共查询到20条相似文献，搜索用时 109 毫秒
1.
A long series of the known Π index of the solar corona structure has been proposed. It seems that this index, which characterizes the limb extension of polar coronal plume systems, is of importance because it is related to the large-scale polar solar magnetic flux. Solar corona photographs and drawings during total solar eclipses, collected for 13 solar activity cycles from different sources (78 eclipses), as well as H-alpha map data on the drift of the high-latitude belt of filaments before polarity reversal of the polar magnetic field have been used. Daily solar corona images, obtained on the SOHO spacecraft (using an EIT ultraviolet telescope), have been additionally used. 相似文献
2.
日冕物质抛射(CME)的规模和对地有效性是地磁暴预报中重点关注的特征.本项研究的目的是通过对行星际高能质子通量和能谱的特征与演化规律的分析,得到CME对粒子的加速能力,评估CME可能对地磁场造成的影响.在工作中,统计分析了ACE/EPAM的1998-2010年的质子数据,对质子能谱进行了拟合,得到了能谱指数,并对能谱指数及其变化特征所对应的CME和地磁暴进行了相关统计.通过研究发现:(1)能谱指数随着太阳活动水平而变化,高年最大,达到-2.6,而且涨落幅度也达到±0.4,而在太阳活动低年则稳定在-3.0左右;(2)CME对粒子的加速对应着能谱指数的升高,幅度达到20%时,CME引起地磁暴的可能性较大;(3)冕洞高速流到达地球时,高能质子通量也会升高,但能谱指数同时会有下降;(4)以2004年全年的能谱指数为例,对能谱指数在地磁暴预报中的应用进行了评估,结论认为,能谱指数的升高是CME引发地磁暴的必要条件,可以作为地磁暴预报的参数使用. 相似文献
3.
Applying spectral analysis to the Atlantic and Pacific hurricane time series, we found periodicities that coincide with the main sunspot and magnetic solar cycles. To assess the possibility that these periodicities could be associated with solar activity, we obtain correlations between hurricane occurrence and several solar activity-related phenomena, such as the total solar irradiance, the cosmic ray flux and the Dst index of geomagnetic activity. Our results indicate that the highest significant correlations are found between the Atlantic and Pacific hurricanes and the Dst index. Most importantly, both oceans present the highest hurricane–Dst correlations during the ascending part of odd solar cycles and the descending phase of even solar cycles. This shows not only the existence of a 22 yr cycle but also the nature of such periodicity. Furthermore, we found that the Atlantic hurricanes behave differently from the Pacific hurricanes in relation to the solar activity-related disturbances considered. 相似文献
4.
Gui-Qing Zhang 《地震学报(英文版)》1998,11(4):495-500
The relations between sunspot numbers and earthquakes (M≧6), solar 10.7 cm radio flux and earthquakes, solar proton events and earthquakes have been analyzed in this paper. It has
been found that: (1) Earthquakes occur frequently around the minimum years of solar activity. Generally, the earthquake activities
are relatively less during the peak value years of solar activity, some say, around the period when magnetic polarity in the
solar polar regions is reversed. (2) the earthquake frequency in the minimum period of solar activity is closely related to
the maximum annual means of sunspot numbers, the maximum annual means of solar 10.7 cm radio flux and solar proton events
of a whole solar cycle, and the relation between earthquake and solar proton events is closer than others. (3) As judged by
above interrelationship, the period from 1995 to 1997 will be the years while earthquake activities are frequent. In the paper,
the simple physical discussion has been carried out.
These results supported the exploration and studies of some researchers to a certain extent.
This work is supported by Foundation of the Chinese Academy of Sciences (major item). 相似文献
5.
2001年4月2日, 太阳爆发了一个近年来X射线通量最大的一次耀斑并伴有质子事件, 利用“资源一号”卫星星内粒子探测器和神舟二号飞船X射线探测器的观测资料, 对这一事件的高能粒子响应进行了特例研究. “资源一号”卫星运行于太阳同步轨道, 高度约800km, 和宁静时期的统计结果对比, 这次耀斑后, 星内粒子探测器在地球极盖区（地球开磁场区）观测到耀斑粒子的出现, 这是宁静时期没有的; 神舟二号飞船轨道高度400km, 倾角为42°, X射线探测器在42°中高纬地区也观测到高能电子通量比宁静时明显的增加, 这表明, 太阳耀斑引起的近地空间辐射环境的变化遍及纬度约40°以上的区域, 甚至在40°N附近400 km左右的高度上仍然有响应. 但是, 中高纬度、极光带和极盖区的粒子来源, 加速机制和响应方式却不一定相同, 需要分别讨论. 资料分析和对比还表明, 质子事件的强度并不一定和耀斑的X射线通量成正比, 因此, 近地空间高能粒子对耀斑的响应也不是完全决定于X射线强度. 相似文献
6.
