole solar cycle a shock has a probability of around 50% to be followed by intense/moderate geomagnetic activity.     

高层大气原子氧的半年周变

地球高层大气成分的长期变化受太阳黑子周、太阳活动程度和地磁活动程度等诸多因子所控制．本文利用国外有关高层大气成分的数据,分别讨论受上述控制因子影响的高层大气成分长期变化,讨论范围仅限原子氧半年周期变化．选用LDEF在轨飞行器1984年4月—1990年1月高度470km附近的长期资料进行统计分析,结果表明,高度470km附近原子氧在年平均太阳黑子数＜20、太阳活动程度相对低而平稳期间,半年周期的变化尤为明显,相对变幅约为40％—60％、井随平均太阳黑子数增加而增大．而年平均太阳黑子数峰值的1989年期间（＞120）,半年变化的相对变幅可达87％左右．     

Solar and interplanetary precursors of geomagnetic storms in solar cycle 23

Estimating the magnetic storm effectiveness of solar and associated interplanetary phenomena is of practical importance for space weather modelling and prediction. This article presents results of a qualitative and quantitative analysis of the probable causes of geomagnetic storms during the 11-year period of solar cycle 23: 1996–2006. Potential solar causes of 229 magnetic storms (Dst ? −50 nT) were investigated with a particular focus on halo coronal mass ejections (CMEs). A 5-day time window prior to the storm onset was considered to track backward the Sun’s eruptions of halo CMEs using the SOHO/LASCO CMEs catalogue list. Solar and interplanetary (IP) properties associated with halo CMEs were investigated and correlated to the resulting geomagnetic storms (GMS). In addition, a comparative analysis between full and partial halo CME-driven storms is established. The results obtained show that about 83% of intense storms (Dst ? −100 nT) were associated with halo CMEs. For moderate storms (−100 nT < Dst ? −50 nT), only 54% had halo CME background, while the remaining 46% were assumed to be associated with corotating interaction regions (CIRs) or undetected frontside CMEs. It was observed in this study that intense storms were mostly associated with full halo CMEs, while partial halo CMEs were generally followed by moderate storms. This analysis indicates that up to 86% of intense storms were associated with interplanetary coronal mass ejections (ICMEs) at 1 AU, as compared to moderate storms with only 44% of ICME association. Many other quantitative results are presented in this paper, providing an estimate of solar and IP precursor properties of GMS within an average 11-year solar activity cycle. The results of this study constitute a key step towards improving space weather modelling and prediction.     

中等磁暴太阳周分布的统计研究

依据实际观测的中等磁暴数据,统计分析了中等磁暴的太阳周分布.分析结果表明,在一个太阳活动周内,每年中等磁暴随时间的变化出现多个峰值,其中,最大峰值均出现在太阳活动周的下降段,即中等磁暴的峰值比太阳黑子数平滑年均值的峰值要滞后,滞后的时间为2～3年.超过70%的中等磁暴出现在太阳活动周的下降段,这表明绝大多数中等磁暴出现在太阳活动周的下降段.通过对中等磁暴平滑月均值与太阳黑子数平滑月均值相位差的计算分析发现,中等磁暴峰值出现的时间比太阳黑子数峰值出现的时间要滞后,不同太阳活动周中等磁暴峰值出现的时间与太阳黑子数峰值时间滞后的程度不同.      

Evolution of the solar corona from solar maximum to minimum

A study on solar coronal activities related to the 11-year activity cycle is presented from the Yohkoh soft X-ray observations. Yohkoh was launched in August 1991, just after the solar maximum of the cycle 22 and continues to observe the Sun in the declining phase of the magnetic activity cycle toward the solar minimum. The soft X-ray flux from the whole Sun in the declining phase essentially decreases with the size of active regions. The X-ray intensity in quiet regions in the declining phase decreases with the magnetic flux observed at the photosphere. The whole-Sun soft X-ray flux does not monotonically decrease, but there are periodic enhancements of the flux with about a one-year interval. The activity appears as bright clusters in the butterfly diagram of the soft X-ray intensity and corresponds to the emergence of complexes of activity in the sunspot zones. The high-latitude activity is also studied, and we find that the X-ray intensity of high-latitude regions fluctuates with time scale of about one year.     

Geomagnetic activity associated with magnetic clouds,magnetic cloud-like structures and interplanetary shocks for the period 1995–2003

Using nine years (1995–2003) of solar wind plasma and magnetic field data, solar sunspot number, and geomagnetic activity data, we investigated the geomagnetic activity associated with magnetic clouds (MCs), magnetic cloud-like structures (MCLs), and interplanetary shock waves. Eighty-two MCs and one hundred and twenty-two MCLs were identified by using solar wind and magnetic field data from the WIND mission, and two hundred and sixty-one interplanetary shocks were identified over the period of 1995–2003 in the vicinity of Earth. It is found that MCs are typically more geoeffective than MCLs or interplanetary shocks. The occurrence frequency of MCs is not well correlated with sunspot number. By contrast, both occurrence frequency of MCLs and sudden storm commencements (SSCs) are well correlated with sunspot number.     

