共查询到20条相似文献，搜索用时 31 毫秒
1.
The power spectra of time variations in the electric field strength in the near-Earth’s atmosphere and in the geomagnetic field horizontal component, which were simultaneously observed at the Paratunka observatory (φ = 52°58.3′ N; λ = 158°14.9′ E) in September 1999, have been studied. The periods of the day (including sunrise, sunset, and night) have been considered. It has been indicated that oscillations with periods T ～ 2.0–2.5 h are present in the power spectra of these parameters during the day. The intensity of these oscillations increases noticeably and the oscillations in the band of periods T < 1 h increase simultaneously in the field strength power spectra at sunrise. The variations in the argument of the cross-spectrum of these parameters indicated that oscillations in the 2.0–2.5 h period band are caused by sources that are located above the ionospheric dynamo region; at the same time, oscillations in the 0.5–1 h period band are caused by sources in the lower atmosphere. A possible mechanism by which these oscillations are generated, related to the vortex motion of convective cells that originate at sunrise in the boundary atmospheric layer, is proposed. 相似文献
2.
G. M. Shved N. V. Karpova P. P. Ammosov G. A. Gavrilyeva V. I. Perminov A. I. Semenov 《Geomagnetism and Aeronomy》2009,49(3):381-383
Atmospheric temperature oscillations at similar frequencies have been detected in the spectra of variations in the rotational temperatures of the OH and O2 nighttime emissions, simultaneously observed at two spaced stations in the range of periods ～1–3 h. These oscillations are probably caused by global waves: short-period solar tides and/or free oscillations of the atmosphere. 相似文献
3.
D. Altadill 《Annales Geophysicae》1996,14(7):716-724
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
4.
Based on the published analysis of the average monthly variations in solar activity and temperature of the upper atmosphere in the region of the mesopause and lower thermosphere (after elimination of the average long-term variations during different 11-year cycles), it was indicated that the periods and amplitudes of the observed quasibiennial variations monotonically decrease in the course of time. The regularity of these variations is described by the Airy function, which represents a wave train with decreasing amplitude and period and reflects cyclic hydrodynamic processes in the Sun’s interior. A spectral analysis of the quasibiennial variations modelly described by the Airy function has been performed. It has been revealed that the period amplitudes near the average value for 2.25 years (27 months) are distributed normally with a dispersion of ～0.5 years. According to several publications, similar periods are obtained by analyzing measurements of long-term variations in solar activity and parameters of the lower and middle atmosphere. This indicates that the values of the periods are obtained randomly. Therefore, a standard Fourier analysis does not make it possible to determine a real character of the quasibiennial variations since a real physical process is not revealed in the course of this analysis. 相似文献
5.
Three- to six-day oscillations in the mesopause temperature have been observed all over the year. While these oscillations can be explained by planetary wave activity in wintertime, their summertime appearance is still under discussion.One effect possibly contributing to such summertime oscillations in the mesopause is acoustic heating. Infrasound generated by low-pressure areas or thunderstorm cells propagates into the upper atmosphere and deposits heat in this region. It is speculated that the oftentimes about weekly variation of low-pressure areas due to troposphere planetary wave activity is a potential source mechanism for mesopause temperature oscillations through infrasound as a transporting mechanism.The modeling structure of infrasound propagation as well as of acoustic heating is presented. It leads to the quantification of expected temperature fluctuations and acoustic heating rates at the mesopause height, which both appear to be too small to give a sole explanation for the 3–6-day oscillation. 相似文献
6.
G. A. Mikhailova Yu. M. Mikhailov O. V. Kapustina G. I. Druzhin S. E. Smirnov 《Geomagnetism and Aeronomy》2008,48(2):251-259
A spectral analysis of simultaneous diurnal variations in the E z component of the quasi-static electric field in the near-Earth atmosphere, VLF radio noise, and the horizontal component of the geomagnetic field, observed at Kamchatka in September 1999, has been performed. These geophysical parameters are indirectly used to study wave processes in the near-Earth atmosphere and in the ionospheric D and dynamo regions within the band of periods of internal gravity waves (T = 0.5?3.5 h). The correlation method in the frequency region is used to analyze the interrelation between the wave processes in these atmospheric regions. The power cross-spectra of various pairs of geophysical parameters have been studied depending on meteorological, seismic, and geomagnetic activities. It is shown that the oscillations in the power spectra in the T ～ 1–1.5 h band of periods are caused by the sources of internal gravity waves in the near-Earth atmosphere and by the remote sources above the dynamo region of the ionosphere within the T ～ 1.5–3 h band of periods. 相似文献
7.