A previous application of extreme-value statistics to the first, second and third largest geomagnetic storms per solar cycle for nine solar cycles is extended to fourteen solar cycles (1844–1993). The intensity of a geomagnetic storm is measured by the magnitude of the daily aa index, rather than the half-daily aa index used previously. Values of the conventional aa index (1868– 1993), supplemented by the Helsinki Ak index (1844–1880), provide an almost continuous, and largely homogeneous, daily measure of geomagnetic activity over an interval of 150 years. As in the earlier investigation, analytic expressions giving the probabilities of the three greatest storms (extreme values) per solar cycle, as continuous functions of storm magnitude (ad), are obtained by least-squares fitting of the observations to the appropriate theoretical extreme-value probability functions. These expressions are used to obtain the statistical characteristics of the extreme values; namely, the mode, median, mean, standard deviation and relative dispersion. Since the Ak index may not provide an entirely homogeneous extension of the aa index, the statistical analysis is performed separately for twelve solar cycles (1868–1993), as well as nine solar cycles (1868–1967). The results are utilized to determine the expected ranges of the extreme values as a function of the number of solar cycles. For fourteen solar cycles, the expected ranges of the daily aa index for the first, second and third largest geomagnetic storms per solar cycle decrease monotonically in magnitude, contrary to the situation for the half-daily aa index over nine solar cycles. The observed range of the first extreme daily aa index for fourteen solar cycles is 159–352 nT and for twelve solar cycles is 215–352 nT. In a group of 100 solar cycles the expected ranges are expanded to 137–539 and 177–511 nT, which represent increases of 108% and 144% in the respective ranges. Thus there is at least a 99% probability that the daily aa index willAlso Visiting Reader in Physics, University of Sussex, Palmer, Brighton, BN1 9QH, UK 相似文献
7.
In situ measurements of the solar wind largely cover more than two solar magnetic activity cycles, namely 20 and 21. This is a very appealing opportunity to study the influence of the activity cycle on the behaviour of the solar wind parameters. As a matter of fact, many authors so far have studied this topic comparing the long-term magnetic field and plasma averages. However, when the average values are evaluated on a data sample whose duration is comparable with (or even longer than) the solar rotation period we lose information about the contribution due to the fast and the slow solar wind components. Thus, discriminating in velocity plays a key role in understanding solar cycle effects on the solar wind. Based on these considerations, we performed a separate analysis for fast and slow wind, respectively. In particular, we found that: (a) fast wind carries a slightly larger momentum flux density at 1 AU, probably due to dynamic stream-stream interaction; (b) proton number density in slow wind is more cycle dependent than in fast wind and decreases remarkably across solar maximum; (c) fast wind generally carries a magnetic field intensity stronger than that carried by the slow wind; (d) we found no evidence for a positive correlation between velocity and field intensity as predicted by some theories of solar wind acceleration; (e) our results would support an approximately constant divergence of field lines associated with corotating high-velocity streams. 相似文献
8.
It is proposed to determined minimums of the 11-year solar cycles based on a minimal flux of the large-scale open solar magnetic field. The minimal fluxes before the finished cycle 23 (Carrington rotation CR 1904) and the started cycle 24 (CR 2054, April 2007) were equal to 1.8 × 1022 and 1.2 × 1022 μs, respectively. The long-term tendency toward an approach to a deep minimum of solar activity is confirmed. On the assumption that magnetic flux variations from minimums to maximums are proportional to each other, the anticipated value of the maximal Wolf number during cycle 24 is estimated as W max = 80. 相似文献
9.
