共查询到20条相似文献，搜索用时 9 毫秒
1.
Possible correlation between variations of the intensity of lightnings, which are estimated from the flux of thunderstorm-generated
VLF-signals, and variations of the solar wind parameters has been investigated. The signals representing the intensity of
local thunderstorms in summer and winter are received in Yakutsk (the Eastern Siberia) and in the African World Thunderstorm
Center, respectively. The highest correlation coefficient has been obtained between the thunderstorm activity and variations
of the solar-wind particle density. This correlation has a season-dependent sign-alternating character. The maximum positive
and negative correlation coefficients are observed in August–September and February, respectively; i.e., the manifestation
of solar wind density variations in the thunderstorm activity is maximal in the near-equinoctial periods. This may be associated
with the peculiarities of the transfer of the magnetospheric electric field “from morning to evening,” which is induced by
the solar-wind particle flux, to ionospheric heights. 相似文献
2.
G. I. Druzhin V. N. Uvarov V. A. Mullayarov V. I. Kozlov A. A. Korsakov 《Geomagnetism and Aeronomy》2010,50(2):211-218
The effect of the solar eclipse that occurred on August 1, 2008, on the level of the natural electro-magnetic emission signals
in the ELF-VLF range, simultaneously observed at Kamchatka and in Yakutsk, and the variations in the amplitude and phase of
signals from the VLF radiostations, registered in Yakutsk, has been considered. The VLF radiostations in Krasnodar, Novosibirsk,
and Khabarovsk successively emitted signals at frequencies of 11 905, 12 649, and 14 880 Hz. Based on the observations of
the signals from these radiostations, it has been established that the signal amplitudes and phases increased by 3–5% and
30°–45° when the signals crossed the lunar shadow region. The synchronous registration of the ELF-VLF noise emission indicated
that a bay-like increase and the following decrease in the emission to the background level was observed at both receiving
points during the eclipse from ∼1000 to 1130 UT. This effect was registered at frequencies of 0.6–5.6 kHz in Yakutsk and at
lower (30–200 Hz) and higher (2.5–11 kHz) frequencies at Kamchatka. In this case the noise emission intensity maximum was
observed when the lunar shadow maximally approached the registration point. At higher frequencies, the emission maximum was
observed simultaneously at both points (at 1100 UT) but with a delay relative to the maximum at lower frequencies. The possible
causes of the appearance of the solar eclipse effects in the natural ELF-VLF emission are considered. 相似文献
3.
The effects of the solar eclipse of March 29, 2006, in the signals of ULF radio stations, in the intensity of regular radio noise at frequencies of 0.3–10 kHz, and in the number of atmospherics received in Yakutsk mostly from the west have been considered. The observations were performed using a multichannel parallel analyzer-recorder (11 channels in the frequency band 0.47–8.7 kHz), one-point lightning direction and range finder (0.3–100 kHz), narrow-sector radio noise direction-finder (0.3–10 kHz), recorder of signals from VLF radio stations, and broadband radio noise recorder (0.3–100 kHz). A GPS clock was used to synchronize a recorder of signals from VLF radio stations. The effect was observed in radio signals, radio noise, and number of atmospherics from the direction 270° ± 20° counted off clockwise from the north during the last stage of the eclipse (～ 1100–1200 UT), when the lunar shadow approached the line of the nighttime terminator and obscured part of the signal propagation path. The effect was observed as an enhancement of the received signals by a factor of ～1.2, a factor of ～1.4 increase in the number of atmospherics, and a change in the radio station phase values. 相似文献
4.
Seasonal and year-to-year variability in the intensity of the 557.7 nm line of atomic oxygen atmospheric emission and its
dependence on solar activity in the 23rd solar cycle is considered. The experimental data of the 557.7 nm emission observations
in Eastern Siberia obtained in 1997–2008 and the NRLMSIS-00 atmospheric model are used. For particular considered characteristics
of the 557.7 nm emission, differences between the experimental data and model approximations for the 23rd solar cycle are
noted. Possible causes of the discovered discrepancies are discussed. 相似文献
5.
