There is a close correlation between sunspot number and sunspot area. Through the distribution of sunspot number and area size, we could note significantly disagreements for the two hemispheres. The paper concentrates on the relationship for the northern, the southern hemispheres and the global, and we propose a new method from segmentation regression for description the relationship between the sunspot number and sunspot area of different hemispheres and the global. By the sunspot number, we divide up the data into three parts, the low, the medium, and the high. The results indicate that the segmentation regression method could better describe the relation between sunspot area and number, in particular at the lower solar activity part and the higher part. We could obtain a better regression result for these parts, data more or less static, and data more discrete. Moreover, sunspot area and number behave very differently relationship for the north, the south and the global. In addition, the sunspot number being equal, the sunspot area of the south is usually greater than the north.

This paper focuses on the temporal evolution and shape of northern and southern hemispheric sunspot number. The comparisons, whether from time-varying spectral analysis or global power spectrum before and after filtering, imply the similarity and difference in the characteristics of periods between the northern and southern hemispheres. We have decomposed monthly hemispheric standardized sunspot of cycles 19–24 using principal component (PC) analysis and reconstructed based on the three principal components. These exhibit different characteristics of variation. And the main determinant of variation in various cycles is the second and third PC, whatever the hemisphere is. The comparisons we have outlined imply the hemispheric asymmetry. The difference analysis of the temporal evolution, shape of hemispheric sunspot cycles, and asymmetry is of great importance in understanding the global cycle variation and its evolution to fully understand the physical mechanism of the solar periodic variation and hemispheric asymmetry.

Proton cyclotron waves (PCWs) upstream from Mars are usually interpreted as waves generated by ion/ion instabilities due to the interaction between the solar wind plasma and the pickup protons, originating from the extended hydrogen (H) exosphere of Mars. Their generation mainly depends on the solar wind properties and the relative density of the newborn protons with respect to the background solar wind. Under stable solar wind conditions, a higher solar irradiance leads to both increased exospheric H density and ionization rate of H atoms, and therefore a higher relative density, which tends to increase the linear wave growth rate. Here we show that the solar irradiance is likely to contribute significantly to PCW generation. Specifically, we present observations from the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft indicating that, around the peak of the X8.2 flare on 2017 September 10, the increased solar irradiance gave rise to higher pickup H + fluxes, which in turn excited PCWs. This result has implications for inferring the loss of hydrogen to space in early Martian history with more intense and frequent X-class flares as well as their contributions to the total loss.

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.

建筑冻害是冰雪灾害的衍生灾害之一,为了降低其对建筑带来的损害,以中原阁楼建筑为例,对冰雪灾害给建筑空间环境产生的冻害机理进行分析.以中原阁楼建筑结构为基础,搭建建筑空间环境模型.在该模型下模拟演化冰雪灾害的冻害过程,并分析建筑冻害的具体表现.在温度和湿度影响下,分析中原阁楼建筑空间环境的冻胀力变化和力学性质变化,得出阁楼建筑冻害机理的分析结果,并通过将分析结果应用到实际建筑修复工作当中,通过修复率,验证冰雪灾害后中原阁楼建筑空间环境冻害情况.

太阳黑子是太阳活动的重要外在特征,且与诸多太阳活动指标有良好的相关性.黑子数据在太阳活动、空间环境、日地关系及地球气候变化等方面均有广泛应用.国际太阳黑子相对数是各类黑子数据中观测时间最长的时间序列,在诸多研究中均有十分重要的作用.2015年,国际太阳黑子相对数经过校订,公布了新版本.新、旧版本的数据存在诸多差别,而这些差别可能会对使用该数据开展的研究以及研究方法造成一定的影响.本文对新、旧版本数据进行对比,简述了二者间的差别,并说明原因,且以已有研究为例,具体讨论了数据更替对研究工作的影响.

In addition to the evident 11-year periodic changes, Total solar irradiance (TSI) also has some short-period processes. We carried out the wavelet analysis for TSI observational series and its inter-annual time series that is filtered out components less than 2 years and more than 8 years . Whether the wavelet graph or the global wavelet power spectrum, the results significantly show that there is a short period about 5.3 years, and its length and intensity both vary with time. Specifically, the strength of this period varies with the 11-year cycle change, showing pronounced characteristics of peak strength and valley weakness. Moreover, the amplitude of these low-frequency fraction results indicates different TSI variation properties. Under each solar cycle, the sum of the power spectrum density of the 3–6 year period terms reflects that the energy value of the short period is concentrated in that range. When the 11-year cycle is intensive, the 3–6 year period also becomes intensive in TSI. And the total spectral intensity of TSI will be concentrated in that short-period terms.