地磁Ap指数滞后太阳周循环分析

把1932-2006年地磁Ap指数12个月流动均值分解成为(Ap)R和(Ap)I.其中(Ap)R为太阳黑子数R的线性函数,与太阳黑子数R相位相同,可能对应于日冕物质抛射(CME)等地磁控制因素. (Ap)I分量与太阳黑子数R相位相差约180°,该分量可能对应于极冕洞变化(从太阳峰年开始,由日面极区逐渐向赤道延伸).以地磁Ap指数与太阳黑子数R滞后非常严重的第20太阳周为例,证实了(Ap)I分量与极冕洞向赤道延伸循环变化相对应.因此极冕洞循环变化可能是导致地磁扰动指数与太阳周循环相位不一致,出现滞后现象的一个十分重要原因.      

海口站与Huancayo站扩展F的差异

本文统计分析了我国海口站太阳黑子高年和低年的扩展F的资料,得出了该站扩展F的出现率随地方时、季节和太阳活动周期的某些变化规律并与Huancayo站扩展F的资料进行了比较,指出了两站扩展F的差异。      

Comparison of heliospheric conditions near the earth during four recent solar maxima

Statistical properties of the daily averaged values of the solar activity (sunspot numbers, total solar irradiance and 10.7 cm radio emission indices), the solar wind plasma and the interplanetary magnetic field parameters near the Earth’s orbit are investigated for a period from 1964 to 2002 covering the maxima of four solar cycles from 20th to 23rd. Running half-year averages show significant solar cycle variations in the solar activity indices but only marginal and insignificant changes in comparison with background fluctuations for heliospheric bulk plasma and magnetic field parameters. The current 23rd cycle maximum is weaker than 21st and 22nd maxima, but slightly stronger than 20th cycle in most of solar and heliospheric manifestations.     

Essential features of long-term changes of areas and diameters of sunspot groups in solar activity cycles 12–24

We analyze the Greenwich catalog data on areas of sunspot groups of last thirteen solar cycles. Various parameters of sunspots are considered, namely: average monthly smoothed areas, maximum area for each year and equivalent diameters of groups of sunspots. The first parameter shows an exceptional power of the 19th cycle of solar activity, which appears here more contrastively than in the numbers of spots (that is, in Wolf’s numbers). It was found that in the maximum areas of sunspot groups for a year there is a unique phenomenon: a short and high jump in the 18th cycle (in 1946–1947) that has no analogues in other cycles. We also studied the integral distributions for equivalent diameters and found the following: (a) the average value of the index of power-law approximation is 5.4 for the last 13 cycles and (b) there is reliable evidence of Hale's double cycle (about 44?years). Since this indicator reflects the dispersion of sunspot group diameters, the results obtained show that the convective zone of the Sun generates embryos of active regions in different statistical regimes which change with a cycle of about 44?years.     

Even–odd cycle parity in complexity of hemispheric sunspot activity

We have used the Lempel–Ziv measure to describe the complexity in sunspot activity during the solar cycles 18–23. In particular, we examined the time series of daily sunspot numbers in the northern and southern hemispheres in each of the six cycles and calculated the Lempel–Ziv complexity (LZC) value for each time series. Our results indicate that in the even cycles, the LZC values of the sunspot numbers in the two hemispheres are very close to each other, whereas in the odd cycles they differ significantly between the two hemispheres. We also find that within each hemisphere the LZC varies from cycle to cycle. This even–odd cycle parity reflects the variations in inter-hemispheric strengths of the solar magnetic field leading to different temporal distributions of sunspots in the two hemispheres. The degree of complexity may influence the predictability of sunspot activity in the two hemispheres during the various cycles. Although the physical implication of the results is not clear, these results may stimulate new ideas into modeling the complex dynamics of the solar dynamo.     

Variations of the radiation dose onboard Mir station

Dose variations, associated with the 11-year solar activity cycle, seasonal variations of particle fluxes in the Earth's radiation belts at the station orbit, and solar proton events are studied, using prolonged measurements of radiation doses inside orbital station Mir. Daily averages of radiation doses during the declining phase of the 22^nd solar cycle and during transition to the 23^rd solar activity cycle reached very large values for astronauts and significantly exceed the values calculated according to existing models.     