The empirical model of variations in the emitting layer height and parameters has been developed based on an analysis of the rocket measurements of the vertical distributions in the 630 nm intensity. The dependences on the solar zenith angle during a day are most substantial. This dependence is responsible for the character of seasonal variations at different latitudes. The height of the emitting layer increases with increasing solar activity, reflecting a temperature rise in the upper atmosphere. The negative trend—0.35 km yr?1 in the interval 1964–1990—has been revealed. 相似文献
8.
S. I. Musatenko Yu. S. Musatenko E. V. Kurochka A. V. Lastochkin V. Ya. Cholij O. I. Maksimenko A. S. Slipchenko 《Geomagnetism and Aeronomy》2006,46(2):173-182
The emission (or modulation) line, which manifests itself during high-speed (the speed of entry into the atmosphere is about 70 km/s) meteor showers (Perseids, Orionids, Leonids), has been detected in the fluctuation spectra of ionospheric plasma radio noise at λ = 2 m. The line frequency varies from 12 to 60 Hz depending on activity of ionospheric ionization sources and local characteristics of a meteor shower, time of day, etc. The line has a width of 2–3 Hz and can have satellites. The dusty plasma characteristics have been estimated on the assumption that ionospheric noise is modulated or emitted due to dusty plasma oscillations. 相似文献
9.
V.V. Surkov Y. Matsudo M. Hayakawa S.V. Goncharov 《Journal of Atmospheric and Solar》2010,72(5-6):448-456
Spectrograms and ELF power spectra of magnetic variations originated from sprite-producing lightning discharges have been analyzed to extract both parent lightning and sprite parameters. Some of the spectrograms and power spectra have been found to have approximately quasi-oscillatory shape in the frequency range 0–40 Hz with maximum repetition period about 15–20 Hz. A theory predicts that this interesting peculiarity of the power spectra can be due to interference between electromagnetic fields originated from the parent lightning discharge and from the sprite. A smooth envelope of the power spectrum was shown to have a form of damped oscillations with period close to reciprocal value of sprite lag time. A technique of extracting sprite parameters based on the sprite-producing lightning power spectrum is proposed. The lack of the first Schumann resonance and other features occasionally observed in spectral resonance structure were also discussed. 相似文献
10.
Records of the coastal mareographs during the December 26, 2004, tsunami are used to study the fine structure of the tsunami wave power spectra. It is shown that a series of maxima is observed in their spectra near the source in a range of internal gravity wave frequencies of 0.2–1.2 mHz, which coincides with the frequencies of the natural oscillations of the Earth. This experimental finding enables us to propose a possible physical mechanism for the formation of tsunami waves as a result of oscillations in the sea bottom at these frequencies. Internal gravity waves in the Earth’s atmosphere excited in this way are found in the variations of the total electron content that resulted from this powerful earthquake. 相似文献
11.
The results of rocket and satellite measurements available in the literature of 5.3-μm nitric oxide emission in the upper atmosphere have been systematized and analyzed. Analytical dependences describing the height distribution of volumetric intensity of 5.3-μm emission of the NO molecule and its variations in a range of heights from 100 to 130 km as a function of the time of year, day, latitude, and solar activity have been obtained. 相似文献
12.
