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1.
A comparison covering more than three decades is made between the seasonal variation of radar meteor influx and seasonal variations in the occurrence probabilities of ionosonde sporadic-E parametersƒ0Es and ƒbEs for different diurnal intervals at two Southern Hemisphere stations. The analyses show that for medium intensity 3Em type sporadic-E no clear correlation with major Southern Hemisphere meteor shower activity exists. This finding which does not support some earlier shorter period surveys suggests the need for further work into the aeronomy of Es source ions.  相似文献   

2.
Evidence is presented to suggest that the ƒ0Es value tends to be high at positions in the Es-layer where trough slope-lines and crest slope-lines of F2-layer irregularities meet the Es-layer. These slope-lines are drawn through the troughs and crests, respectively, of the characteristic kinks in the F2-layer ionization contours, which are associated with F2-layer irregularities.

A rotating-loop direction-finding system has allowed an estimation of the distribution of ionization, which gives rise to Sporadic-E echoes. Analysis of Sporadic-E occurrence, on two occasions, suggests that the reflecting surfaces are frontal in nature, the fronts having a separation from each other of some tens of kilometres, and probably existing as closed curves, with diameters of the order of several hundreds of kilometres. A possible association between these structures and the occurrence of the green line of the airglow, is discussed.

A distribution of ionization, which will give contours showing “clouds” of ionization at some frequencies and a ripple structure at other frequencies, is proposed, in an endeavour to explain the apparent dual nature of Sporadic-E occurrence.

The evidence seems to indicate that the mechanism operating at the Es-layer level, producing the phenomenon of Sporadic-E, is the same as that which produces the F2-layer irregularities which are responsible for “Spread-F”.  相似文献   


3.
The effects of E-region electric fields on F-region parameters like height of constant electron density contours (hN) and semi-thickness, at an equatorial station, Trivandrum, are investigated. The E-region east-west electric field (Ey) has been deduced using the horizontal magnetic field values from the ground magnetograms. It is found that the semi-thickness parameter and hN follow closely the E-region electric field (Ey) variations in the forenoon and noon periods. In the afternoon, it is shown that there is close association between hN and Ey, when the electric field variations are large. On a day-to-day basis also, hN and the E-region electric field show very good correlation in the forenoon and noon hours. It is also shown that higher levels are affected more than the lower levels in the F-region by Ey.  相似文献   

4.
During the first international joint observation of the Leo strong meteor shower, multidisciplinary and multi-media synthetic observation of Leo and Draco strong meteor showers and their catastrophic space weather events were carried out. The comprehensive analysis of the observed and related data of the Leo, Perseus and Draco strong meteor showers obtained for near half a century (from 1957 to 2003) fully verifies that the non-sporadic periodic strong meteor shower may lead to catastrophic space weather events. Preliminary identification is made of the following: the mechanism of formation of strong meteor showers, the law of occurrence of the fbEs abnormal peak and serious safety hazards for astronavigation. Also discussed in this paper are the evolutionary process of cometary dust, the law of occurrence and loss of cosmic dust storm and the mechanism of maintaining cosmic dust in the mid-latitude Es layer.  相似文献   

5.
High resolution E-region measurements carried out on 16 November 1983 using the EISCAT incoherent scatter radar are presented. The experiment was monostatic with a vertical radar beam, and it was based on a Barker-coded four-pulse code on one frequency channel and Barker-coded single pulses on three channels. The basic integration time was 15 s and the spatial resolution 450 m. The results reveal a short-lived but intense thin sporadic E-layer at 18:00–18:06 U.T. at an altitude of about 106 km. Both before and during the event, downward ion velocities of the order of 100 m s−1 are observed above this height. A convergent null in the vertical ion speed is occasionally seen at the layer altitude. The layer occurrence is associated with auroral arcs drifting across the radar beam. Simultaneous observations of the STARE radar show an ionospheric electric field of 25–30 mV m−1. The field always has a westward component, which is in accordance with the observed downward plasma flow. Most of the time when the layer is intense, the field points into the NW-sector. Theoretically, this field direction should create convergent vertical plasma motion. Therefore it is suggested that the observed Es-layer is created by the action of the auroral electric field rather than by the wind shear mechanism.  相似文献   

