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1.
The correlation between geomagnetic activity and the sunspot number in the 11-year solar cycle exhibits long-term variations due to the varying time lag between the sunspot-related and non-sunspot related geomagnetic activity, and the varying relative amplitude of the respective geomagnetic activity peaks. As the sunspot-related and non-sunspot related geomagnetic activity peaks are caused by different solar agents, related to the solar toroidal and poloidal fields, respectively, we use their variations to derive the parameters of the solar dynamo transforming the poloidal field into toroidal field and back. We find that in the last 12 cycles the solar surface meridional circulation varied between 5 and 20 m/s (averaged over latitude and over the sunspot cycle), the deep circulation varied between 2.5 and 5.5 m/s, and the diffusivity in the whole of the convection zone was ～108 m2/s. In the last 12 cycles solar dynamo has been operating in moderately diffusion dominated regime in the bulk of the convection zone. This means that a part of the poloidal field generated at the surface is advected by the meridional circulation all the way to the poles, down to the tachocline and equatorward to sunspot latitudes, while another part is diffused directly to the tachocline at midlatitudes, “short-circuiting” the meridional circulation. The sunspot maximum is the superposition of the two surges of toroidal field generated by these two parts of the poloidal field, which is the explanation of the double peaks and the Gnevyshev gap in sunspot maximum. Near the tachocline, dynamo has been operating in diffusion dominated regime in which diffusion is more important than advection, so with increasing speed of the deep circulation the time for diffusive decay of the poloidal field decreases, and more toroidal field is generated leading to a higher sunspot maximum. During the Maunder minimum the dynamo was operating in advection dominated regime near the tachocline, with the transition from diffusion dominated to advection dominated regime caused by a sharp drop in the surface meridional circulation which is in general the most important factor modulating the amplitude of the sunspot cycle. 相似文献
2.
Yu. S. Shugay I. S. Veselovsky O. S. Yakovchouk I. N. Myagkova 《Geomagnetism and Aeronomy》2014,54(5):558-567
The relativistic electron flux in the Earth’s outer radiation belt generally decreased by almost three orders of magnitude during the minimum of cycle 23 in 2009. Such a behavior was possibly caused by very low geomagnetic activity during an extremely weak interplanetary field in that period. This decrease was replaced by an increase in the relativistic electron flux by two orders of magnitude during several months after the sunspot minimum at the beginning of 2010. 相似文献
3.
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. 相似文献
4.
This work investigated an interrelationship between the monthly means of time derivatives of horizontal geomagnetic field, dH/dt, sunspot number, R z , and aa index for the period of substorms (from ?90 to ?1800 nT) during the years 1990–2009. A total of 232 substorms were identified during the period of study. The time derivative of horizontal geomagnetic field, dH/dt, used as a proxy for geomagnetically induced current (GIC) exhibited high positive correlation with sunspot number (0.86) and aa index (0.8998). The obtained geomagnetic activity is in 92.665% explicable by the combined effect of sunspot number and aa index. The distribution of substorms as a function of years gives a strong support for the existence of geomagnetic activity increases, which implies that as the sunspot number increases the base level of geomagnetic activity increases too. 相似文献
5.
本文利用南极中山站和新奥尔松（NAL）等5个北极站2000年9月到2003年3月共719天的地磁观测数据，以20 min间隔内地磁北向水平分量的互相关系数大于09为判据，对南北极地磁活动相关的发生率进行了统计，并与T89地磁模型得到的中山站共轭位置的分布进行了比较. 结果表明，南北极地磁活动相关的发生率与台站位置、季节、地方时和地磁活动性有着密切的关系. 在北极的5个台站中朗伊尔站（LYR）与中山站地磁相关的时间最多（占17%）；在两分季发生相关的情况比冬季和夏季多；在傍晚发生相关的情况最多，中午发生相关的情况最少；地磁活动较强时，相关的情况比地磁宁静时更多一些. 相似文献
6.
