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1.
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...  相似文献   

2.
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.  相似文献   

3.
Geomagnetism and Aeronomy - Abstract—By comparing the moving 12-month averaged values of the F107 solar radiation flux at a wavelength of 10.7 cm and ionospheric solar activity index T, we...  相似文献   

4.
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.
An analysis of oscillatory processes with periods not shorter than several tens of minutes in three isolated sunspots, which were observed during identical periods in the optical and radio bands, is illustrated. SDO/HMI magnetograms at an interval of 45 s and radio maps at a wavelength of 1.76 cm, obtained using a Nobeyama radioheliograph (NoRH), have been used. The time profiles, which were constructed based on the NoRH and SDO/HMI data, indicate that the oscillations of the radioemission correlate with those of the sunspot magnetic field. The wavelet spectra and cross-wavelet transform reveal common oscillation periods of 30–40, 70–100, and 150–200 min. The identical oscillation periods, found using fundamentally different methods from ground-based and space observations, confirm the solar nature of these oscillations, which can be interpreted as oscillations of a sunspot as a whole.  相似文献   

6.
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   

7.
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   

8.
The influence of helio/geophysical factors on the solar energy input to the lower atmosphere has been studied at the network of actinometric stations of Russia in different latitudinal belts. It was found that there are appreciable changes in the half-yearly values of total radiation associated with galactic cosmic ray (GCR) variations in the 11-yr solar cycle, the increase of GCR flux being accompanied by a decrease of the total radiation at higher latitudes and by its increase at lower latitudes. Auroral phenomena and solar flare activity are likely to affect the solar radiation input to the high-latitudinal belt together with GCR variations, the increase of both these factors resulting in the decrease of total radiation. The changes found in the total radiation fluxes in the lower atmosphere seem to be related to the cloud cover variations associated with the solar and geophysical phenomena under study. The variations of the solar radiation input in the 11-yr-cycle amounting to ±4–6% may be an important factor affecting tropospheric dynamics.  相似文献   

9.
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...  相似文献   

10.
Based on the known forecast of solar cycle 25 amplitude (Rz max ≈ 50), the first assessments of the shape and amplitude of this cycle in the index of solar activity F10.7 (the magnitude of solar radio flux at the 10.7 cm wavelength) are given. It has been found that (F10.7)max ≈ 115, which means that it is the lowest solar cycle ever encountered in the history of regular ionospheric measurements. For this reason, many ionospheric parameters for cycle 25, including the F2-layer peak height and critical frequency (hmF2 and foF2), will be extremely low. For example, at middle latitudes, typical foF2 values will not exceed 8–10 MHz, which makes ionospheric heating ineffective in the area of upper hybrid resonance at frequencies higher than 10 MHz. The density of the atmosphere will also be extremely low, which significantly extends the lifetime of low-orbit satellites. The probability of F-spread will be increased, especially during night hours.  相似文献   

11.
Data from three solar observatories (Learmonth, Holloman, and San Vito) are used to study the variations in the average number of sunspots per sunspot group. It is found that the different types of sunspot groups and the number of sunspots in these groups have different solar cycle and cycle to cycle variations. The varying ratio between the average number of sunspots and the number of sunspot groups is shown to be a real feature and not a result of changing observational instruments, observers’ experience, calculation schemes, etc., and is a result of variations in the solar magnetic fields. Therefore, the attempts to minimize the discrepancies between the sunspot number and sunspot group series are not justified, and lead to the loss of important information about the variability of the solar dynamo.  相似文献   

12.
The average and maximal numbers of sunspot groups in the approaching solar cycle (cycle 24) have been predicted using paleoastrophysical information about solar activity during the last more than 10000 years. The linear and nonlinear prediction methods have been applied. It has been indicated that, from the standpoint of solar paleoastrophysics, the next cycle will most probably be average: the number of sunspot groups at a maximum will reach 68–101. The probability that cycle 24 will be powerful (more than 160 sunspot groups), which was predicted by some researchers, is low (not higher than 2%).  相似文献   

13.
利用我国9个电离层观测站第21和22太阳周大约20年的foF2月中值数据,分析太阳活动和地磁活动对电离层foF2的影响,结果显示白天和夏季夜间foF2和太阳黑子数R之间存在着明显非线性关系,并且随着纬度的降低逐渐增强.当回归分析加入地磁Ap指数时,多重回归模型与实测值误差进一步减小,说明同时考虑太阳活动和地磁活动的非线性影响能够更好地描述foF2的变化.基于foF2与太阳黑子数R及地磁指数Ap之间的非线性统计关系,利用Fourier级数建立9个单站谱模型,并与国际参考电离层IRI进行了比较,精度有一定提高.  相似文献   

