The Ionospheric foF2 Data over Istanbul and their Response to Solar Activity for the Years 1964–1969 and 1993

A Polish-made vertical ionosonde (VI) has been operated at the Kandilli Observatory in Istanbul, for almost one year (May 1993 - April 1994) as part of the COST 238, PRIME Project, The critical frequencies were obtained for every half-hour interval. The data obtained during this campaign, on the descending branch of solar cycle 22, and the data measured earlier in Istanbul for cycle 20 were analysed and the characteristic behaviour of the F2 region ionosphere over Istanbul has been determined. This is a unique data set for this area. Several markers of the solar cycle activities in terms of the daily relative sunspot numbers, F10.7 cm solar radio flux and solar flare index, and the magnetic daily index of Ap were then used to seek the possible influence of the solar and ionospheric activities on the critical frequencies observed in Istanbul. It was found that the solar flare index, as a solar activity index, was more reliable in determining quiet ionospheric days. It is shown that the minimum and maximum time values of the solar activity are more convenient for ionospheric prediction and modelling.     

Solar Activity Indices for Ionospheric Parameters in the 23rd and 24th Cycles

Geomagnetism and Aeronomy - Characteristics of changes in the solar activity indices (the flux of the solar radio emission at a wavelength of 10.7 cm F and the new version of the relative sunspot...     

Estimation of the effect of solar activity on the intensity of galactic cosmic rays

The observations of solar activity (average monthly values of the international sunspot numbers and areas, solar radioemission flux at a wavelength of 10.7 cm) and galactic cosmic ray (GCR) intensity (average monthly values of the count rate of an omnidirectional Geiger counter at a maximum of the transition curve in the regions of Moscow and Murmansk and differences between these values) have been studied. The main aim of the studies was to assess the possibility of using the series of GCR values as an additional type of instrumental observations to predict solar activity. The results of an analysis made it possible to assess the degree of interrelation between the studied time series and, thereby, to confirm that GCRs, together with the characteristics of sunspot formation and solar radioemission flux at a wavelength of 10.7 cm, can be used to predict solar activity. The development of the current solar cycle has been predicted. It is assumed that the duration of this cycle will exceed the average value.     

磁暴活动与云南新一轮地震活跃期分析

对通海地磁台记录的磁暴(K指数≥5)年频次分析发现,磁暴活动的周期有强弱之分,与云南省地震活跃期和平静期对比分析看到,磁暴活动较强的周期时段与云南地震的活跃期相对应,磁暴活动较弱的周期时段与云南地震活动平静期相对应.目前,云南地震平静期已持续15年,即将进入第Ⅴ活跃期,大震发生的危险逐日增强.磁暴发生的数目和太阳活动有...     

Changed relation between sunspot numbers,solar UV/EUV radiation and TSI during the declining phase of solar cycle 23

We study the mutual relation of sunspot numbers and several proxies of solar UV/EUV radiation, such as the F10.7 radio flux, the HeI 1083 nm equivalent width and the solar MgII core-to-wing ratio. It has been noted earlier that the relation between these solar activity parameters changed in 2001/2002, during a large enhancement of solar activity in the early declining phase of solar cycle 23. This enhancement (the secondary peak after the Gnevyshev gap) forms the maximum of solar UV/EUV parameters during solar cycle 23. We note that the changed mutual relation between sunspot numbers and UV/EUV proxies continues systematically during the whole declining phase of solar cycle 23, with the UV/EUV proxies attaining relatively larger values for the same sunspot number than during the several decennia prior to this time. We have also verified this evolution using the indirect solar UV/EUV proxy given by a globally averaged f₀(F2) frequency of the ionospheric F2 layer. We also note of a simultaneous, systematic change in the relation between the sunspot numbers and the total solar irradiance, which follow an exceptionally steep relation leading to a new minimum. Our results suggest that the reduction of sunspot magnetic fields (probably photospheric fields in general), started quite abruptly in 2001/2002. While these changes do not similarly affect the chromospheric UV/EUV emissions, the TSI suffers an even more dramatic reduction, which cannot be understood in terms of the photospheric field reduction only. However, the changes in TSI are seen to be simultaneous to those in sunspots, so most likely being due to the same ultimate cause.     

