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1.
Geomagnetism and Aeronomy - Additional horizontal traces of ground reflections were observed in a studied series of high-latitude, Kp sounding ionograms from the Interkosmos-19 satellite. The... 相似文献
2.
Geomagnetism and Aeronomy - An empirical model of the equatorial anomaly in the critical frequency foF2 of the ionospheric F2 layer is constructed. The model is based on Interkosmos-19 satellite... 相似文献
3.
Quasi-wave disturbances in the topside daytime ionosphere, related to auroral activity, have been detected using the data of radiosounding onboard the Intercosmos-19 satellite on April 28, 1979. A disturbance was caused by an abrupt enhancement of the eastward electrojet, which was not reflected in the variations in the AE and AU indices. According to the estimates, the period of electron density disturbances was about 0.5 h, the velocity was 350 m/s, and the length along the meridian was several hundreds of kilometers, which corresponds to medium-scale traveling ionospheric disturbances (TIDs). The disturbance amplitude was only 30 km in the hmF2 variations and 0.20–0.25 MHz in the foF2 variations but increased to 0.25–0.30 MHz in the plasma frequency variations at satellite altitudes of 520–580 km with increasing altitude. It is impossible to register so weak short-period variations during ground-based sounding. The method for detecting disturbance spatial characteristics has been proposed. The disturbance spectrum including three quasiperiodic structures has been revealed using this method. The optimal estimates have been made for the trend, described by the polynomial of the third degree, and for the expansion of the residuals in terms of three harmonics. 相似文献
4.
Complex ionograms from the Intercosmos-19 satellite with strongly delayed and sometimes multiple reflections from the Earth are considered. An analysis shows that these reflections are usually associated with sharp horizontal gradients of the ionospheric plasma. Such gradients are formed on the walls of the main ionospheric trough, at peaks of electron density, and on the inner and, especially frequently, on the outer slope of the crest of the equatorial anomaly. In one case, distant reflections from the Earth (DREs) formed near the equator, when the satellite in perigee was lower than the F2-layer maximum height. A quantitative interpretation of the most typical cases of DREs is given based on ray tracing. For this purpose, the model of the ionosphere under the satellite is developed, ray paths are calculated, and model ionograms are formed. The good agreement between experimental and model ionograms allows us to conclude that the task of interpreting complicated ionograms obtained by Intercosmos-19 with DRE has been solved successfully. 相似文献
5.
Geomagnetism and Aeronomy - The principles and algorithm for the construction of an empirical model of the ionospheric trough for quiet (Kр = 2) daytime (06−18 LT) winter conditions in... 相似文献
6.
N. I. Izhovkina A. T. Karpachev I. S. Prutensky S. A. Pulinets Z. Klos H. Rotkel 《Geomagnetism and Aeronomy》2009,49(8):1254-1256
It has been indicated that the spectrum of electrostatic waves in the ionospheric plasma depends on the geophysical conditions
and solar wind parameters. The wave field measurements in the frequency band 0.1–10 MHz in the topside ionosphere were used
to analyze the electrostatic instabilities of the plasma electron content (the APEX satellite experiment). A change of the
sign of one magnetic field component at the geomagnetic equator can result in the formation of the large-scale irregular plasma
structure with a decay of the natural electrostatic oscillations and vortices in unstable plasma. The plasma particle polarization
drift from the region of decay of electrostatic oscillations and vortices can cause large plasma density and temperature gradients
across the geomagnetic field. New vortices can originate at these gradients. This mechanism of plasma vortex formation and
decay can be important for mass and energy convection in the topside ionosphere. 相似文献
7.
A.T. Karpachev G.F. Deminova N. Beloff T.D. Carozzi P.F. Denisenko M. Lester T. Karhunen 《Journal of Atmospheric and Solar》2011,73(5-6):567-577
We used bottomside ground observations and topside sounding data from the Intercosmos-19 satellite to study a Travelling Ionospheric Disturbance (TID) that occurred in response to Large-Scale Internal Gravity Wave (LSIGW) propagation during a substorm on November 30, 1979. We built a global scheme for the wavelike ionospheric variations during this medium substorm (AEmax ～800 nT). The area where the TID was observed looks like a wedge since it covers the nighttime hours at subauroral latitudes but contracts to a ～02 h local sector at low latitudes. The ionospheric response is strongly asymmetric because the wedge area and the TID amplitude are larger in the winter hemisphere than in the summer hemisphere. Clear evidence was obtained indicating that the more powerful TID from the Northern (winter) hemisphere propagated across the equator into the low latitude Southern (summer) hemisphere. Intercosmos-19 observations show that the disturbance covers the entire thickness of the topside ionosphere, from hmF2 up to at least the 1000 km satellite altitude at post-midnight local times. F-layer lifting reached ～200 km, Ne increases in the topside ionosphere by up to a factor of ～1.9 and variations in NmF2 of both signs were observed. Assumptions are made concerning the reason for the IGW effect at high altitudes in the topside ionosphere. The relationship between TID parameters and source characteristics determined from a global network of magnetometers are studied. The role of the dayside cusp in the generation of the TID in the daytime ionosphere is discussed. The magnetospheric electric field effects are distinguished from IGW effects. 相似文献
8.
The profiles of the plasma density in the topside ionosphere, according to the data of sounding on board the Intercosmos-19 satellite, are presented. It is shown that the large-scale fluctuations of the plasma density can be related to the propagation and attenuation of the atmospheric waves (e.g., acoustic gravity waves) in the dynamo region of the ionosphere. In the topside ionosphere, suprathermal particle fluxes can be formed and the plasma density can be modulated at an attenuation of small-scale electrostatic fluctuations of the plasma electron component in plasma pits. Plasma vortices can be formed when polarization fluxes of charged particles escape from regions of heating. The vortex field imparts stability to the inhomogeneous plasma structure, necessary for experimental detection of this structure. 相似文献
9.
Complicated ionograms of topside sounding on board the Intercosmos-19 satellite, which were registered on November 26, 1980,
in the dusk sector (1800 LT) at the latitudes of the equatorward wall (55°–62° ILAT) of the main ionospheric trough (MIT),
are analyzed. They are characterized by the presence of two extra traces at distances larger than the main traces. Approaching
the MIT minimum, all traces become more scattered, converge, and join into one strongly diffusive trace. An attempt of interpretation
of the complicated ionograms on the basis of trajectory calculations performed by the method of characteristics in the “complex”
two-dimensional version (in two mutually intersecting planes) is undertaken. The modeling shows that the extra traces could
be related to the presence of a large-scale irregularity stretched along the geomagnetic meridian at the equatorward wall
of the MIT. The calculations make it possible to estimate the parameters of the irregularity: the intensity is δfoF2 ∼ 30%, the length is several hundred kilometers, the semi-thickness is 50–60 km, and the height is 350 km. The possible
formation causes of the irregularity are discussed. The intensification of the diffuseness of all traces is related to the
increase in the intensity of small-scale irregularities, which is usually observed when approaching the MIT minimum. 相似文献
10.
Geomagnetism and Aeronomy - Changes in the structure of the summer equatorial anomaly of electron density with local time and longitude at high solar activity are considered in detail according to... 相似文献