V. I. Larkina 《Geomagnetism and Aeronomy》2010,50(3):320-328
The complex geophysical pattern of the development of geomagnetic storm in VLF emissions has been studied based on the satellite
data. It has been established that the variations in the LF noise emission intensity (0.1–20.0 kHz) and the energetic electron
(E ≥ 40 keV) flux density reflect the processes of magnetospheric plasma reconstruction during geomagnetic disturbances. It
has been indicated that a distinct structure of the inner and outer radiation belts is observed under quiet conditions, and
the VLF emission maximum was registered at L = 4–5. The inner boundary of the outer radiation belt shifted to lower latitudes, the intensity of the noise VLF emissions
increased, and the intensity maximum was displaced to L = 2.5–3.5 during the geomagnetic storm, when the energetic electron flux density increased. The VLF noise spectrum widened
toward higher frequencies. The VLF noise level continued increasing, the noise maximum shifted to L = 4–5, and the fluxes of precipitating electrons abruptly increased during the storm recovery phase, when the density of
the flux of quasitrapped electrons remained increased for a long time. 相似文献
6.
A. V. Mikhalev 《Geomagnetism and Aeronomy》2010,50(8):1021-1024
The effect of anomalously high average nighttime intensities of the atomic oxygen 557.7-nm atmospheric emission (luminescence
heights 85–115 km) during sudden winter stratospheric warming events (SWEs) in Eastern Siberia is considered. Analysis of
the variations in the 557.7-nm emission intensity (I
557.7) revealed the interdaily I
557.7-nm variations during SWEs and high average monthly I
557.7-nm values in the winter months in conditions of high solar activity. It has finally been found that the variations with periods
of several days, at a maximum of which anomalously high daily values of I
557.7 are observed, are superposed on the average I
557.7-level during SWEs at high solar activity. A high average level of I
557.7 in the winter months in Eastern Siberia can be related to the fact that the atomic oxygen concentration at altitudes of the
557.7 nm emission luminescence increases by a factor of 2–3 in years of high solar activity. 相似文献
7.
A. A. Egoshin V. M. Ermak Yu. I. Zetzer S. I. Kozlov V. P. Kudryavtsev A. N. Lyakhov Yu. V. Poklad E. N. Yakimenko 《Izvestiya Physics of the Solid Earth》2012,48(3):275-286
The statistical characteristics of the intensity of VLF-LF radio signals transmitted from the midlatitude radio stations and
recorded by the receiver at the Mikhnevo geophysical observatory (54.94°N, 37.73°E; Institute of Geosphere Dynamics, Russian
Academy of Sciences) in 2007–2010 are analyzed. The experiments revealed strong variations in the intensity of radio signals
during the deep solar minimum conditions, when the medium does not experience impacts from above associated with solar and
geomagnetic activity. We relate the observed variations to the disturbances from below, which are caused by the meteorological
and wave processes occurring in the lower atmosphere. 相似文献
8.
L. A. Hajkowicz 《Annales Geophysicae》1998,16(12):1573-1579
Statistical study on the universal time variations in the mean hourly auroral electrojet index (AE-index) has been undertaken for a 21 y period over two solar cycles (1957–1968 and 1978–1986). The analysis, applied to isolated auroral substorm onsets (inferred from rapid variations in the AE-index) and to the bulk of the AE data, indicates that the maximum in auroral activity is largely confined to 09–18 UT, with a distinct minimum at 03–06 UT. The diurnal effect was clearly present throughout all seasons in the first cycle but was mainly limited to northern winter in the second cycle. Severe storms (AE > 1000 nT) tended to occur between 9–18 UT irrespective of the seasons whereas all larger magnetic disturbances (AE > 500 nT) tended to occur in this time interval mostly in winter. On the whole the diurnal trend was strong in winter, intermediate at equinox and weak in summer. The implication of this study is that Eastern Siberia, Japan and Australia are mostly at night, during the period of maximum auroral activity whereas Europe and Eastern America are then mostly at daytime. The minimum of auroral activity coincides with near-midnight conditions in Eastern America. It appears that the diurnal UT distribution in the AE-index reflects a diurnal change between interplanetary magnetic field orientation and the Earths magnetic dipole inclination. 相似文献
9.