Descriptive study of solar activity sudden increase and Halloween storms of 2003

During the declining phase of the last three solar cycles, secondary peaks have been detected 2–3 years after the main peak of sunspot number. The main peak of cycle 23 was in 2001, but a sudden increase of the solar activity occurred during the period October 17 to November 10, 2003 (the so-called Halloween storms). A similar storm occurred 1 year later, during the period October 3 to November 13, 2004. These events are considered as secondary peaks during the declining phase of cycle 23. Secondary peaks during declining phase of the last 10 solar cycles were detected by Gonzalez and Tsurutani [1990. Planetary and Space Science 38, 181–187]. During Halloween storm period, the sunspot area increased up to 1.11×10^?9 hemisphere on October 19, and grow up to 5.69×10^?9 hemisphere on October 30, 2003. Then it decreased to 1.11×10^?9 hemisphere on November 4, 2003. Also, the radio flux of λ=10.7 cm increased from 120 sfu on October 19, to 298 sfu on October 26, 2003, then decreased to 168 sfu on November 4, 2003. Two eruptive solar proton flares were released on 26 and 28 October 2003, the latter being the most eruptive flare recorded since 1976 (values reaching X17/4B).The aim of this study is to follow the morphological and magnetic changes of the active region before, during, and after the production of high-energy flares. Furthermore, the causes of release of these eruptive storms have been discussed for the period, October–November 2003, during the declining phase of the solar cycle 23.     

青海玉树地震的天文背景分析

系统地分析了青海玉树地震发生时的天体位置、太阳活动与地球自转等天文因素的影响.从大的长期天文背景来看,玉树地震发生于中国大震频发的月亮白赤交角由极大变到极小时期,并且是太阳活动的偶数周;从短临看,玉树地震正好发生在地球自转与太阳黑子数发生突跳的时期,且此时震中所受的天体引潮力加速度又处于其变化速率最大的极值附近.研究结果表明,这些天文因素对玉树地震的孕育与发生起到了不可忽视的作用,是值得进一步深入研究的.     

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.     

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。     

The 11-year solar cycle,the sun’s rotation,and the middle stratosphere in winter: Part I: Response of zonal means

The effect of the 11-year solar cycle on the response of the stratospheric geopotential height and temperature fields at 10 and 30 hPa in winter to solar activity oscillations with periods related to the period of the Sun’s rotation (27.2 days) is discussed, applying methods of statistical spectral analysis to daily data for the period from 1965 to 1996. Atmospheric responses for three periodicities — 27.2 days (period of the Sun’s rotation), 25.3 days (periodicity caused by the modulation of the 27.2 days oscillation by annual atmospheric variation), and 54.4 days (doubled period of the solar rotation) — are studied. A significant effect of the 11-year solar cycle on the atmospheric response to the 27.2 days solar periodicity has not been found. We explain it by a frequency shift of the response from the 27.2 days to the 25.3 days periodicity via amplitude modulation. For the 25.3 days oscillation, prominent differences between the maximum and minimum of the 11-year solar cycle have been found in the coherence between the 10.7 cm solar radio flux and the height/temperature fields: the relationships are stronger at solar maximum than at the minimum of the 11-year cycle. The same differences, but to a greater extent, are revealed for the oscillation with a period of 54.4 days. Coherence and amplitude estimates for this doubled solar rotation periodicity exhibit strong differences between extrema of the 11-year solar cycle. Phase estimates also demonstrate a clear difference between high and low solar activity: on the average, the delay of the atmospheric response after the solar signal is smaller at solar maximum than at solar minimum. Thus, we conclude that the mechanism of the influence of the 11-year solar cycle on the winter middle stratosphere can include both a direct effect of the frequency corresponding to the doubled solar rotation periodicity and an indirect effect of modulation of the intensity of the interaction between the solar 27.2 days oscillation and seasonal atmospheric variations.     

