太阳总辐照的演化特征分析

太阳总辐照在23和24太阳活动周的显著周期分别为35 d和26 d,进而推断太阳的准旋转周期在23和24太阳活动周也分别为35 d和26 d.太阳总辐照在24周极小期的值可能与蒙德极小期的值相近.在一个太阳旋转周到几个月的时间尺度上,太阳黑子是引起太阳总辐照变化的主要原因,但不是唯一的原因;在几天到一个太阳旋转周的时间尺度上,太阳总辐照的变化与MgⅡ特征指数是不相关的.     

太阳黑子周极小年的统计性质——兼论第22周起始极小是否已经出现

探讨太阳周极小年的性质关系到确定极小值的位置及太阳周的长度,从而与太阳活动周的研究、太阳活动预报及水文、气象等地球物理现象的研究密切相关.当前对第22黑子周特征值的预报相当弥散,第22周起始极小是否已经出现的问题受到普遍关注.不同的太阳活动指标达到极值的时间不同,一般以太阳黑子数月均平滑最低值的位置来定义极小年.     

太阳活动周期的小波分析

运用小波技术对太阳射电流量2800 MHz,太阳黑子数和太阳黑子面积数周期进行分析．其结果表明: (1)这3个系列的数据显示最显著的周期是10．69年,其他周期并不明显．(2)小波功率谱给出了全部时间-周期范围的功率谱变化,它显示了在某个周期处于某个时段的局部功率的变化,小波功率谱分析表明,小于1年的周期仅仅在太阳活动最大期附近比较明显．(3)太阳射电2800 MHz,太阳黑子数和太阳黑子面积数的几个周期(10．69年,5．11年, 155．5天)的小波功率谱比较相似,出现峰值的时间相同;曲线的起伏相似,周期越小,曲线起伏的频率越大．     

我国地震和太阳活动的相关分析

一,我国和云南地区的地震活动,在地震频度方面大体存在着一个与太阳活动11年周期相关的周期,地震活动的峰值对应于太阳活动的降段。这种相关性在云南地区的地震活动中表现得尤为显著。 二、进一步分析云南地区各区域地质构造类型的地震活动性与太阳周期性活动的关系,分析表明:太阳活动周期与由于地球自转速率改变而形成的那类地质构造区域的地震相关性最显著。从而认为太阳周期性活动对地震的影响是通过地球自转速率改变的途径而进行的。 三,将太阳活动的周期性应用于云南地区地震的中长期趋势预报。     

太阳活动周的幅度与活动区面积关系的统计研究

依据太阳黑子的观测数据,首先分析了太阳活动周的幅度与太阳活动周内所有活动区面积总和的关系.分析结果表明,太阳活动周的幅度与太阳活动周内所有活动区面积总和具有很好的相关性.其次分析了太阳活动周的幅度与太阳活动周内最大活动区面积的关系.分析结果表明,太阳活动周的幅度与太阳活动周内最大活动区面积的相关性非常差,且一个太阳活动周最大活动区的出现时间与该太阳活动周的峰值时间并没有固定的时序关系.     

磁对流湍流对太阳P模振动的影响(英文)

为了进一步探索太阳对流区的物理性质 ,我们利用高精度N的日震观测数据来研究太阳内部扰动磁场对低阶太阳P模振动的影响。对于一个时间相关的MHD湍流源 ,我们给出了导致频率变化的各种可能性。如果只考虑磁扰动的贡献 ,不同值的振动模的频率变化仅只是涨落磁场能谱的函数。我们发现频率的变化随着太阳内部磁场强度增加而变大 ,并且和太阳活动周期密切相关。我们的计算表明太阳磁活动导致的频率变化可达 0 .3μΗz。     

太阳与地磁活动的1.3–1.7 yr振荡关系分析

太阳和地磁活动中的1.3–1.7 yr周期研究对于理解日地空间耦合系统中可能发生的物理过程十分重要.黑子是太阳光球层上最突出的磁场结构, Ap指数则是表征全球地磁活动水平的重要指标.使用同步压缩小波变换得到太阳黑子数和地磁Ap指数的1.3–1.7yr周期,并用互相关方法分析研究它们之间的相位关系.结果如下:(1)太阳黑子数和地磁Ap指数的1.3–1.7 yr周期呈现间歇性的演化特征,且随着时间的变化而不断变化;(2)地磁Ap指数在奇数活动周比相邻的偶数活动周的周期分量更高,表现出上下波动的变化特性;(3)地磁Ap指数和太阳黑子数的相位关系不是一成不变的,在大多数情况下地磁Ap指数滞后太阳黑子数,仅在第18和第22活动周黑子数在相位上滞后.     