6.
Quasitrapped (Hmin < 100 km) protons with energies E > 440 keV have been detected during magnetic storms by the IK-5 satellite in a narrow zone with a center at L = 3.0−3.2; this zone is well separated from the region of Isotropie fluxes at L > 4. Data for five moderate storms have been analysed in detail. It was found that the quasitrapped proton peaks appear during the recovery phase of magnetic storms and that the scattering of protons toward low mirror points takes place in all local time sectors. The relation between the observed precipitation of the E > 440 keV protons and the intraplasmaspheric precipitation of low-energy protons has been discussed in the light of the theory of generation of ion-cyclotron waves by the ring current and the theory of parasitic interaction of these waves with the radiation belt protons. A series of arguments indicates that the phenomenon under study is connected with the magnetopheric process which generates the SAR arcs.  相似文献   

7.
The method of identifying absorption line systems in QSO spectra (Cui et al. 1983; Chen et al. 1983) is further developed here. Certain limitations of the method and their improvements are discussed. Certain other problems requiring further study are pointed out. The improved method is applied to PKS 0528-250, and gives two new absorption line systems Za = 0.065 and 0.0345 in addition to the four systems Za = 2.8110, 2.8130, 2.5275, 2.1410, consistent with the systems A1A2, B, C of Norton et al. (1980). However, the systems D1, D2, E, F and G of Chen and Norton (1984) are not recovered. The reason for this discrepancy is discussed.  相似文献   

8.
A double-probe electric field detector and two spatially separated fixed-bias Langmuir probes were flown on a Taurus-Tomahawk sounding rocket launched from Poker Flat Research Range in March 1982. Interesting wave data have been obtained from about 10s of the downleg portion of the flight during which the rocket passed through the auroral electrojet. Here the electric field receiver and both density fluctuation (δn/n) receivers responded to a broad band of turbulence centered at 105 km altitude and at frequencies generally below 4 kHz. Closer examination of the two (δn/n) turbulent waveforms reveals that they are correlated, and from the phase difference between the two signals, the phase velocity of the waves in the rocket reference frame is inferred. The magnitude and direction of the observed phase velocity are consistent either with waves which travel at the ion sound speed (Cs) or with waves which travel at the electron drift velocity. The observed phase velocity varies by about 50% over a 5 km altitude range—an effect which probably results from shear in the zonal neutral wind, although unfortunately no simultaneous neutral wind measurements exist to confirm this.  相似文献   

9.
Small-scale spatially periodic distortions of auroral forms have been studied utilizing low-light level television observations made at various locations in the Northern and Southern Hemispheres. The most commonly observed features were folds and vortex-like curl formations. The curls, identified here with the Kelvin-Helmholtz instability due to fluid shear, invariably had a counterclockwise rotational shape and motion when viewed in a direction anti-parallel to the Earth's magnetic field. The typical measured wavelength (5 km) and measured growth rate (4.2 sec−1) were used to evaluate the Kelvin-Helmholtz dispersion relation for the apparent shear ωs = ∂ νx/ ∂y (28 sec−1). The apparent horizontal velocities of both folds (0–5 km/sec) and curls (0–22 km/sec) were invariably observed to be counterclockwise with respect to the multiple arc centre when viewed antiparallel to B. Consistent agreement between rotational shape and rotational motion suggests that the apparent growth rate and the apparent horizontal velocities closely approximate the actual values. If the shear results from E×B drifts in a space charge field, the calculated value for ωs, implies an unneutralized electron density 0–1 cm−3 and a ΔE across the arc element 500mV/m. The velocity measurements indicate that the ΔE values for individual elements can combine to produce transient electric fields at the edges of multiple arcs as high as 1000 mV/m.  相似文献   