近40年菲律宾M_S≥7级地震时空结构及未来趋势再判断

整理了近40年菲律宾MS≥7级地震公开的灾害数据,采用可公度计算、蝴蝶结构图、可公度结构系等方法分析判断未来地震的时间;利用相邻地震震源经、纬度差变化分析震中的空间迁移;并利用震中经向、纬向迁移进行佐证,实现对其时空结构的未来趋势判断。通过判断发现菲律宾MS≥7级地震在2014年、2015年发生的信号较强;未来地震震中可能会在2013年10月15日菲律宾地震震中的东北方向,空间位置大致在9.8°N以北,126.704°E以东。菲律宾MS≥7级地震与地球自转速度变化有一定的关系,减速期发生地震的可能性更大,且速率转换的时间越长越易发生地震;同时发现太阳活动处于活跃强烈期内时,太阳黑子峰值、次峰值前后发生地震的概率很大。目前地球自转正处于减速期、太阳活动处于太阳黑子第24周期极大年附近,所以2014—2015年菲律宾发生MS≥7级地震的可能性很大。     

The 11-year solar cycle affects the intensity and annularity of the Arctic Oscillation

We investigate the dependence of the Arctic Oscillation (AO) in winter on the solar activity by stratifying the data into overlapping intervals defined by percentiles of the 10.7 cm radio flux. The AO exhibits a complex dependence of its polarity, being weakest under low, but not minimum, solar activity, while strongest in solar maxima. The AO is more/less variable (i.e., more/less active) under a high/low solar activity. Under a moderate solar activity, its Pacific centre weakens and eventually disappears. These effects seem to be real in spite of a potential for mixing the AO with the second principal component due to sampling errors caused by insufficient spacing between the first two eigenvalues. The weakening of the Pacific centre is not a result of coincidence with major volcanic eruptions or specific phases of the El Niño-Southern Oscillation.     

用模式识别方法研究强震发生的动力因子

用模式识别方法研究了大地震的发生时间与中等地震活动性、太阳活动水平、地球自转之间的关系.由模式识别所得的性质提出,大地震前中等地震活动达到一定水平是大地震可能发生的重要性质.而太阳活动极值前后及自转加速度变化较大时段可能触发大地震.      

Deep low-frequency earthquake swarm in the mid crust beneath Mount Fuji (Japan) in 2000 and 2001

Beneath Mount Fuji, the highest active volcano in Japan, deep low-frequency (DLF) earthquake activity has been monitored since the early 1980s. The DLF earthquakes occurred in the mid-crustal depth range, and burst-type activity lasting from several minutes to 30 min was detected 10 to 20 times in an ordinary year. The DLF earthquake activity increased sharply in the period from October 2000 to May 2001, showing swarm-like activity. The occurrence rate during the DLF earthquake swarm was approximately 20 times higher than the usual activity, and the wave energy released during the swarm period was twice as high as the total wave energy during the past 20 years. The DLF earthquakes in the period from 1987 to 2001 were relocated by estimating station corrections in order to reduce the effect of the change of seismic station distribution. The epicenters of most DLF earthquakes occurred in an elongated region with a long axis of about 5 km, whose center is located 2–3 km NE from the summit. A few percent of the DLF earthquakes, however, occurred around the summit area, significantly apart from the main epicenter region. The focal depths of well-located DLF events range from 10 to 20 km. During the high activity period in 2000 and 2001, most DLF events occurred within this main hypocenter area. The sharp increase of DLF earthquake activity at Mount Fuji started immediately after magma discharge and intrusion events in the Miyake-jima and Kozu-shima regions in July and August 2000. The tectonic and volcanic activity changes around the area suggest that the DLF earthquake swarm at Mount Fuji was triggered by the change of state of the deep magmatic system around Mount Fuji.Editorial responsibility: J Stix     

Solar-Activity Indices for the Ionosphere in Cycles 23 and 24: the Form of Cycles

Geomagnetism and Aeronomy - Analysis of the features of the form of low solar cycles 23 and 24 for the solar-activity indices (F is the solar radio flux at a wavelength of 10.7 cm, Rz and Ri are...     

Studying local sources in the radio range based on the partial solar eclipse of January 4, 2011, at the Mountain Astronomical Station, Central Astronomical Observatory, Russian Academy of Sciences