本文介绍了一种针对多元数据的中心对称性检验和中心估计问题所提出的新方法.方法中的检验统计量是基于经验特征函数并使用了两个特殊的权重函数的权重积分,具有简单和封闭的形式,并易于计算.基于这一新的检验统计量,进一步又能导出相应的具有渐近正态性的最小距离估计量作为中心估计量.与传统的中心估计量相比,新的估计量在稳健性方面有较大的优势.我们将这一新的基于经验特征函数加权积分的中心估计法用于研究太阳黑子相对数、黑子面积和太阳总辐射流量这三个太阳活动的主要参数,以期寻找大量观测时点中更能代表太阳活动变化特征的时期数据序列.通过与均值法和中位数法的比较,新方法一方面能够在太阳活动变化剧烈的时期体现出其在稳健性方面的优势,另一方面又能够在其他时期基本保持和均值法相近的有效性.新的数据序列与东北地区雪盖面积变化的相干分析表明,在多个不同频段二者均存在着相干关系,说明太阳活动对雪盖变化存在影响.

Sunspot-number prediction plays a very important role in space-weather forecasts and environmental research. In 2015, the international relative sunspot-number publisher released a new version of the data. Compared with the old version, the new data changed enough to influence sunspot-prediction methods that were based on the old data. The aim of this study is to propose a new prediction method based on the new data, and improve prediction accuracy as much as possible. A modified gaussian function, which has four parameters, was used in our method to describe each single cycle. Via four relationships among the four parameters, we found the most probable values and their uncertainties for the four parameters, and then we obtained the sunspot-number variation curve and its range for Solar Cycle 24. The results showed that the peak value should be 113.3 (the real value was 116.4), at the 57th month (between the two real peak at the 39th and the 64th month). A range of peak values was also given by this method, which range from 91 (less than the real value by 25) to 134 (greater than the real value by 18).

The critical value of correlation coefficient vertical bar r vertical bar(C), which varies with the degree of windowed moving average k, freedom n and confidence xi, is widely accepted to judge the linear relationship between two independent samples X and Y. In order to avoid referring to inconvenient critical value tables or using time-consuming Monte Carlo (MC) simulation, this paper presents a mathematically unified model for calculating the critical value. In this paper, both independent samples X and Y follow the standard normal distribution. We analyse MC result vertical bar r vertical bar(MC) for these samples X, Y to establish the model parameters and then examine the model result vertical bar r vertical bar(MO) for three different astronomical fields to calculate the confidence level xi of sample correlation coefficient vertical bar r vertical bar, which is compared with MC result vertical bar r vertical bar(MC). The results show that the MC results vertical bar r vertical bar(MC) and model results vertical bar r vertical bar(MO) are in exceptionally good agreement, and the applicability of the model to obtain the confidence level xi is satisfactory when calculating the sample correlation coefficient vertical bar r vertical bar for two independent samples X and Y.

The variations in the Earth’s rotation are important to space dynamic theory and natural disasters because they affect the length-of-day (LOD) and consequently human lives. We use maximum entropy method (MEM), Lomb method (LOMB), and phase dispersion minimization (PDM) to determine the natural periods of equally spaced LOD time series. We transform the observational monthly LOD time series (LODM) to unequally sampled series (LODMD) by removing every fourth, third, and half of the total samples. We also apply spline interpolation to LODMD to yield equally spaced time series (LODMDN). The results suggest that regardless of the time series, the MEM frequency is 0.1660 month–1 and 0.0840 month–1, whereas LOMB and PDM yield 0.166 month–1 and 0.083 month–1, respectively. Furthermore, missing data that are less than half of the total data or spline interpolation do not affect the analysis. For the amplitude, neither missing data nor spline interpolation affect the analysis.

We introduce two methods to detect short-period variation in solar activity. These are called amplitude of low frequency fluctuation (ALFF) and fractional amplitude of low frequency fluctuation (FALFF). We find a positive correlation between short-period variation and 11-year variation of solar activity using these two methods. Through ALFF, we find that solar activity over a short period becomes intensive when the 11-year solar activity is intensive. The ALFF value of the short period activity varies with the peak in sunspot number as a quadratic function. Through FALFF we find that the ratio of short-period spectral intensity to intensity over the whole period of solar activity will increase when the 11-year period of solar activity is intensive. The short-period FALFF value varies with the peak in sunspot number according to a cubic function. Using ALFF, we obtain a yearly series of solar activity that varies over a short period of 1–5 yr from 1860 to 2003, which shows an obvious periodicity of about 22 yr, 33 yr, 11 yr and a century. These short period variations show good correlations with long term variations in solar activity.