Correlation between sunspots and interplanetary shocks measured by ACE during 1998–2014 and some estimations for the 22nd solar cycle and the years between 2015 and 2018 with artificial neural network using the Cavus 2013 model

The Advanced Composition Explorer (ACE) spacecraft has measured 235 solar-based interplanetary (IP) shock waves between the years of 1998–2014. These were composed of 203 fast forward (FF), 6 slow forward (SF), 21 fast reverse (FR) and 5 slow reverse (SR) type shocks. These data can be obtained from the Interplanetary Shock Database of Harvard-Smithsonian Centre for Astrophysics. The Solar Section of American Association of Variable Star Observers (AAVSO) is an organization that counts the number of the sunspots. The effects of interplanetary shock waves on some physical parameters can be computed using a hydrodynamical model. There should be some correlations between these effects and the sunspot variations. The major objective of this paper is twofold. The first one is to search these correlations with sunspots given in the database of AAVSO. As expected, high correlations between physical parameters and sunspots have been obtained and these are presented in tables below. The second objective is to make an estimation of these parameters for the 22nd solar cycle and the years between 2015 and 2018 using an artificial neural network. Predictions have been made for these years where no shock data is present using artificial intelligence. The correlations were observed to increase further when these prediction results were included.     

Sun–Earth relation: Historical development and present status – A brief review

The Sun and Earth are intimately related. A few decades ago, it was assumed that the relationship was only through the incidence of solar visible and infrared radiation on the surface of the Earth. However, it was soon realized that many powerful solar radiations reached the top of the terrestrial atmosphere but got absorbed in the upper part of the atmosphere, causing significant changes in the terrestrial environment. In this review, various processes are described, first on the Sun where various solar structures evolve, later in the interplanetary space due to escaping solar wind, and further in the interaction of the solar wind with the Earth’s magnetic field, containing it in the magnetosphere and entering through the neutral point in the magnetotail. Resulting phenomena like auroras, ring current, etc., are described. Present status of solar and interplanetary environments and their terrestrial effects is briefly outlined.     

Specific features of the high-speed plasma stream cycles

The high-speed plasma streams in the solar wind are investigated during the solar cycles nos. 20–22 (1964–1996), separately on the two types of streams according to their solar origin: the HSPS produced by coronal holes (co-rotating) and the flare-generated, in keeping with the classification made in different catalogues. The analysis is performed taking into account the following high-speed stream parameters: the durations (in days), the maximum velocities, the velocity gradients and, the importance of the streams. The time variation of these parameters and the high-speed plasma streams occurrence rate show an 11-year periodicity with some differences between the solar cycles considered. A detailed analysis of the high-speed stream 11-year cycles is made by comparison with the “standard” cycles of the sunspot relative number (Wolf number). The different behaviour of the high-speed stream parameters between even and odd solar cycles could be due to the 22-year solar magnetic cycle. The increased activity of the high-speed plasma streams on the descendant phases of the cycles, regardless of their solar sources, proves the existence of some special local conditions of the solar plasma and the magnetic field on a large scale that allow the ejection of the high energy plasma streams. This fact has led us to the analysis the stream parameters during the different phases of the solar cycles (minimum, ascendant, maximum and, descendant) as well as during the polar magnetic field reversal intervals. The differences between the phases considered are pointed out. The solar cycles 20 and 22 reveal very similar dynamics of the flare-generated and also co-rotating stream parameters during the maximum, descendant and reversal intervals. This fact could be due to their position in a Hale Cycle (the first component of the 22-year solar magnetic cycle). The 21st solar cycle dominance of all co-rotating stream parameters against the 20th and 22nd solar cycle ones, during almost all phases, could be due to the same structure of a Hale Cycle – solar cycle 21 is the second component in a 22-year SC. During the reversal intervals, all high-speed stream parameters have comparable values with the ones of the maximum phases of the cycles even if this interval contains a small part of the descendant branch (solar cycles 20 and 22).     

Forecasting the 23 and 24 solar cycles on the basis of MGM spectrum

A new method of nonlinear spectral analysis (called the method of global minimum: MGM), based on the best presentation (in sense of minimal squares) of a given time data set as a sum of sinusoids whose frequencies, amplitudes and phases are to be determined, has been used to find periodicities in annual Wolf sunspot numbers (W) during the period 1700–1995. The possible future behaviour of the 11-year solar cycle (based on an extrapolation of the calculated model) is also presented. The main characteristics of the 23^rd solar cycle are as follows: the W maximum occurs about 2004, with a peak of nearly 220. An unusually large value of W will occur during the 23^rd cycle, which should be characterised by the longest maximum, specifically, W will be greater than 100 during the 11-year period from 1997 to 2007. The first sharp rise will occur during the period 1996–1998, the second sharp during 2002–2004. The main features of the 24 year cycle are as follows: the next minimum in W, associated with the 24^th solar cycle, should occur in the year 2008 and the maximum in 2014. W is expected to peak at about 180. The minimum value for the 25^th year cycle is expected to occur in the year 2019. It is shown that the accuracy of these predictions depends, first of all, on the extrapolation of the hyperlong harmonic of the calculated polyharmonic model fit of observed annual sunspot numbers during the period 1700–1995. The error bars in the definition of the maximum and minimum epochs can be as large as two years.