I. A. Bilenko 《Geomagnetism and Aeronomy》2016,56(8):978-986
We compare changes in the solar global magnetic field (GMF) given by the distribution of magnetic fields on the source surface and spot activity characterized by Wolf numbers, the number of spots, and their area reflecting the dynamics of local magnetic fields of active regions during cycles 21 to 24 (1976–2015). The results indicate that the changes in the GMF and spot activity have certain differences, both in different cycles generally and in the phases of growth, maximum, and decline in each individual cycle. The maximum and minimum correlations between the GMF and spot activity are observed in cycles 22 and 24, respectively. The maximum correlation is reached in growth phases (cycles 21, 22, and 24) and in the phase of decline (cycle 23), which can be associated with the fact that the phase of decline in cycle 23 is anomalously extended. Almost no correlation between the GMF and spot activity can be found at the phases of the maximum and early beginning of decline in all cycles. This can be associated with structural reorganization and sign change in the GMF. 相似文献
7.
It has been indicated that special moments (turning points), when certain characteristics of the latitudinal (equatorward) drift of the sunspot drift zone suddenly change, exist in each 11-year solar cycle. The moment when a sunspot formation low-latitude boundary minimum (T2), coordinated in time with the end of a polar magnetic field polarity reversal, exists has a special place among these points. A conclusion has been drawn that it is impossible to reconstruct polarity reversal moments in the past based on information about turning points T2. The average velocities of the latitudinal drift of the minimal, average, and maximal sunspot group latitudes have been calculated. It has been indicated that the closeness of the relationship between the first two velocities and the maximal activity amplitudes in the cycles differ substantially for the first (before point T2) and second (after point T2) cycle parts. The corresponding values of the correlation coefficients increase substantially in the second cycle (after point T2). It has been established that a relationship exists between some velocities calculated in these cycles and the activity amplitudes at maximums of the next cycles. A model for predicting future cycle maximums has been constructed based on this conclusion. The probable average annual Wolf number at a maximum of cycle 24 has been determined (W(24) = 93). 相似文献
8.
本文利用2000年至2009年CHAMP卫星朗缪尔探针实地测量的电子密度数据,分析了电离层中纬槽的位置变化及其控制因素.研究结果表明:(1)地磁平静期电离层中纬槽的位置随磁地方时和经度变化;(2)电离层中纬槽的位置对地理经度的依赖表现为西半球槽的位置高于东半球;(3)AE指数和SYM-H指数与槽的位置变化显著相关,表明极光电集流和环电流是中纬槽位置变化的重要控制因素;(4)太阳风电场晨-昏分量的量值变化显著影响中纬槽位置,而其极性变化的影响相对较弱.研究结果对中纬槽建模有一定的参考价值. 相似文献
9.
We study the annual frequency of occurrence of intense geomagnetic storms (Dst < –100 nT) throughout the solar activity cycle for the last three cycles and find that it shows different structures. In cycles 20 and 22 it peaks during the ascending phase, near sunspot maximum. During cycle 21, however, there is one peak in the ascending phase and a second, higher, peak in the descending phase separated by a minimum of storm occurrence during 1980, the sunspot maximum. We compare the solar cycle distribution of storms with the corresponding evolution of coronal mass ejections and flares. We find that, as the frequency of occurrence of coronal mass ejections seems to follow very closely the evolution of the sunspot number, it does not reproduce the storm profiles. The temporal distribution of flares varies from that of sunspots and is more in agreement with the distribution of intense geomagnetic storms, but flares show a maximum at every sunspot maximum and cannot then explain the small number of intense storms in 1980. In a previous study we demonstrated that, in most cases, the occurrence of intense geomagnetic storms is associated with a flaring event in an active region located near a coronal hole. In this work we study the spatial relationship between active regions and coronal holes for solar cycles 21 and 22 and find that it also shows different temporal evolution in each cycle in accordance with the occurrence of strong geomagnetic storms; although there were many active regions during 1980, most of the time they were far from coronal holes. We analyse in detail the situation for the intense geomagnetic storms in 1980 and show that, in every case, they were associated with a flare in one of the few active regions adjacent to a coronal hole. 相似文献
10.
11.