10.
The evolution of the cosmic ray primary composition in the energy range 106–107 GeV (i.e. the “knee” region) is studied by means of the e.m. and muon data of the Extensive Air Shower EAS-TOP array (Campo Imperatore, National Gran Sasso Laboratories). The measurement is performed through: (a) the correlated muon number (Nμ) and shower size (Ne) spectra, and (b) the evolution of the average muon numbers and their distributions as a function of the shower size. From analysis (a) the dominance of helium primaries at the knee, and therefore the possibility that the knee itself is due to a break in their energy spectrum (at EkHe=(3.5±0.3)×106 GeV) are deduced. Concerning analysis (b), the measurement accuracies allow the classification in terms of three mass groups: light (p,He), intermediate (CNO), and heavy (Fe). At primary energies E0≈106 GeV the results are consistent with the extrapolations of the data from direct experiments. In the knee region the obtained evolution of the energy spectra leads to: (i) an average steep spectrum of the light mass group (γp,He>3.1), (ii) a spectrum of the intermediate mass group harder than the one of the light component (γCNO2.75, possibly bending at EkCNO≈(6–7)×106 GeV), (iii) a constant slope for the spectrum of the heavy primaries (γFe2.3–2.7) consistent with the direct measurements. In the investigated energy range, the average primary mass increases from lnA=1.6–1.9 at E01.5×106 GeV to lnA=2.8–3.1 at E01.5×107 GeV. The result supports the standard acceleration and propagation models of galactic cosmic rays that predict rigidity dependent cut-offs for the primary spectra of the different nuclei. The uncertainties connected to the hadronic interaction model (QGSJET in CORSIKA) used for the interpretation are discussed.  相似文献   

11.
Auroral luminosities of the main emission lines in the aurora have been calculated for excitation by an isotopic primary electron flux with spectra of the form J(E) = AE exp (−E/E1) + B(E2)E exp (−E/E1). The variation of emissions from O and N2+ with height are shown, as are the variations of column integrated intensities and pertinent intensity ratios with the characteristic energy E2, this leading to a method of estimating the electron spectrum from ground observation.  相似文献   

12.
The dependence of geomagnetic activity during a recurrent magnetic storm on the solar-wind magnetic field and plasma parameters has been studied. According to variations of solar-wind magnetic field strength B, a recurrent magnetic storm is divided into two stages: the first proceeding during the peak of B, and the second proceeding after the return of B to quiet level. The Kp index vs solar-wind parameters scattering diagrams for stages I and II differ significantly. In particular, the random scattering for stage I is much larger than for stage II. It was found that for stage I the Kp index correlates with B, with the sign and value of northsouth field component Bz and with the magnitude ΔB of field fluctuations, the situation being similar to that during sporadic magnetic storms, though the scale of the event is smaller. For stage II, the Kp index does not correlate with B, but strongly correlates with ΔB and weaker—with Bz. So geomagnetic activity at stage II is supported mainly by solar-wind magnetic field fluctuations. The dependence of the Kp index on plasma parameters (concentration of protons n, bulk velocity v and temperature T) is weak for both stages.  相似文献   

13.
We derive strong constraints on the Yukawa couplings and the vacuum expectation value in the singlet majoron model. The presence of a small gravitationally induced mass for the majoron can be used to set a constraint on its vacuum expectation value. If the singlet symmetry breaking scale is larger than the electroweak symmetry breaking scale, lepton number violating interactions in equilibrium with electroweak sphaleron interactions would destroy any prior baryon asymmetry. If the baryon asymmetry is not generated at the electroweak scale or later, strong bounds on the Yukawa couplings h 10−7 and VEVs vs < vEW are derived. We also carefully rederive baryogenesis bounds on neutrino masses, finding that in general they apply not to the masses themselves, but only to related parameters, and they are numerically somewhat less stringent than has previously been claimed.  相似文献   

14.
Charged boson stars and vacuum instabilities   总被引：1，自引：0，他引：1  
We consider charged boson stars and study their effect on the structure of the vacuum. For very compact particle like “stars”, with constituent mass m* close to the Planck mass mPl, i.e. m2* = O(m2Pl), we argue that there is electric charge Zc, which, primarily, is due to the formation of a pion condensate (Zc 0.5−1e, where is the fine structure constant and e is the electric charge of the positron). If the charge of the “star” is larger than Zc we find numerical evidence for a complete screening indicating a limiting charge for a very compact object. There is also a less efficient competing charge screening mechanism due to spontaneous electron-positron pair creation in which case Zc −1e. Astrophysical and cosmological abundances of charged compact boson stars are briefly discussed in terms of dark matter.  相似文献   