Victor U. Chukwuma 《Acta Geophysica》2007,55(4):469-489
A study of the geomagnetic storm of July 13–14, 1982, and its ionospheric response is presented using the low-latitude magnetic
index, Dst, and interpreted using solar wind interplanetary data: proton number density, solar wind flow speed, interplanetary magnetic
field southward component B
Z
, and solar wind dynamic pressure. The F2 region structure response to the geomagnetic storm was studied using foF2 data obtained during the storm from a network of various ionosonde stations. Our results appear to show simultaneous abrupt
depletion of foF2 that occurred at all latitudes in both the East Asian and African/European longitudinal zone during the period: 18:00–19:00
UT on July 13 and is as result of an abrupt increase in the dynamic pressure between 16:00 and 17:00 UT. The dynamic pressure
increased from 3.21 to 28.07 nPa within an hour. The aforementioned abrupt depletion of foF2 simultaneously resulted in an intense negative storm with peak depletion of foF2 at about 19:00 at all the stations in the East Asian longitudinal zone. In the African/European longitudinal zone, this simultaneous
abrupt depletion of foF2 resulted in intense negative storm that occurred simultaneously at the low latitude stations with peak depletion at about
20:00 UT on July 13, while the resulting negative storm at the mid latitude stations recorded peak depletion of foF2 simultaneously at about 2:00 UT on July 14. The present results indicate that most of the stations in the three longitudinal
zones showed some level of simultaneity in the depletion of foF2 between 18:00 UT on July 13 and 2:00 UT on July 14. The depletion of foF2 during the main phase of the storm was especially strongly dependent on the solar wind dynamic pressure. 相似文献
10.
《Journal of Atmospheric and Solar》2007,69(13):1513-1523
In this study, the variations of average amplitude of the very-low-frequency (VLF) signal thunderstorm origin propagating over areas of strong (magnitude >5) earthquakes are considered. Despite the non-stationary state of thunderstorms, a decrease in the amplitude of its VLF signals was usually detected 3–6 days before an earthquake, with subsequent recovery on the day of the event. The effect is similar to the attenuation of the signal amplitude of low-frequency radio stations that is observed for several days before the occurrence of an earthquake. These influences of earthquakes on thunderstorm VLF signals are recorded along different paths (different azimuths and different distances to the earthquake epicenter). The probability that an earthquake of strong magnitude will induce changes in the thunderstorm VLF signal is 60–70%. 相似文献
11.
N. G. Kleimenova O. V. Kozyreva J. Manninen T. Raita T. A. Kornilova I. A. Kornilov 《Geomagnetism and Aeronomy》2011,51(6):730-740
A complex of geophysical phenomena (geomagnetic pulsations in different frequency ranges, VLF emissions, riometer absorption,
and auroras) during the initial phase of a small recurrent magnetic storm that occurred on February 27–March 2, 2008, at a
solar activity minimum has been analyzed. The difference between this storm and other typical magnetic storms consisted in
that its initial phase developed under a prolonged period of negative IMF B
z
values, and the most intense wave-like disturbances during the storm initial phase were observed in the dusk and nighttime
magnetospheric sectors rather than in the daytime sector as is observed in the majority of cases. The passage of a dense transient
(with N
p
reaching 30 cm−3) in the solar wind under the southward IMF in the sheath region of the high-speed solar wind stream responsible for the discussed
storm caused a great (the AE index is ∼1250 nT) magnetospheric substorm. The appearance of VLF chorus, accompanied by riometer absorption bursts and Pc5
pulsations, in a very long longitudinal interval of auroral latitudes (L ∼ 5) from premidnight to dawn MLT hours has been detected. It has been concluded that a sharp increase in the solar wind
dynamic pressure under prolonged negative values of IMF B
z
resulted in the global (in longitude) development of electron cyclotron instability in the Earth’s magnetosphere. 相似文献
12.
