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1.
Great magnetic storms (geomagnetic index C9 is ≥8 for St. Petersburg, which can correspond to Kp ≥ 8 or Dst < ?200 nT), registered from 1841 to 1870 at the St. Petersburg, Yekaterinburg, Barnaul, Nerchinsk, Sitka, and Beijing (at the Russian embassy) observatories are analyzed. A catalog of intensive magnetic storms during this period, which includes solar cycles 9–11, has been compiled. The statistical characteristics of great magnetic storms during this historical period have been obtained. These results indicate that high solar activity played a decisive role in the generation of very intense magnetic storms during the considered period. These storms are characterized by only one peak in a solar cycle, which was registered in the years of the cycle minimum (or slightly earlier): the number of great geomagnetic storms near the solar activity maximum was twice as large as the number of such storms during less active periods. A maximum in September–October and an additional maximum in February are observed in the annual distribution of storms. In addition, the storm intensity inversely depends on the storm duration. 相似文献
2.
E. V. Liperovskaya 《Geomagnetism and Aeronomy》2008,48(6):807-811
The observations of spread F during the nighttime hours (0000–0500 LT) have been statistically analyzed based on data of Tokyo, Akita, Wakkanai, and Yamagawa Japan vertical ionospheric sounding stations for the time intervals a month before and a month after an earthquake. The disturbances in the probability of spread F appearance before an earthquake are revealed against a background of the variations depending on season, solar activity cycle, geomagnetic and solar disturbances. The days with increased solar (Wolf number W > 100) and geomagnetic (ΣK > 30) activity are excluded from the analysis. The spread F effects are considered for more than a hundred earthquakes with magnitude M > 5 and epicenter depth h < 80 km at distances of R < 1000 km from epicenters to the vertical sounding station. An average decrease in the spread F occurrence probability one-two weeks before an earthquake has been revealed using the superposed epoch method (the probability was minimal approximately ten days before the event and then increased until the earthquake onset). Similar results are obtained for all four stations. The reliability of the effect has been estimated. The dependence of the detected effect on the magnitude and distance has been studied. 相似文献
3.
The level of wave geomagnetic activity in the morning and daytime sectors of auroral latitudes during strong magnetic storms with Dst min varying from ?100 to ?150 nT in 1995–2002 have been studied using a new ULF index of wave activity proposed in [Kozyreva et al., 2007]. It has been detected that daytime Pc5 pulsations (2–6 mHz) are most intense during the main phase of a magnetic storm rather than during the recovery phase as was considered previously. It has been indicated that morning geomagnetic pulsations during the substorm recovery phase mainly contribute to daytime wave activity. The appearance of individual intervals with the southward IMF B z component during the magnetic storm recovery phase results in increases in the ULF index values. 相似文献
4.
The annual number of magnetic storms N recorded at St. Petersburg observatories (Pavlovsk/Slutsk and Voyeykovo) in 1878–1954 is studied. The analysis shows that N has increased since ~1900 for different storm types (storms with sudden commencement Ssc and storms with gradual Sg commencement; moderate, strong and very strong); however, the number of Ssc storms increased more rapidly than the number of Sg storms. The percentage of Ssc storms doubled for the first half of the 20th century, while the number of Sg storms decreased by 1.5 times. The Ssc storms are driven by coronal mass ejections from closed magnetic structures on the Sun, and Sg storms are driven by corotating fluxes from open magnetic structures and coronal holes. These results are apparently evidence of an increase in the activity of both types of solar magnetic structures in the first half of the 20th century and a more rapid increase in the activity of fields with closed lines of forces. A semiannual variation with maxima in the periods of vernal and autumnal equinoxes is clearly pronounced for Sg and moderate storms. The tendency to have two equinoctial maxima is pronounced in the total number of storms N for both even and odd cycles; however, maxima that differ from the arithmetic mean by more than a standard deviation are observed only in September in even cycles and in March in odd cycles. 相似文献
5.
The distribution of the ionospheric currents during the geomagnetic storms of November 20–21, 2003, November 7–8, 2004, and November 9–10, 2004, depending on the IMF B y component, has been studied based on the data from the global network of magnetic stations. It has been indicated that, during geomagnetic disturbances, the westward electrojet intensity maximum is localized in the evening sector at IMF B y < 0 and in the morning sector at IMF B y > 0. The region of the westward electrojet intensity maximum shifts to morning hours with increasing positive B y values. Thus, the IMF azimuthal component forms not only the magnetospheric convection pattern during magnetic storms but is also responsible for the longitudinal position of ionospheric structures. 相似文献
6.