14.
Numerical modeling of changes in the zonal circulation and amplitudes of stationary planetary waves are performed with an accounting for the impact of solar activity variations on the thermosphere. A thermospheric version of the Middle/Upper Atmosphere Model (MUAM) is used to calculate the circulation in the middle and upper atmosphere at altitudes up to 300 km from the Earth’s surface. Different values of the solar radio emission flux in the thermosphere are specified at a wavelength of 10.7 cm to take into account the solar activity variations. The ionospheric conductivities and their variations in latitude, longitude, and time are taken into account. The calculations are done for the January–February period and the conditions of low, medium, and high solar activity. It was shown that, during high-activity periods, the zonal wind velocities increases at altitudes exceeding 150 km and decreases in the lower layers. The amplitudes of planetary waves at high solar activity with respect to the altitude above 120 km or below 100 km, respectively, are smaller or larger than those at low activity. These differences correspond to the calculated changes in the refractive index of the atmosphere for stationary planetary waves and the Eliassen–Palm flux. Changes in the conditions for the propagation and reflection of stationary planetary waves in the thermosphere may influence the variations in their amplitudes and the atmospheric circulation, including the lower altitudes of the middle atmosphere.  相似文献   

15.
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 aN 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.  相似文献   

16.
The upper ionosphere electron density characterized by the critical frequency foF2 is correlated with solar activity when using monthly medians or averages from longer intervals. When shorter intervals are studied, time delays of different lengths in solar activity effects in the ionosphere are observed. The correlation between the foF2 values and the solar radiation intensity, given by the F10.7 index, is studied using the 1967–2003 data of mid-latitude ionosonde stations spaced at distances greater than 100° in geographical longitude. At which longitude the reaction of foF2 to the changes in solar activity appears sooner depends on the position of the interval studied in the 22-year solar cycle.  相似文献   

17.
An empirical model of total electron content (TEC) for a low-latitude station, Palehua, has been developed using harmonic analysis of TEC data measured at this station during the period 1980–1990; the TEC data were obtained from Faraday rotation measurements of linearly polarised signals transmitted by geostationary satellites. The analysis reveals that monthly mean values of the daily mean and the first four harmonics vary in phase with solar activity and exhibit annual, semi-annual variations and equinoctial asymmetries. A set of 81 coefficients of zero and the first four orders were determined which were found to be sufficient to model the TEC. The model strongly depends on the sunspot number. The harmonic components derived from the 81 coefficients are scaled by this property. The modelled monthly mean TEC values agree quantitatively with the measured data, the maximum deviation being limited to ±15%. The model reasonably reproduces the features observed in the diurnal, seasonal and solar cycle variations of the measured data. The annual variation of observed TEC exhibits opposite equinoctial asymmetries at solar minimum and solar maximum. Also, the mean and first four harmonics show a saturation/decreasing effect when the sunspot number exceeds about 170. The observed features are discussed qualitatively.  相似文献   

18.
Total Solar Irradiance Observations   总被引：1，自引：0，他引：1  
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.  相似文献   

19.
There are limited homogeneous instrumental observations of the sunspot magnetic fields, but the Earth is a sort of a probe reacting to interplanetary disturbances which are manifestation of the solar magnetic fields. We find correlations between some parameters of geomagnetic activity (the geomagnetic activity “floor”—the minimum value under which the geomagnetic activity cannot fall in a sunspot cycle, and the rate of increase of the geomagnetic activity with increasing sunspot number), and sunspot magnetic fields (the sunspot magnetic field in the cycle minimum, and the rate of increase of the sunspot magnetic field from cycle minimum to cycle maximum). Based on these correlations we are able to reconstruct the sunspot magnetic fields in sunspot minima and maxima since sunspot cycle 9 (mid 19th century).  相似文献   

20.
The physical conditions in the low corona and chromosphere of solar active regions are studied. A diagnostics technique based on multiwave observations in the centimeter range, photospheric magnetic field extrapolation, and radioemission calculations has been applied. The calculated spatial and spectral structure of the radioemission has been compared with RATAN-600 spectral-polarization observations with a high spatial resolution. The effect of the plasma physical parameters on the emission structure character in a complex magnetic field topology in active regions is analyzed. Modeling of the spectral singularities at a quasi-periodic propagation of the radioemission is presented.  相似文献   

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