K. Mohanakumar 《Annales Geophysicae》1994,12(5):448-456
A study on the variability of temperature in the tropical middle atmosphere over Thumba (8 32’ N, 76 52’ E), located at the southern part of India, has been carried out based on rocket observations for a period of 20 years, extending from 1970 to 1990. The rocketsonde-derived mean temperatures over Thumba are corrected prior to 1978 and then compared with the middle atmospheric reference model developed from satellite observations and Solar Mesosphere Explorer (SME) satellite data. Temperature variability at every 1 km interval in the 25–75 km region was analysed. The tropical stratosphere is found to be highly stable, whereas considerable variability is noted in the middle mesosphere. The effect of seasonal cycle is least in the lower stratosphere. Annual and semi-annual oscillations in temperature are the primary oscillations in the tropical middle atmosphere. Annual temperature oscillations are dominant in the mesosphere and semi-annual oscillations are strong in the stratosphere. The stratopause region is noted to be the part of the middle atmosphere least sensitive to the changes in solar activity and long-term variability. 相似文献
13.
V. P. Antonova K. E. Dungenbaeva A. V. Zalizovskii A. S. Inchin S. V. Kryukov V. M. Somsikov Yu. M. Yampol’skii 《Geomagnetism and Aeronomy》2006,46(1):101-109
The singularities of the wave disturbance spectra of the nonequilibrium atmosphere in the range of acoustic gravity waves (AGWs) have been analyzed. Using the dispersion ratio for AGWs in the nonequilibrium atmosphere, it has been established that the spectra in the daytime and nighttime hours are different and this difference, caused by a nonequilibrium spectrum sensitivity to atmospheric temperature, can reach several percent in certain atmospheric regions. For the spectrum of the equilibrium model of the atmosphere, the difference between the daytime and nighttime spectra makes up several fractions of percent. As a result of the spectral treatment of variations in pressure and intensity of cosmic rays (CRs), it has been found out that the daytime AGW spectrum is higher-frequency than the nighttime spectrum. A comparison of the theoretical calculations of the AGW spectrum with observations has made it possible to distinguish the effect of nonequilibrium in the AGW spectral composition. 相似文献
14.
Yu. V. Balabin A. V. Germanenko B. B. Gvozdevsky E. V. Vashenyuk 《Geomagnetism and Aeronomy》2014,54(3):347-356
X-ray intensity variations in the surface layer of the atmosphere during precipitation in Apatity and Spitsbergen were analyzed. Based on a comprehensive system of monitoring over the radiation background, X-ray radiation variations were detected. These variations were found to be associated with meteorological processes in the lower atmosphere. X-ray energy spectra were obtained under good weather and precipitation conditions. These spectra have no characteristic lines inherent to radionuclides. Additional studies make it possible to suggest that the growth in X-ray radiation during precipitation is mainly caused by braking radiation of energetic electrons additionally accelerated by electric fields in rain clouds. 相似文献
15.
A spectral analysis of the diurnal variations in the geomagnetic field horizontal component, observed at Kamchatka and Barrow polar observatory in September–October 1999, has been performed. The complete set of oscillations of thermal tidal atmospheric waves with T = 24, 12, 8, and 4 h has been detected in the variation spectral power (Sq) at Kamchatka, and only the fundamental harmonic with T = 24 h has been distinguished at Barrow. The above periods vary in both directions relative to stable maximums during strong geomagnetic disturbances. The relative spectral intensity at subharmonics also vary toward the fundamental harmonic with a period of 24 h. In the frequency band 0.5–3 h (IGW periods), the maximal intensity in the background spectra is observed at T ～ 2 h and increases by an order of magnitude with increasing geomagnetic activity at both Kamchatka and Barrow. A day before earthquakes, the intensity of this maximum is below the rms background values, and the spectra widen toward the region of periods shorter than 2 h. A similar effect was previously observed in the power spectra of the diurnal variations in the quasistatic electric field and VLF noise, simultaneously measured in September–October 1999. 相似文献
16.