The period of interplanetary, geomagnetic and solar disturbances of September 7–15, 2005, is characterized by two sharp increases of solar wind velocity to 1000 km/s and great Dst variation of the geomagnetic field (~140 nT). The time variations of theoretical and experimental geomagnetic thresholds observed during this strong geomagnetic storm, their connection with solar wind parameters and the Dst index, and the features of latitudinal behavior of geomagnetic thresholds at particular times of the storm were studied. The theoretical geomagnetic thresholds were calculated with cosmic ray particle tracing in the magnetic field of the disturbed magnetosphere described by Ts01 model. The experimental geomagnetic thresholds were specified by spectrographic global survey according to the data of cosmic ray registration by the global station network. 相似文献
7.
The dependence of the correlation coefficient r(h, fo) between the stratospheric parameter h(100) and critical frequency foF2 revealed in the data of two solar cycles (1979–1989 and 1990–2000) on geomagnetic activity is analyzed. It is shown that the character of the r(h, fo) dependence on limitation on the Ap geomagnetic index is the same in both cycles but depends on the time of day and solar activity level for the given year. It is also found that there is a considerable difference in the absolute values of r(h, fo) between two cycles. 相似文献
8.
V. V. Kasinskii N. G. Ptitsyna N. N. Lyahov M. I. Tyasto G. Villoresi N. Iucci 《Geomagnetism and Aeronomy》2007,47(5):676-680
Geomagnetic variations generate electric currents in long conductors such as high-voltage lines, pipelines, and telecoms cables. The aim of our work is to study the possible effect of geomagnetic disturbances on the operation of automated systems and telemechanics of a midlatitude railroad based on the data on the malfunctions and breakdowns registered in 2004 on the East Siberian railroad (VSZhD). It has been obtained that the total daily duration of malfunctions and breakdowns (T) during disturbed periods is controlled by geomagnetic activity. When a peak of geomagnetic activity is reached during a storm, T increases about three times. Moreover, a correlation between T and the local index of geomagnetic activity (A), measured at Podkamennaya Tunguska Siberian observatory, is high during disturbed periods. Specifically, the correlation coefficient (K) is equal to 0.83 and 0.71 for the strongest two storms of 2004 that occurred in July 17–August 2 and November 4–18, respectively. 相似文献
9.
By analyzing the variations of global electron content (GEC) during geomagnetic storm events, the ratio “GEC/GECQT” is found to be closely correlated with geomagnetic Kp index and time weighted Dst index, where GECQT is the quiet time reference value. Moreover, the GEC/GECQT will decrease with the increase of the solar flux F10.7 index. Furthermore, we construct a linear model for storm-time response of GEC. Eighty-two storm events during 1999–2011 were utilized to calculate the model coefficients, and the performance of the model was tested using data of 8 storm events in 2012 by comparing the outputs of the model with the observed GEC values. Results suggest that the model can capture the characteristics of the GEC variation in response to magnetic storms. The component describing the solar activity influence shows a counteracting effect with the geomagnetic activity component; and the influence of Kp index causes an increase of GEC, while the time weighted Dst index causes a decrease of GEC. 相似文献
10.
N. V. Bakhmetieva V. D. Vyakhirev E. E. Kalinina G. P. Komrakov 《Geomagnetism and Aeronomy》2017,57(1):58-71
The results of observations in the Vasil’sursk Laboratory (56.1° N, 46.1° E) of partial solar eclipses of August 11, 1999, August 1, 2008, and March 20, 2015 are discussed. Ionospheric observations in the eclipse periods and on control days were conducted by the method of resonant scatter of radio waves at artificial periodic irregularities of the ionospheric plasma and the partial reflection method based on radio wave scatter by natural irregularities in the D region. The lower ionosphere reaction to solar eclipses, including variations in the electron concentration and characteristics of the signals scattered by APIs, was studied. An intensification of the lower ionosphere turbulization, an increase in the signal amplitudes backscattered by APIs in the E region, stratification of the D region, and the arrival of scattered signals from mesopause heights were observed during the eclipses. A decrease in the electron concentration of the D region up to a factor of 3–5 was found by the partial reflection method. Above 88 km, the ionospheric response was delayed by 20–25 min relative to the moment of the eclipse maximum phase, whereas this delay in the lower part of the D region was 2–4 min. 相似文献
11.
The results of studying the atmospheric and ionospheric variability in the region of Eastern Siberia are presented. The analysis involved data on the atmosphere temperature at mesopause heights (Tm) and vertical sounding data on the peak electron density (NmF2). The data on temperature were obtained by spectrometric observations of the hydroxyl molecule emission (band ОН (6-2), 834.0 nm, maximum emission height ~87 km). The analysis covers the period from 2008 to 2015. Seasonal and year-to-year variations in the variability of Tm and NmF2 were studied and compared in different time periods: day-to-day variations (T > 24 h), tidal variations (8 h ≤ T ≤ 24 h), and variations with periods of internal gravity waves (T < 8 h). Both common features and distinctions in the behavior of the analyzed parameters have been found, and their possible physical causes are analyzed. 相似文献
12.