太阳活动和预报的几个问题(英文)

不少人用统计方法研究太阳黑子数序列或者太阳黑子周本身各参量间的关系,做太阳活动周预报。第21周只有少数这类预报的结果与实际情况相近。第22周也会有类似的趋势,即预报较实测偏低较多。为改进预报,研究太阳黑子活动的性质是有益的。黑子数是一个缺乏物理意义的统计量,人们已经找到和正在寻找新的太阳活动指标。但是黑子数的观测历史较长,用户广,而且作为一个统计量它能反映太阳活动的时间变化,所以仍是一个常用的参量。同时,应该看到太阳活动是一个广泛含意的概念,不应把它只与黑子数相联系。为了满足用户的不同要求,应该用多种太阳活动指标做预报。另外,从SMM卫星和GOES卫星的观测资料分析得出耀斑的152天周期性,地面观测资料也得到了同样的结果。这类研究也必然有助于预报工作。本文对与上述问题有关的几点做些简短的讨论。 研究发现,太阳活动周各参量间的关系是比较复杂的。例如,太阳周黑子数极大值与上升段的关系似乎可以用两条直线表示(图1),极小年均值与起伏之间也象是双线关系(图2)。这种非唯一的关系至少是太阳活动周预报不准的主要原因之一,也可能是太阳预报提前期越长越不准的原因之一。 太阳活动是一个意义广泛的概念,可以用多种指标描述太阳活动的不同方面。而且应注意到不同指标之间在     

太阳活动与变化的150天周期研究进展

太阳活动，除了涵盖太阳表面磁场驱动的活动现象外，还包括光度、自转和对称性等物理因素的长期演化。研究它们变化的周期对深入理解其产生机制有着重要的指导意义。从1984年Rieger等人首次发现耀斑的产生率存在约154d周期始，人们在很多现象中都找到了它的踪影，150余d的周期成了继11yr太阳活动周和27d太阳自转周后最引人注目的新周期。重点综述了在耀斑、黑子等活动领域内对150d周期现象研究的现状，介绍了有关它成因的研究进展，指出了尚待解决的问题及进一步努力的方向。     

旋转黑子的太阳周时间延迟研究

统计结果显示23周旋转黑子的纬度随时间的变化呈蝴蝶图分布.对23周旋转黑子蝴蝶图和黑子蝴蝶图两翼的4条拟合曲线间的均方差随相位变化进行研究的结果表明:黑子蝴蝶图南北半球之间、旋转黑子蝴蝶图南北半球之间以及在同一半球旋转黑子蝴蝶图和黑子蝴蝶图之间存在着系统的时间延迟.这说明:23周南北半球太阳黑子活动不是同时发生的,南半球和北半球之间存在着系统的时间延迟或提前(相位差),且是南半球滞后于北半球;23周旋转黑子蝴蝶图和黑子蝴蝶图之间存在着相位差,且是旋转黑子蝴蝶图滞后于黑子蝴蝶图,观测滞后值略小于发电机模型预言的理论值.     

On the solar rotation and activity

The interaction between differential rotation and magnetic fields in the solar convection zone was recently modelled by Brun (2004). One consequence of that model is that the Maxwell stresses can oppose the Reynolds stresses, and thus contribute to the transport of the angular momentum towards the solar poles, leading to a reduced differential rotation. So, when magnetic fields are weaker, a more pronounced differential rotation can be expected, yielding a higher rotation velocity at low latitudes taken on the average. This hypothesis is consistent with the behaviour of the solar rotation during the Maunder minimum. In this work we search for similar signatures of the relationship between the solar activity and rotation determined tracing sunspot groups and coronal bright points. We use the extended Greenwich data set (1878–1981) and a series of full-disc solar images taken at 28.4 nm with the EIT instrument on the SOHO spacecraft (1998–2000). We investigate the dependence of the solar rotation on the solar activity (described by the relative sunspot number) and the interplanetary magnetic field (calculated from the interdiurnal variability index). Possible rotational signatures of two weak solar activity cycles at the beginning of the 20th century (Gleissberg minimum) are discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Wavelet Analysis of the Schwabe Cycle Properties in Solar Activity

Properties of the Schwabe cycles in solar activity are investigated by using wavelet transform. We study the main range of the Schwabe cycles of the solar activity recorded by relative sunspot numbers, and find that the main range of the Schwabe cycles is the periodic span from 8-year to 14-year. We make the comparison of 11-year‘s phase between relative sunspot numbers and sunspot group numbers. The results show that there is some difference between two phases for the interval from 1710 to 1810, while the two phases are almost the same for the interval from 1810 to 1990.     