《Journal of Atmospheric and Solar》2002,64(8-11):1229-1240
Continuous wind observations allow detailed investigations of the upper mesosphere circulation in winter and its coupling with the lower atmosphere. During winter the mesospheric/lower thermospheric wind field is characterized by a strong variability. Causes of this behaviour are planetary wave activity and related stratospheric warming events. Reversals of the dominating eastward directed mean zonal winds in winter to summerly westward directed winds are often observed in connection with stratospheric warmings. In particular, the amplitude and duration of these wind reversals are closely related to disturbances of the dynamical regime of the upper stratosphere.The occurrence of long-period wind oscillations and wind reversals in the mesosphere and lower thermosphere in relation to planetary wave activity and circulation disturbances in the stratosphere has been studied for 12 winters covering the years 1989–2000 on the basis of MF radar wind observations at Juliusruh (55°N, since 1989) and Andenes (69°N, since 1998). Mesospheric wind oscillations with long-periods between 10 and 18 days are observed during the presence of enhanced planetary wave activity in the stratosphere and are combined with a reversal of the meridional temperature gradient of the stratosphere or with upper stratospheric warmings. 相似文献
17.
S. I. Boldyrev O. P. Kolomytsev G. S. Ivanov-Kholodny A. P. Ignatyev 《Geomagnetism and Aeronomy》2009,49(8):1278-1282
The present-day models of the Earth’s upper atmosphere make it possible to construct the spatial-temporal pattern of variations
in the atmospheric parameters on the planetary scale in essence in the averaged form. The set of data on the satellite deceleration
in the atmosphere, probe measurements aboard geophysical rockets, and radiowave incoherent scatter measurements in the Earth’s
atmosphere are used to construct these standard models. The current level of the space studies makes it possible to use a
new method to study the Earth’s upper atmosphere: to study the upper atmosphere by measuring the absorption of the solar XUV
radiation by the Earth’s atmosphere during the solar disk observations. 相似文献
18.
Summary Attention is paid to the effect of light pressure, completely ignored in the present explanations on the energetics of dynamical processes in atmosphere. It seems even to be of great importance and play a great role, especially in the upper atmosphere. It seems there are three phenomena produced probably by this process: 1) Appearing of the earth atmosphere tide on the night side. 2) Presence of strong west winds on the great altitude. 3) Vertical oscillations of the upper atmosphere density. 相似文献
19.
The response of the thermobaric characteristics of the high-latitude troposphere to short-term events attributed to solar
activity (solar cosmic rays and geomagnetic storms) has been investigated. The spatial manifestation of these disturbances
in the troposphere is shown to be of a “focal” character. It is found that the manifestation is most evident in the cold period
and depends on the properties of the underlying surface (land, ocean). The properties of the variations of the troposphere
air temperature in the manifestation “foci” on the standard isobaric surfaces, as well as the variations of the altitude profile
of temperature and the long-wave radiation flux at the upper boundary of the atmosphere, have been considered. The variations
of the heat content of the high-latitude troposphere after solar flares have been analyzed. The variation of the thermobaric
field is shown to be accompanied by the rearrangement of circulation forms in moderate and polar latitudes. The revealed properties
are completely explained within the mechanism proposed here for the solar activity effect on the climatic characteristics
of the troposphere. 相似文献
20.
The existence and development of the quasi-2-day oscillations in the plasma frequency variations of the F region at northern middle latitudes are investigated. A new approach to study the quasi-2-day oscillations is presented, using a methodology that allows us to do such a study at fixed heights. The hourly values of plasma frequency at fixed heights, from 170 km to 220 km at 10 km step, obtained at the Observatori de lEbre station (40.8°N, 0.5°E) during 1995 are used for analysis. It is found that quasi-2-day oscillations exist and persisted in the ionospheric plasma frequency variations over the entire year 1995 for all altitudes investigated. The dominant period of oscillation ranges from 42 to 56 h. The amplitude of oscillation is from 0.1 MHz to 1 MHz. The activity of the quasi-2-day oscillation is better expressed during the summer half year when several enhancements, about 15–30 days in duration, were observed. The largest enhancements of the oscillation occurred during early June, July and early August; i. e., near and after the summer solstice when the 2-day wave in the middle neutral atmosphere typically displays its largest activity in the Northern Hemisphere. The results obtained may help us understand better the possible influencing mechanisms between the 2-day wave in the middle neutral atmosphere and the ionospheric quasi-2-day oscillations. 相似文献