15.
By means of a simple relation between the velocity v of the fluid particle and the velocity vf of the photospheric footpoint of the magnetic field line vz and Bz being respectively the components of v and the magnetic field B normal to the photospheric surface, it is shown formally that through the phtospheric surface the transport of all the quantities attributed to the magnetic field, such as the magnetic flux, the magnetic energy and the helicity, is independent of vz, and vf is the only kinematical quantity on which the transport depends. In addition, in the neighborhood of the neutral line the velocity vl of the moving curve of constant Bz is found to be equal approximately to the component of v or vf in the direction of vl. Since vl can be measured or extimated, so can the components of v and vf near the neutral line.  相似文献   

16.
Using a complete non-local convection theory, we carried out the theoretical calculations of 7Li depletion of the solar convective envelope models with different convective parameters c1 and c2, and got a model of the solar convection zone consistent with the observed 7Li abundance and the depth of the solar convection zone determined by helioseismic techniques. The overshooting distance of effective non-local convective mixing of 7Li is very extensive, which is about 1.07HP or 0.09R. However, the super-radiative temperature zone is much narrower, and it is only 0.20HP or 0.016R.  相似文献   

17.
A numerical analysis of cyclotron instabilities is carried out by computing the dispersion relation for a three component cold plasma-beam system. Rates of growth and damping for various values of the stream density are calculated from the dispersion relation. The rates of growth and damping increase monotonically as the number density of the proton stream increases. It is found that the frequencies at the rates of maximum growth and the damping decrease slightly to lower frequencies and a sharp peak at these frequencies becomes blunt. The minimum e-folding times of an ion cyclotron wave for (a) σs = 10−4, σi = 10−2 and (b) σs = 10−1, σi = 10−2 are about 3·84 and 0·16 sec respectively in the vicinity of the equatorial plane at 6 Re, where σs and σi are the ratios of the beam density Ns and the helium ion (H6+) density Ni to the total positive ions in the plasma-beam system.  相似文献   

18.
Unusually great fluctuations in the ΔB module of the geomagnetic field have been observed in the polar cap from the satellite Cosmos-321. They are explained by small-scale two-sheet field-aligned current systems which exist during the periods when magnetic fields having a considerable northward Bz(Bz 10 nT) component are observed in interplanetary space.  相似文献   

19.
The empirical model of disturbed magnetosphere of Tsyganenko and Usmanov (1982) and the semi-empirical model of the storm-time magnetospheric configuration of Tsyganenko (1981) are used to find the critical energy for non-adiabatic particle scattering in the midnight sector. Computed values of Ecrit vs L are compared with the appropriate experimental data of Imhof et al. (1977). It is found that none of the considered models is able to reproduce the observed steep decrease of Ecrit with L. The steepest slope is given by the Tsyganenko model which includes a current sheet with the finite thickness. The current sheet thickness is a crucial parameter in the non-adiabatic scattering problem. In discussion we point to natural limitations of an empirical model as far as the current sheet thickness is to be determined. Imhof et al.'s data as well as some magnetic field data sets seem to indicate that magnetosphere models incorporating a thin current sheet and allowing for the thickness dependence on the geocentric distance would probably be closer to reality than the considered models, at least during higher levels of magnetic activity.  相似文献   

20.
Voyager 1, exiting the earth's magnetosphere along the dawn meridian at a velocity of ~11 km/sec, measured strong tailward flows of ions (E30keV) immediately outside the magnetopause. These flows are found to originate sunward of the dawn meridian and to exhibit significant variabilities on the time scale of 400 msec. The variations are not related to changes in the magnetosheath magnetic fields and are likely produced up-stream by the leakage of magnetosphere protons or by a magnetopause particle energization process. The intensities of the dawn meridian ion flows are greater in the magnetosheath than in the magnetosphere. The flows appear to penetrate inside the dawn magnetosphere to a depth 0.1 R>E, less than an ion gyroradius.  相似文献   

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