N.R. Rigozo M.P. Souza Echer H. Evangelista D.J.R. Nordemann E. Echer 《Journal of Atmospheric and Solar》2011,73(11-12):1294-1299
The prediction of solar activity strength for solar cycles 24 and 25 is made on the basis of extrapolation of sunspot number spectral components. Monthly sunspot number data during the 1850–2007 interval (solar cycles 9–23) are decomposed into several levels and searched for periodicities by iterative regression in each level. For solar cycle 24, the peak is predicted in November 2013 with a sunspot number of 113.3. The cycle is expected to be weak, with a length of 133 mo (months) or 11.1 yr. The sunspot number maximum in cycle 25 is predicted to occur in April 2023 with a sunspot number 132.1 and a solar cycle length of 118 mo or 9.8 yr. Thus, solar cycle 24 is predicted to have an intensity 23% lower than cycle 23, and cycle 25 will be 5% lower than cycle 23. 相似文献
13.
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
14.
15.
Relationship between phases of quasi-decadal oscillations of total ozone and the 11-year solar cycle
K. N. Visheratin 《Geomagnetism and Aeronomy》2012,52(1):94-102
Temporal variability of the relationship between the phases of quasi-decadal oscillations (QDOs) of total ozone (TO), measured
at the Arosa station, and the Ri international sunspot number have been analyzed for the period of 1932–2009. Before the 1970s, the maximum phase of ozone
QDOs lagged behind solar activity variations by about 2.5–2.8 years and later outstripped by about 1.5 years. We assumed that
the TO QDOs in midlatitudes of the Northern Hemisphere were close to being in resonance with solar activity oscillations in
the period from the mid-1960s to the mid-1970s and assessed the characteristic delay period of TO QDOs. The global distribution
of phases and amplitudes of TO QDOs have been studied for the period from 1979 to 2008 based on satellite data. The maximum
phase of TO QDOs first onsets in northern middle and high latitudes and coincides with the end of the growth phase of the
11-year solar cycle. In the tropics, the maximum oscillation phase lags behind by 0.5–1 year. The maximum phase lag near 40–50°
S is about two years. The latitudinal variations of the phase of TO QDOs have been approximated. 相似文献
16.
G. A. Mikhailova Yu. M. Mikhailov O. V. Kapustina S. E. Smirnov 《Geomagnetism and Aeronomy》2010,50(6):814-823
We have performed a spectral analysis of variations in the E
z
component of a quasistatic electric field in the atmospheric surface layer in a wide band of internal gravity waves (from
5 min to 3 h) for quiet and seismically active conditions as well as high thunderstorm activity. Observational data of the
field for September, 1999 and August–September, 2002, were used. It has been shown that, if there are no thunderstorms or
earthquakes, the background spectrum includes oscillations with maxima at periods of T ∼ 1.8 and 1 h, 40, 30, 15, and 10–13 min. Their intensity in the range of periods of 0.5–3.0 h is two or more orders of magnitude
higher than the intensity of maxima in the range of 5–30 min. Before earthquakes, with anomalies in diurnal variations of
field intensity, there is a tendency of increased background spectrum at maxima noted there. In both ranges of oscillation
periods, the spectral intensity increases by one to one and a half orders of magnitude. Under high thunderstorm activity,
the variability is higher as compared to the spectra of earthquake precursors by both locations of maxima and their intensity.
The intensity of maxima exceeds the maxima on the eve of earthquakes one to one and a half orders of magnitude in the range
of periods 0.5–3.0 h and two and more orders of magnitude in the range of periods 5–30 min. 相似文献
17.