S. I. Solovyev R. N. Boroyev A. V. Moiseyev A. Du K. Yumoto 《Geomagnetism and Aeronomy》2009,49(4):450-460
The regularities in the southward drift of the ionospheric current centers and luminosity boundaries during strong magnetic storms of November 2003 and 2004 (with Dst ≈ ?400 and ?470 nT, respectively) are studied based on the global geomagnetic observations and TV measurements of auroras. It has been indicated that the eastward and westward electrojets in the dayside and nightside sectors simultaneously shift equatorward to minimal latitudes of Φ min ° ～53°–55°. It has been obtained that the Φ min ° latitude decreases with increasing negative values of Dst, IMF B z component, and westward electric field strength in the solar wind. The dependence of the electrojet equatorward shift velocity (V av) on the rate of IMF B z variations (ΔB z /Δt) has been determined. It is assumed that the electrojet dynamics along the meridian is caused by a change in the structure of the magnetosphere and electric fields in the solar wind and the Earth’s magnetosphere. 相似文献
13.
Month-to-month changes in the statistical characteristics of the ionospheric E layer peak electron density NmE at medium and low geomagnetic latitudes under daytime geomagnetically quiet conditions are investigated. Critical frequencies of the ionospheric E layer measured by the middle latitude ionosonde Boulder and low latitude ionosondes Huancayo and Jicamarca at low solar activity from 1957 to 2015 have been used in the conducted statistical analysis. The mathematical expectation of NmE, standard deviation of NmE from the expectation of NmE, and NmE variation coefficient have been calculated for each month of the year. The months of the formation of extrema of these statistical parameters of NmE were found. 相似文献
14.
The F-region peak electron densities NmF2 measured during daytime quiet geomagnetic conditions at low solar activity on January 22, 2008, April 8, 1997, July 12, 1986, and October 26, 1995, are compared. Ionospheric parameters are measured by the ionosonde and incoherent scatter radar at Millstone Hill and calculated with the use of a 1D nonstationary ionosphere–plasmasphere model of number densities and temperatures of electrons and ions at middle geomagnetic latitudes. The formation of the semiannual anomaly of the midlatitudinal NmF2 under daytime quiet geomagnetic conditions at low solar activity is studied. The study shows that the semiannual NmF2 anomaly occurs due to the total impact of three main causes: seasonal variations in the velocity of plasma drift along the geomagnetic field due to the corresponding variations in the components of the neutral wind velocity; seasonal variations in the composition and temperature of the neutral atmosphere; and the dependence of the solar zenith angle on a number of the day in the year at the same solar local time. 相似文献
15.
S. V. Anisimov N. M. Shikhova N. G. Kleimenova 《Izvestiya Physics of the Solid Earth》2018,54(5):688-697
An algorithm is developed for automated detection of the short-period Pc1 geomagnetic pulsations (frequency band f = 0.2–3 Hz) from the continuous time series of digital recording during 1998–2014 at the midlatitude Borok station. A digital catalog with the indication of time intervals of the presence and main morphological characteristics of Pc1 pulsations is created. Based on this catalog, the annual, seasonal, and diurnal dynamics of the midlatitude Pc1 pulsation activity is studied for 1998–2014. It is shown that the annual variation of the Pc1 occurrence has a maximum in 2005, i.e., at the end of the solar cycle decay phase, just as in the previous cycles. It is found that the minimum of the cases of Pc1 occurrence is observed in 2009, i.e., not at the maximum, just was the case in the previous cycles, but during the deep minimum of solar activity, which testifies to the untypical conditions in the magnetosphere during the unusually long minimum of the 23rd cycle. The seasonal variation of the Pc1 occurrence has a summer minimum when the series of Pc1 pulsations occur almost thrice as rarely as in winter. Besides, there are relatively small maxima at equinox. The diurnal behavior of Pc1 pulsations has the maxima in the morning and midnight sectors of the magnetosphere. By the superposed epoch analysis technique it is established that the maximal number of the cases of occurrence of Pc1 pulsations at the Borok observatory is observed on the fourth day after the global geomagnetic disturbances. The statistical distributions of pulsations amplitude and duration are obtained. 相似文献
16.