Data are presented on a partial solar eclipse, which occurred on January 4, 2011, and was observed with RT-3 (?? = 4.9 cm) and RT-2 (?? = 3.2 cm) radio telescopes at the Mountain Astronomical Station, Central Astronomical Observatory, Russian Academy of Sciences (MAS CAO RAS). The radioemission flux in two channels was registered using digital methods with a time resolution of 0.5 s. Comparisons were performed with observations in the optical, UV, and X-ray ranges. The following local sources of increased radioemission on the solar disk have been identified: sunspot groups 1 (NOAA 1142) and 126 (NOAA 1141), unipolar sunspot 127 (NOAA 1140), facula areas, and polar and midlatitude coronal holes. It has been indicated that the brightness of a unipolar sunspot (for ?? = 4.9 cm, I _rel = 29.5; for ?? = 3.2 cm, I _rel = 10.1) and two sunspot groups (for ?? = 4.9 cm, I _rel = 10.1 and 14.2; for ?? = 3.2 cm, I _rel = 5.1 and 6.2) is maximal. The radioemission flux of all found coronal holes is decreased, and the decrease is more contrasting in the 4.9-cm range as compared to such a decrease in the 3.2-cm range. Radio maps of the Sun and changes in the radioemission flux of undisturbed solar regions from the center to the limb for ?? = 4.9 and 3.2 cm have been constructed based on the eclipse data.     

太阳黑子活动及地球自转对江苏及邻区地震的影响分析

根据太阳黑子活动和地球自转数据,分析了两者对江苏及邻区中强地震的影响.结果显示:太阳黑子活动下降段及地球自转加速度上升和转折段有利于该地区中强地震的发生;且在太阳黑子活动的下降时间内,每一个地球自转加速度的转折都会使得该地区中小地震频度增高:另外,从幅相法统计以及太阳黑子活动预测数据来看,2012年2月以后江苏及邻区的...     

Total Solar Irradiance Observations

The record of total solar irradiance (TSI) during the past 35?years has overlapping observations from space which can be merged to a composite, and three are available, namely the PMOD, the ACRIM and the IRMB composites. There are important differences between them, which are discussed in detail in order to find the best representation of solar variability during the last three cycles, for the following discussions of solar irradiance variability. Moreover, the absolute value of TSI from TIM on SORCE is 1,361?Wm^?2, substantially lower than the value 1,365?Wm^?2, which was observed by the classical radiometers. New results from specific experiments are now available, which are discussed in order to define the value to be used in, e.g., climate models. The most important issue regarding the recent TSI records is the low value observed during the minimum in 2009, which is 25% of a typical cycle amplitude lower than the value in 1996. The validity of this low value has been confirmed by comparing all existing TSI observations during cycle 23. On the other hand, activity indices, such as the sunspot number, the 10.7-cm radio flux (F10.7), the CaII and MgII indices and also the Ly-α irradiance or the frequency changes in low-order p modes, show a much smaller decreases relative to their respective typical cycle amplitude. It is most likely that an increasing contrast of the facular and network elements with decreasing magnetic field is responsible for this discrepancy. The value of TSI at minima is correlated with the open magnetic field of the Sun, B _R,?at minima. Using B _R at minima, interpolated linearly in between as a fourth component of a proxy model based on the photometric sunspot index and on the MgII index improves the explanation of the variance of TSI over the full period of the last three solar cycles to 84.7%. Results from other models are also discussed.     

制约和影响中国大陆地震活动大形势的动力因素研究

从地球动力学角度,研究制约和影响我国大陆地震活动的兴衰起伏的内在原因,揭示我国大陆地震活动期（３００年）、幕（２０年左右）、段（几年）实际是由于太阳黑子活动、地球自转速率变化、全球强震活动水平在不同阶段迭加和组合的结果。     

Specific features of radio emissions of coronal holes based on eclipse and noneclipse observations at a solar activity minimum

Solar coronal holes (CHs) at a minimum of the 23rd activity cycle were investigated using Solar and Heliospheric Observatory (SOHO) data, ground-based observational data from the radio telescopes of the Kislovodsk Solar Station, Pulkovo Observatory (KSS PO), Russian Academy of Sciences, and radioheliograph data from the Nobeyama Observatory (Japan). The 2006–2008 period was characterized by a small number of active regions on the solar disk; nevertheless, this period is favorable for studying low-contrast objects in the radio band (CHs). We investigate the evolution of CH areas, the location of CHs on the solar disk, and the features of their radiation in the radio band. We present the results of observations of the total (March 29, 2006) and partial (August 1, 2008) solar eclipses by the RT-3 and RT-2 radio telescopes of the KSS PO. Based on the eclipse observation data, compact sources were identified on the solar disk and the contribution of CHs to the integral radio emission flux was estimated. A rare effect (increased radio emissions of high-latitude CHs at a wavelength of 4.9 cm) was revealed, which may be caused by X-ray bright points in CHs. Here, polar CHs are characterized by low levels of radio emission.