I. A. Bilenko 《Geomagnetism and Aeronomy》2009,49(8):1113-1114
The sources of geomagnetic disturbances during 1999–2003 are discussed. The relation between geomagnetic activity and the
rate of coronal mass ejections (CMEs), their parameters, and the dynamics of solar photospheric magnetic fields is considered.
It is shown that during the reorganization of unipolar regions of the photospheric magnetic field, the number of CMEs increases
and their parameters change. The geomagnetic disturbance level also increases in these periods. 相似文献
12.
本文根据苏黎世天文台太阳黑子11年周期资料和太阳黑子磁场磁性变化周期特征，构建了太阳黑子磁场磁性指数MI(Magnetic Index)时间序列.分析表明：太阳活动磁性周期平均长度为222年，但是每个周期长度是不相等的；多数情况周期短时磁性指数较大，对应太阳活动水平强；周期变长时磁性指数较小，对应太阳活动水平较弱；太阳黑子磁场磁性指数序列也具有80～90年的世纪周期. 进一步研究指出，太阳黑子磁场磁性指数曲线由极小值升至极大值时期，太阳磁场南向，行星际磁场磁力线与地磁场磁力线重联，此时磁层为开磁层，太阳风将携带大量等离子体从向阳面进入地球磁层，从而使输入的动量、能量和物质大幅度增加，与北半球对流层增温时期对应；太阳黑子磁场磁性指数曲线由极大值下降至极小值时期，太阳磁场北向，与磁层顶地磁场同向，行星际磁场不会与地磁场发生重联，此时磁层为闭磁层，这种情况下，只有少数带电粒子能够穿越磁力线进入地球磁层，与北半球对流层降温时期对应. 相似文献
13.
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
14.
B. Kirov V. N. Obridko K. Georgieva E. V. Nepomnyashtaya B. D. Shelting 《Geomagnetism and Aeronomy》2013,53(7):813-817
Geomagnetic activity in each phase of the solar cycle consists of 3 parts: (1) a “floor” below which the geomagnetic activity cannot fall even in the absence of sunspots, related to moderate graduate commencement storms; (2) sunspot-related activity due to sudden commencement storms caused by coronal mass ejections; (3) graduate commencement storms due to high speed solar wind from solar coronal holes. We find that the changes in the “floor” depend on the global magnetic moment of the Sun, and on the other side, from the height of the “floor” we can judge about the amplitude of the sunspot cycle. 相似文献
15.
Yu. A. Fursyak 《Geomagnetism and Aeronomy》2016,56(7):930-937
Specific features of the magnetic configuration, morphological structure, dynamics, and evolution of sunspot groups of the current (24th) cycle of solar activity with high flare activity are considered. The gradients of longitudinal magnetic fields at places of δ-configuration are calculated. The main finding is a time delay of 24–30 h between the time when the magnetic field gradient reaches a critical level of 0.1 G/km and the time when the first of powerful flares occurs in the active region. The study is based on data from the SDO and GOES-15 spacecrafts and ground-based solar telescopes (TST-2 at the Crimean Astrophysical Observatory of the Russian Academy of Sciences and the 150-foot telescope at the Mount Wilson Observatory). 相似文献
16.
A. G. Tlatov 《Geomagnetism and Aeronomy》2013,53(8):953-956
Relative variations in the number of sunspots and sunspot groups in activity cycles have been analyzed based on data from the Kislovodsk Mountain Astronomical Station and international indices. The following regularities have been established: (1) The relative fraction of small sunspots decreases linearly and that of large sunspots increase with increasing activity cycle amplitude. (2) The variation in the average number of sunspots in one group has a trend, and this number decreased from ～12 in cycle 19 to ～7.5 in cycle 24. (3) The ratio of the sunspot index (Ri) to the sunspot group number index (G gr) varies with a period of about 100 years. (4) An analysis of the sunspot group number index (G gr) from 1610 indicates that the Gnevyshev-Ohl rule reverses at the minimums of secular activity cycles. (5) Ratio of the total area to area of Ssp/Sum nuclei has long-term variation with a period approximately 8 cycles. Minimum ratio falls on 16–17 cycles of activity. (6) It has been indicated that the magnetic field intensity and sunspot area in the current cycle are related to the amplitude of the next activity cycle. 相似文献
17.