L. I. Gromova N. G. Kleimenova A. E. Levitin S. V. Gromov L. A. Dremukhina N. R. Zelinskii 《Geomagnetism and Aeronomy》2016,56(3):281-292
The high-latitude geomagnetic effects of an unusually long initial phase of the largest magnetic storm (SymH ~–220 nT) in cycle 24 of the solar activity are considered. Three interplanetary shocks characterized by considerable solar wind density jumps (up to 50–60 cm–3) at a low solar wind velocity (350–400 km/s) approached the Earth’s magnetosphere during the storm initial phase. The first two dynamic impacts did not result in the development of a magnetic storm, since the IMF Bz remained positive for a long time after these shocks, but they caused daytime polar substorms (magnetic bays) near the boundary between the closed and open magnetosphere. The magnetic field vector diagrams at high latitudes and the behaviour of high-latitude long-period geomagnetic pulsations (ipcl and vlp) made it possible to specify the dynamics of this boundary position. The spatiotemporal features of daytime polar substorms (the dayside polar electrojet, PE) caused by sudden changes in the solar wind dynamic pressure are discussed in detail, and the singularities of ionospheric convection in the polar cap are considered. It has been shown that the main phase of this two-stage storm started rapidly developing only when the third most intense shock approached the Earth against a background of large negative IMF Bz values (to–39 nT). It was concluded that the dynamics of convective vortices and the related restructing of the field-aligned currents can result in spatiotemporal fluctuations in the closing ionospheric currents that are registered on the Earth’s surface as bay-like magnetic disturbances. 相似文献
17.
It is convenient to use the semi-empirical model (SEM), developed by the authors earlier and describing the relation of the electron density at heights of the middle ionosphere (120–200 km) to the parameters of the thermosphere and the integral flux of the ionizing solar radiation, to estimate the gas composition characteristics using the data of ionospheric measurements [Shchepkin et al., 2008]. The ratios of the concentrations of oxygen atoms and nitrogen molecules to those of oxygen molecules and atoms at a height of 120 km are compared using two SEM versions. The first version is based on the usage of the coefficients obtained from the measurements of N(h) profiles at Moscow observatory. The electron densities at heights of 120–200 km, obtained at the Institute of Solar-Terrestrial Physics in 2003–2006 using the digisonde, were the experimental data for the second version. 相似文献
18.
On the basis of the F2-layer critical frequency foF2 for the noon at some European stations for 1958–2005, it is found that the geomagnetic activity corresponding to the foF2 median is systematically lower than that averaged over the month; the difference increases with an increase in latitude. Moreover, the dispersion of geomagnetic activity for the foF2 median at relatively high latitudes is lower than at middle latitudes. These regularities are related to the fact that high geomagnetic activity usually leads to a distinct deviation of foF2 from the typical average value, i.e., from the foF2 median, and such deviation is more substantial at relatively high latitudes. That is why the geomagnetic activity for the foF2 median is lower at relatively high latitudes than at middle latitudes. 相似文献
19.
The dependence of the zonal geomagnetic indices (AE, Ap, Kp, Kn, and Dst) on the solar wind parameters (the electric field E y component, dynamic pressure P d and IMF irregularity σB) has been studied for two types of events: magnetic clouds and high-speed streams. Based on the empirical relationships, it has been established that the AE, Ap, Kp, and Kn indices are directly proportional to the E y value at E y < 12 mV m?1 and are inversely proportional to this value at E y > 12 mV m?1 for the first-type events. On the contrary, the dependence of Dst on E y is monotonous nonlinear. A linear dependence of all geomagnetic indices on E y is typical of the second-type events. It has been indicated that the specific features of geoeffectiveness of magnetic clouds and high-speed solar wind streams are caused by the dependence of the electric field potential across the polar cap on the electric field, solar wind dynamic pressure, and IMF fluctuations. 相似文献
20.
G. A. Mikhailova Yu. M. Mikhailov O. V. Kapustina S. E. Smirnov 《Geomagnetism and Aeronomy》2009,49(2):247-251
The dynamics of wave disturbances in the ionospheric E region in the band of periods of thermal tidal waves and waves of planetary scales (T = 48, 72, and 192 h) has been studied based on the variations in the horizontal component of the geomagnetic field, observed at Paratunka and Barrow observatories in September–October 1999. It has been found that, at midlatitudes during high geomagnetic activity, the intensity of oscillations in the power spectra with T = 24 and 12 h varies with a periodicity of 16 days different from the periodicity of changes in the ΣKp index. The maximal deviations of these periods from the values under quiet conditions coincide with the maximal changes in the ΣKp index. The variations in the 48–192 h band of periods (especially with T ～192 h) intensify simultaneously with increasing geomagnetic activity. The intensity of this harmonic is several times as high as that of the harmonic with T ～ 24 h. The periodicity of changes in the harmonics intensity within the 48–192 h band coincides with the periodicity of changes in the ΣKp index. In the polar ionosphere, the effect of high geomagnetic activity is observed as an increase in the variations with a quasi-period of T ～ 24 h and as an appearance of variations in the 48–192 h band with the periodicity coinciding with the maximums in the ΣKp index variations. 相似文献