R. T. Gushchina A. V. Belov V. N. Obridko B. D. Shelting 《Geomagnetism and Aeronomy》2010,50(4):436-442
Based on observations of long-term variations in galactic cosmic rays (CRs) on Earth and in the near-Earth space, we have
determined, using our own semiempirical model, modulation of galactic CRs during solar cycles 19–23. The modulation model
relates CR variations to the characteristics of the solar magnetic field obtained for the surface of the solar wind source
at distances of 2.50 and 3.25 solar radii. The main focus is CR behavior at the minimums of cycles 19–23 and specific features
of CR modulation at a prolonged (as compared to previous cycles) minimum of cycle 23, which is still ongoing. CR modulation
at minimums related to a change in the solar field dipole component during this period of the cycle has been considered. It
is indicated that the long-term variations in CRs are better described if the last two years (2007 and 2008) of cycle 23 with
anomalously low solar activity (SA) are included in the model. The role and value of the contribution of the cyclic variations
in each index used in the proposed CR modulation model to the observed CR modulation have been estimated. 相似文献
10.
Hiroko Miyahara Yusuke Yokoyama Kimiaki Masuda 《Earth and Planetary Science Letters》2008,272(1-2):290-295
The linkage between multi-decadal climate variability and activity of the sun has been long debated based upon observational evidence from a large number of instrumental and proxy records. It is difficult to evaluate the exact role of each of solar parameters on climate change since instrumentally measured solar related parameters such as Total Solar irradiance (TSI), Ultra Violet (UV), solar wind and Galactic Cosmic Rays (GCRs) fluxes are more or less synchronized and only extend back for several decades. Here we report tree-ring carbon-14 based record of 11-year/22-year solar cycles during the Maunder Minimum (17th century) and the early Medieval Maximum Period (9–10th century) to reconstruct the state of the sun and the flux of incoming GCRs. The result strongly indicates that the influence of solar cycles on climate is persistent beyond the period after instrumental observations were initiated. We find that the actual lengths of solar cycles vary depending on the status of long-term solar activity, and that periodicity of the surface air temperatures are also changing synchronously. Temperature variations over the 22-year cycles seem, in general, to be more significant than those associated with the 11-year cycles and in particular around the grand solar minima such as the Maunder Minimum (1645–1715 AD). The polarity dependence of cooling events found in this study suggests that the GCRs can not be excluded from the possible drivers of decadal to multi-decadal climate change. 相似文献
11.
In this paper, we consider variations in energetic electron fluxes at a geostationary orbit, which are related to the Sun’s
rotation period, during two solar cycles. We use data on energetic electron fluxes obtained from the GOES (1986–2007) (>2
MeV) and LANL (1996–2007) (50–225 and 315–1500 keV) satellites. Within the solar cycle, we observed both periods of high flux
peak recurrence during several rotations and periods when there was no (or a low) 27-day recurrence. We show the similarity
and difference between manifestations of flux recurrences from cycle to cycle. Insignificant manifestation of recurrence and
its absence were observed mainly during the solar maximum. High electron flux recurrence was observed mainly at the phase
of decline in solar activity (near the solar minimum). We show that for both solar cycles, there were several days (within
the Bartels rotation) during which increased energetic electron fluxes would be most likely observed. 相似文献
12.
A.A. Hady 《Journal of Atmospheric and Solar》2009,71(17-18):1711-1716
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. 相似文献
13.
D. M. Volobuev 《Geomagnetism and Aeronomy》2013,53(7):887-890
It is known that the solar component is difficult to find in a climatic signal due to its small size and significant internal random disturbances of the climatic system, such as variations in cloudiness, precipitation, winds, and oceanic currents. In the center of the polar cap, these disturbances are as minimal as possible; therefore, solving the inverse heat conduction problem, we can calculate the informative heat flux through the ice cover based on temperature data. Variations in the heat flux are quite significant in amplitude (0.2–0.3 W/m2) and coincide with the 11-year solar cycle in phase. Application of this approach to the indices of the global and sea surface temperatures cannot yield a solar signal, yet it can be traced for solar cycles with big amplitude (cycles 19 and 21). Thus, the found variation in the heat flux is most probably caused by a change in the solar constant (TSI); however, other mechanisms are also possible. 相似文献
14.