L. A. Hajkowicz 《Annales Geophysicae》1996,14(9):906-916
The equatorial ionospheric response to 228 isolated, rapid-onset auroral substorms (as defined from the auroral electrojet index AE) was found from enhancements of the virtual (minimum) height of the F-region (h′F) in the declining phase of a solar cycle (1980-85). The responses, found for three longitudinal sectors at the equator: Africa (Ouagadougou and Dakar), Asia (Manila) and America (Huancayo), were compared with the response close to the auroral source region at Yakutsk (northern Siberia). The auroral substorm onsets were centered at 17 and 15 UT at sunspot maximum (1980-82) and minimum (1983-85), preceding by 3–5 h the period of post-sunset height rise in the African sector whereas other sectors were in the early afternoon (Huancayo) and morning (Manila). The African response, particularly at Ouagadougou, was distinctly different from other sectors. In the sunspot maximum years (1980-81) the auroral surges were followed after about 3 h by a sharp depression (h′F<0) in the post-sunset height rise, with a period of little or no response (h′F=0) in 1982. A response polarity reversal (h′F>0) was noted in this sector for sunspot minimum (1983-85) when large h′F enhancements were observed at the sunset region. The responses in the Asian and American sector were positive except for a case in Huancayo when response was negative, following an auroral surge before the sunset at this station. It appears that the aurorally generated large-scale travelling ionospheric disturbances (LSTIDs), which first cause positive height enhancements in a sub-auroral location (Yakutsk), subsequently affect the unstable post-sunset ionosphere in the equatorial Africa. 相似文献
18.
Microseismic noise was studied in the frequency range 0.5–30 Hz in the conditions prevailing in the town of Vorkuta. A seismic
noise model was developed consisting of power spectral densities of ground motion velocity separately for daytime and nighttime
in different frequency ranges. The absolute noise level for frequencies of 1–5 Hz in Vorkuta varies between −140 and −150
dB in daytime and from −152 to −158 dB in nighttime, with the ranges for the 8-15 Hz noise being −140 to −155 dB in daytime
and −155 to −165 dB in nighttime. Well-pronounced daily variations in noise amplitude were observed in the frequency ranges
1.5–3 Hz and 14–17 Hz. The noise amplitude varies by 7 dB over 24 hours, with the amplitude of horizontal component variation
being 5 dB above that of the vertical component. The power spectral densities of ground motion velocity in the microseismic
noise involve several spectral peaks, whose central frequencies did not vary by more than 0.15 Hz during the entire period
of instrumental observation. The seismic background in the town of Vorkuta contains seismic events due to distant earthquakes
and local industrial explosions. 相似文献
19.
The effect of climate on the present-day formation conditions of the regimes of annual and base runoff in Eastern Siberia
rivers and changes in those regimes are studied. The significant climate warming in Eastern Siberia in recent decades is shown
to be accompanied by not only an increase in air temperature and some increase in precipitation, but also by a considerable
changes in the annual and seasonal values of river and groundwater runoff. Hydrometeorological data are used to analyze variations
in the mean annual and mean base runoff over the entire observation period divided into subperiods of 1940–1969 and 1970–2005.
Plots, diagrams, and tables are constructed for the most representative gauges. The zoning of the territory by the runoff
formation conditions was carried out and new estimates were derived for total water resources and natural groundwater resources
for 1970–2005 with the construction of maps in ArcMap program. 相似文献
20.
The spatial and temporal structure of the effects of solar activity (SA) and galactic cosmic ray (GCR) flux variations on the lower atmosphere circulation has been studied based on NCEP/NCAR reanalysis archive for 1948–2006 and MSLP (Climatic Research Unit, UK) data for 1873–2000. It has been shown that the GCR effects on pressure variations are characterized by a strong latitudinal and regional dependence, which is determined by specific features of the tropospheric circulation in the studied regions. The distribution of the correlation coefficients for mean yearly values of atmospheric pressure with the GCR flux intensity is closely related to the position of the main climatological fronts. The periodic (∼60 years) changes in the correlation sign of the pressure at high and middle latitudes with Wolf numbers have been revealed. It has been suggested that the changes of the sign of SA/GCR effects on atmospheric pressure are caused by the changes of the macrocirculation epochs, which, in turn, may be related to large-scale processes on the Sun. 相似文献