Analysis of the 1.3–1.7 yr Oscillation Relationship between Solar and Geomagnetic Activities

The study on the 1.3–1.7 yr period of the solar and geomagnetic activities is very important for understanding the possible physical processes in the solar-terrestrial coupling system. The sunspot is the most prominent magnetic field structure in the solar photosphere, and the Ap index is an important indicator for the global geomagnetic activity level. The 1.3–1.7 yr period for the sunspot number and the geomagnetic Ap index is obtained by the synchro-squeezing wavelet transform, and the phase relationship between them is studied by the cross-correlation analysis. The main results are as follows: (1) The 1.3–1.7 yr period of the geomagnetic Ap index and sunspot number exhibits an intermittent evolutionary characteristics, and changes continuously with the time; (2) the geomagnetic Ap index has a higher periodic component in the odd solar cycles than the neighboring even solar cycles, which is characterized by fluctuations; (3) the phase relationship between the geomagnetic Ap index and the sunspot number is not always invariant, in most cases the geomagnetic Ap index lags behind the sunspot number, except in the 18th and 22th solar cycles.     

Solar cycle according to mean magnetic field data

To investigate the shape of the solar cycle, we have performed a wavelet analysis of the large–scale magnetic field data for 1960–2000 for several latitudinal belts and have isolated the following quasi-periodic components: ∼22, 7 and 2 yr. The main 22-yr oscillation dominates all latitudinal belts except the latitudes of ±30° from the equator. The butterfly diagram for the nominal 22-yr oscillation shows a standing dipole wave in the low-latitude domain  (∣θ∣≤ 30°)  and another wave in the sub-polar domain  (∣θ∣≥ 35°)  , which migrates slowly polewards. The phase shift between these waves is about π. The nominal 7-yr oscillation yields a butterfly diagram with two domains. In the low-latitude domain  (∣θ∣≤ 35°)  , the dipole wave propagates equatorwards and in the sub-polar region, polewards. The nominal 2-yr oscillation is much more chaotic than the other two modes; however the waves propagate polewards whenever they can be isolated.
We conclude that the shape of the solar cycle inferred from the large-scale magnetic field data differs significantly from that inferred from sunspot data. Obviously, the dynamo models for a solar cycle must be generalized to include large-scale magnetic field data. We believe that sunspot data give adequate information concerning the magnetic field configuration deep inside the convection zone (say, in overshoot later), while the large-scale magnetic field is strongly affected by meridional circulation in its upper layer. This interpretation suggests that the poloidal magnetic field is affected by the polewards meridional circulation, whose velocity is comparable with that of the dynamo wave in the overshoot layer. The 7- and 2-yr oscillations could be explained as a contribution of two sub-critical dynamo modes with the corresponding frequencies.     

Long-Term Variations in Solar Differential Rotation and Sunspot Activity

The solar equatorial rotation rate, determined from sunspot group data during the period 1879–2004, decreased over the last century, whereas the level of activity has increased considerably. The latitude gradient term of the solar rotation shows a significant modulation of about 79 year, which is consistent with what is expected for the existence of the Gleissberg cycle. Our analysis indicates that the level of activity will remain almost the same as the present cycle during the next few solar cycles (i.e., during the current double Hale cycle), while the length of the next double Hale cycle in sunspot activity is predicted to be longer than the current one. We find evidence for the existence of a weak linear relationship between the equatorial rotation rate and the length of sunspot cycle. Finally, we find that the length of the current cycle will be as short as that of cycle 22, indicating that the present Hale cycle may be a combination of two shorter cycles. Presently working for the Mt. Wilson Solar Archive Digitization Project at UCLA.     

The Effect of Solar Activity on the Annual Precipitation in the Beijing Area

Using continuous wavelet transform, we examine the relationship between solar activity and the annual precipitation in the Beijing area. The results indicate that the annual precipitation is closely related to the variation of sunspot numbers, and that solar activity probably plays an important role in influencing the precipitation on land.     