The sun was very active in the declining phase of solar cycle 23. Large sunspot active regions gave origin to multiple flare and coronal mass ejection (CME) activity in the interval 2003–2005. On November 2004, the active region AR 10696 was the origin of dozens of flares and many CMEs. Some events of this solar activity region resulted in two large geomagnetic storms, or superstorms (Dst??250 nT) on November 8, peak Dst=?373 nT, and on November 10, peak Dst=?289 nT. It is the purpose of this article to identify the interplanetary origins of these two superstorms. The southward-directed interplanetary magnetic fields (IMF Bs) that caused the two superstorms were related to a magnetic cloud (MC) field for the first superstorm, and a combination of sheath and MC fields for the second superstorm. However, this simple, classic picture is complicated by the presence of multiple shocks and waves. Six fast-forward shocks and, at least, two reverse waves were observed in the period of the two superstorms. A detailed analysis of these complex interplanetary features is performed in this work. 相似文献
18.
We study and compare characteristics of the sunspot group latitude distribution in two catalogs: extended Greenwich (1874–2014) and Schwabe (1825–1867) (Arlt et al., 2013). We show that both datasets reveal similar correlations between the latitude and amplitude characteristics of the 11-year cycle: the latitude dispersion correlates with the current activity and the sunspot mean latitude at the cycle’s maximum is proportional to its amplitude. This agrees with the conclusions drawn in (Ivanov et al., 2011; Ivanov and Miletsky, 2014) for the Greenwich catalog. We show that the latitude properties of the sunspot distribution are much more tolerant to gaps in observational data than traditional amplitude indices of activity. Therefore, the discovered correlations can be used for estimation of the observation quality and independent normalization of the activity levels in spotty pre-Greenwich data. We exemplified this using the Schwabe catalog. In addition, we show that the first part of the Schwabe data probably contains errors in sunspot latitudes, which lead to overestimation of the sunspot latitude dispersions. 相似文献
19.
Minimum extreme temperature variability from five meteorological stations in the central part of Mexico covering a period from 1920 to 1990 is examined. We found a correlation coefficient (r=0.65) between these temperature records and geomagnetic activity. Furthermore, by performing spectral analysis peaks were obtained with similar periodicities to those found in the sunspot number, the magnetic solar cycle, cosmic ray fluxes and geomagnetic activity; all of these phenomena are modulated by solar activity. Signals with periodicities comparable to those observed in El Niño and the Quasi-Biennial Oscillation were also identified. We conclude that the solar signal is probably present in the minimum extreme temperature record of the central part of Mexico. 相似文献
20.
本文对比分析了太阳活动高、低年期间高纬日侧顶部电离层离子上行随地磁活动水平的变化特征.按地磁活动水平,将DMSP卫星在太阳活动高年（2000-2002年,F13和F15）及太阳活动低年（2007-2009年,F13;2007-2010年,F15）期间的SSIES离子漂移速度观测数据分为三组：地磁平静期（Kp<3）,中等地磁扰动期（3 ≤ Kp < 5）和强地磁活动期（Kp ≥ 5）,分别统计分析了高纬日侧顶部电离层离子上行特征的时空分布.对比分析发现：（1）太阳活动低年期间,高纬日侧电离层离子上行发生率以及上行速度峰值均是太阳活动高年的2倍多,而离子上行通量峰值只有高年的1/6-1/4;（2）在相同太阳活动条件下,地磁活动水平对日侧电离层离子上行发生率峰值的影响并不明显,但对离子上行发生率的空间分布有着显著的控制作用：电离层离子上行高发区随地磁活动向低纬度扩展,并在强地磁活动期间呈现饱和的趋势;（3）日侧顶部电离层等离子体似乎存在两个效率相当的上行区域,一个位于极尖/极隙区纬度附近,离子可沿开放磁力线上行进入磁尾;另一个位于晨侧亚极光区附近,离子沿闭合磁力线上行,有可能进入日侧等离子体层边界层. 相似文献