Whether natural factors could interpret the rise of the Earth's surface temperature is still controversial. Though numerous recent researches have reported apparent correlations between solar activity and the Earth's climate, solar activity has encountered a big problem when describing the rapid global warming after 1970s. Our investigation shows the good positive correlations between the Earth's surface Ultraviolet irradiance (280-400 nm) and the Earth's surface temperature both in temporal and spatial variations by analyzing the global surface Ultraviolet irradiance (280-400 nm) and global surface temperature data from 1980-1999. The rise of CO$_2$ cannot interpret the good positive correlations, and we could even get an opposite result to the good correlations when employing the rise of CO$_2$ to describe the relation between them. Based on the good positive correlations, we suggest a new effect, named "Highly Excited Water Vapor" (HEWV) effect, which can interpret how the Sun influences the Earth's surface temperature reasonably, including the rapid warming after 1970s.

It is suggested by Chen {\it et al.} that the Earth's surface Ultraviolet irradiance ($280-400$ nm) could influence the Earth's surface temperature variation by "Highly Excited Water Vapor" (HEWV) effect. In this manuscript, we reconstruct the developing history of the ozone layer depth variation from 1860 to 2011 based on the HEWV effect. It is shown that the reconstructed ozone layer depth variation correlates with the observational variation from 1958 to 2005 very well ($R=0.8422$, $P>99.9\%$). From this reconstruction, we may limit the spectra band of the surface Ultraviolet irradiance referred in HEWV effect to Ultraviolet B ($280-320$ nm).

The computational astronomy course is surveyed in detail at astronomy or astrophysics department of some famous universities.From comparing the teaching program,course arrangement and course content of the computational astronomy course of different universities,we should broad the reform thoughts in teaching program.

Astronomy is a discipline based on observations.Trairring of talents in astronomy and public education in astronomy pose various requests to astronmrucal practice teaching.For recent years,Department of Astronomy of Beijing Normal Universily has built multi-level of practice platform for astronomical teaching,providing targeted practice teaching conditions for professional and non-professional,undergraduate and graduate students.New explorations and attempts have been carried out in practice aspects of training of high-quality astronomical talents and teaching of high-quality astronomical public courses.A number of innovative achievements in education and teaching have been obtained which are worth of application and popularization.

Based on the time series of station coordinates provided by international SLR service (ILRS) over 1993–2011 using a set of global 92 ILRSA fiducial stations and by international VLBI service (IVS) over 1980–2009 using a set of global 113 VLBI fiducial stations, we generated a time series of the geocenter motion (GCM) and scale factor variations in terms of the network shift approach, which has been the longest and highest accurate one until now. Fourier analysis and wavelet analysis were employed to analyze the nonlinear variations of GCM and scale factor time series. The results indicate that the variations of GCM and scale are dominated by annual and semiannual motions, and show certain long periodic variations. The amplitude and phase of the annual and semiannual motions has certain changes in different years.

In order to uncover a possible influence on the Earth’s climate, we need a much longer time series, i.e., the total solar irradiance (TSI) which is also an interesting issue in its own right in solar physics. By comparing different solar indices associated with TSI during the period 1979 to 2009, several empirical models in the TSI are presented. We verify that the reconstruction model based on the three variables: sunspot number, sunspot area, and solar 10.7 cm radio flux, is the best one. As demonstrated by model calculations, the history of TSI was reconstructed back to 1947 based on 3-indices and to 1874 based on 2-indices, respectively. The reason that the reduced irradiance on the trough during 2006 to 2009 lasts long may be due to the about 85-year cycle of solar activity, which modulates the intensity of the 11-year cycle (Schwabe cycles), possesses a considerable potential to produce an effective reducing, and holds on a steadily lower level of irradiance.

Maximum entropy method(MEM) is a common way of spectrum analysis in astronomy research.ΔLOD,which reflects earth rotation variation,was analyzed with MEM.One half(1/2),1/3 and 1/4 of total sample of observed series were deduced randomly and they were made equally spaced time series by spline interpolation.These series were analyzed again using MEM,the influence of interpolation on spectrum analysis was investigated.Data demonstrated that interpolation may change the outcome of spectrum analysis and generate some false period components.The accuracy of period was related to the amount of interpolation data.

We analyzed the relationship between the earth’s rotational variation and sea-surface temperature anomaly. By means of using Fast Fourier Transform (FFT) bandpass filter on the change of length-of-day (ΔLOD) data, the interannual variation series having time periods greater than 1.5-year and less than 8-year was obtained. Time series analyses of the interannual variation, which corresponds to the El Niño period, reveal a close linkage between the earth’s rotation and El Niño. A detailed comparison suggests, that six of seven El Niño events are nearly synchronous with the interannual variation of the earth’s rotation, and all ΔLOD peak are in El Niño years except 1991–92, which means the interannual variation of the earth’s rotation in these years is relatively slow. The correlation between ΔLOD and sea-surface temperature is about 0.517 (1 month-lag), which far exceeds the 99% significance level.