A Running Average Method for Predicting the Size and Length of a Solar Cycle

The running correlation coefficient between the solar cycle amplitudes and the max-max cycle lengths at a given cycle lag is found to vary roughly in a cyclical wave with the cycle number, based on the smoothed monthly mean Group sunspot numbers available since 1610. A running average method is proposed to predict the size and length of a solar cycle by the use of the varying trend of the coefficients. It is found that, when a condition (that the correlation becomes stronger) is satisfied, the mean prediction error (16.1) is much smaller than when the condition is not satisfied (38.7). This result can be explained by the fact that the prediction must fall on the regression line and increase the strength of the correlation. The method itself can also indicate whether the prediction is reasonable or not. To obtain a reasonable prediction, it is more important to search.for a running correlation coefficient whose varying trend satisfies the proposed condition, and the result does not depend so much on the size of the correlation coefficient. As an application, the peak sunspot number of cycle 24 is estimated as 140.4±15.7, and the peak as May 2012± 11 months.     

Solar activity forecast with a dynamo model

Although systematic measurements of the Sun's polar magnetic field exist only from mid-1970s, other proxies can be used to infer the polar field at earlier times. The observational data indicate a strong correlation between the polar field at a sunspot minimum and the strength of the next cycle, although the strength of the cycle is not correlated well with the polar field produced at its end. This suggests that the Babcock–Leighton mechanism of poloidal field generation from decaying sunspots involves randomness, whereas the other aspects of the dynamo process must be reasonably ordered and deterministic. Only if the magnetic diffusivity within the convection zone is assumed to be high (of order  10¹² cm² s⁻¹  ), we can explain the correlation between the polar field at a minimum and the next cycle. We give several independent arguments that the diffusivity must be of this order. In a dynamo model with diffusivity like this, the poloidal field generated at the mid-latitudes is advected toward the poles by the meridional circulation and simultaneously diffuses towards the tachocline, where the toroidal field for the next cycle is produced. To model actual solar cycles with a dynamo model having such high diffusivity, we have to feed the observational data of the poloidal field at the minimum into the theoretical model. We develop a method of doing this in a systematic way. Our model predicts that cycle 24 will be a very weak cycle. Hemispheric asymmetry of solar activity is also calculated with our model and compared with observational data.     

Historical Dataset Reconstruction and a Prediction Method of Solar 10.7 cm Radio Flux

We reconstruct the developing history of solar 10.7 cm radio flux (F10.7) since 1848, based on the yearly sunspot number and the variations. A relationship between the maximum and the linear regression slope of the first 3 years starting from minimum of the solar cycle is considered. We put forward a method of predicting the maximum of F10.7 by means of the slope-maximum relationship. Running tests for cycles 19 to 23 indicate that the method can properly predict the peak of F10.7.     

What do the solar activity indices represent?

Sunspot number, sunspot area, and radio flux at 10.7 cm are the indices which are most frequently used to describe the long‐term solar activity. The data of the daily solar full‐disk magnetograms measured at Mount Wilson Observatory from 19 January 1970 to 31 December 2012 are utilized together with the daily observations of the three indices to probe the relationship of the full‐disk magnetic activity respectively with the indices. Cross correlation analyses of the daily magnetic field measurements at Mount Wilson observatory are taken with the daily observations of the three indices, and the statistical significance of the difference of the obtained correlation coefficients is investigated. The following results are obtained: (1) The sunspot number should be preferred to represent/reflect the full‐disk magnetic activity of the Sun to which the weak magnetic fields (outside of sunspots) mainly contribute, the sunspot area should be recommended to represent the strong magnetic activity of the Sun (in sunspots), and the 10.7 cm radio flux should be preferred to represent the full‐disk magnetic activity of the Sun (both the weak and strong magnetic fields) to which the weak magnetic fields mainly contribute. (2) On the other hand, the most recommendable index that could be used to represent/reflect the weak magnetic activity is the 10.7 cm radio flux, the most recommendable index that could be used to represent the strong magnetic activity is the sunspot area, and the most recommendable index that could be used to represent the full‐disk magnetic activity of the Sun is the 10.7cm radio flux. Additionally, the cycle characteristics of the magnetic field strengths on the solar disk are given. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)