A. A. Melkumyan A. V. Belov M. A. Abunina A. A. Abunin E. A. Eroshenko V. A. Oleneva V. G. Yanke 《Geomagnetism and Aeronomy》2018,58(5):615-624
The IZMIRAN database of Forbush effects and interplanetary disturbances has been used to study long-term changes in the number and magnitude of Forbush effects in the last six solar cycles (1957–2016) for cosmic rays of rigidity of 10 GV. Solar activity cycles have been shown to be well expressed in data of Forbush effects, especially in large magnitude events that almost disappear in minima. The changes in the distribution of Forbush effects and the decrease in their average values from solar activity maximum to minimum are explained by the predominance of cosmic-ray variations due to the action of coronal holes at low activity. It should be noted that the current cycle involves fewer and generally weaker Forbush effects than in the previous five cycles. For each month, an FD index combining the magnitude and number of Forbush effects and convenient for studying long-term variations has been proposed and calculated. 相似文献
15.
A. A. Krivolutsky A. A. Kuminov A. A. Kukoleva A. I. Repnev N. K. Pereyaslova M. N. Nazarova 《Geomagnetism and Aeronomy》2008,48(4):432-445
Using the data on solar proton fluxes measured on board the GOES satellites, the most powerful solar proton events (SPEs) of solar cycle 23 are selected, and ionization rates in the atmosphere in these periods at high latitudes of the Northern Hemisphere are calculated. Assuming that each ion pair formed at the retardation of solar protons in the atmosphere leads to the formation of 1.25 molecules of nitric oxide, 2.0 molecules of the OH radical, and one oxygen atom, changes in the content of ozone, nitrogen and other compounds were calculated using a photochemical model. The calculations showed that the strongest ionization and destruction of ozone was caused by SPEs that occurred on July 14, 2000; November 8, 2000; November 4, 2001; and October 28, 2003. The results can form the basis for compiling the catalog of changes in ionization and ozone in the atmosphere caused by solar proton activity. 相似文献
16.
We investigate here the fluctuations in the total, open and closed solar magnetic flux (SMF) for the period 1971–1999 by means of the maximum entropy method in the frequency range 5×10−9–10−7 Hz (6 yr to 120 days). We use monthly data for the total, open and closed magnetic solar fluxes. Periodicities found in the series are similar showing that there is some relationship between the fluxes. The most important finding of this work is the existence of fluctuations at around 1.3 and 1.7 yr in the SMF with alternating importance during consecutive even and odd solar cycles. These fluctuations are directly related with variations present in cosmic rays, solar wind parameters and geomagnetic activity indexes. A quasi-triennial periodicity previously found in sunspots and other solar phenomena is also of importance. The SMF is generated by the action of the solar dynamo; therefore, it is through the magnetic flux that the solar dynamo influences several heliospheric phenomena. 相似文献
17.
A. Prestes N. R. Rigozo D. J. R. Nordemann E. Echer L. E. A. Vieira M. P. Souza Echer C. M. Wrasse F. L. Guarnieri 《Pure and Applied Geophysics》2014,171(8):1983-1991
Evidence of the solar activity modulation of the Earth’s climate has been observed on several parameters, from decadal to millennial time scales. Several proxies have been used to reconstruct the paleoclimate as well as the solar activity. The paleoclimate reconstructions are based on direct and/or indirect effects of global and regional climate conditions. The solar activity reconstructions are based on the production of the 14C isotope due to the interaction of cosmic ray flux and the Earth’s atmosphere. Because trees respond to climate conditions and store 14C, they have been used as proxies for both for climate and solar activity reconstructions. The imprints of solar activity cycles dating back to 10,000 years ago have been observed on tree-ring samples using 14C data, and those dating back to 20 million years ago have been analyzed using fossil tree-growth rings. All this corresponds to the Cenozoic era. However, solar activity imprints on tree rings from earlier than that era have not been investigated yet. In this work, we showed that tree rings from the Mesozoic Era (of ~200 million years ago) recorded 11- and 22-year cycles, which may be related to solar activity cycles, and that were statistically significant at the 95 % confidence level. The fossil wood was collected in the southern region of Brazil. Our analysis of the fossils' tree-ring width series power spectra showed characteristics similar to the modern araucaria tree, with a noticeable decadal periodicity. Assuming that the Earth’s climate responds to solar variability and that responses did not vary significantly over the last ~200 million years, we conclude that the solar–climate connection was likely present during the Mesozoic era. 相似文献
18.
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. 相似文献
19.
20.
Geomagnetism and Aeronomy - The values of the radio and X-ray solar flux over the last three cycles of solar activity were studied for the presence of quasi-periodic oscillations via the... 相似文献