共查询到20条相似文献，搜索用时 390 毫秒
1.
Long-period (more than 20 min) quasi-periodic pulsations (QPP) occurring in the Earth's magnetic field (EMF) before the proton flare are studied by the method of spectral correlation analysis of geomagnetic field H-component. The corresponding data have been obtained at six stations located from 12°41'E up to 180° 52'E and from 52°04'N up to 68°52'N.QPP space-time distribution is shown to be correlated with that of the Earth's ionosphere current systems. The results obtained indicate that QPP of the EMF are influenced by QPP of the solar X-ray and ultraviolet radiation modulated by oscillation processes in the active solar region. 相似文献
2.
The currents on the precisely calculated magnetosphere surface previously reported have been integrated with the same accuracy as used in the surface calculation to give the magnetic field at 688 points within the magnetosphere for each of eight surfaces for the tilt of the Earth's dipole in steps of 5° between 0° and 35°. The magnetic fields have then been used to fit the coefficients of a 35 term spherical harmonic expansion of the scalar magnetic potential representing the field by the method of least squares fit. The coefficients for each of the eight surfaces were then represented as a power series in dipole tilt angle, λ so that the complete field can be given very conveniently for any λ. For λ = 0, the first two coefficients g10 and g21 are the dominant terms and the azimuthally dependent term g21 is 30 per cent less than that calculated by Mead and Midgley from older less accurate surface and field calculations. 相似文献
3.
Radiative equilibrium and radiative convective temperature profiles for the Earth's evolving atmosphere been have calculated. If the atmosphere evolved from one rich in carbon on dioxide, and deficient in oxygen, to its present composition, the temperature structure showed considerable change. The models of 3 to 4 billion years ago display steadily decreasing temperatures with altitude, being 185°K at pressures associated with the present-day upper stratosphere. A lapse rate feature similar to the present-day tropopause is not indicated until about 1 billion years ago; but the stratospheric region is approximately 15°K colder than presently found at comparable pressures. Surface temperatures approximately 10°K warmer than at present existed until nearly 1 billion years ago. When the oxygen content exceeded roughly 0.1 times the present level, surface temperatures began to decrease. If biological processes are important to carbon dioxide—ozone variations, such as has been suggested during the Ice Ages, then estimates of surface temperature should include the effects of both gases. 相似文献
4.
Hydrodynamic and electrodynamic problems of solar wind interaction with the Earth's magnetosphere on the day-side are investigated.The initial fact, well established, is that the density of the magnetic field energy in the solar wind is rather small. Magnetic field intensity and orientation are shown to determine the character of the solar wind flow around the magnetosphere. For mean parameters of the wind, if the tangential component of the magnetic field is more or equal 5γ, the flow in the magneto-sheath will be laminar. For other cases the flow is of a turbulent type.For turbulent flow, typical plasma parameters are estimated: mean free path, internal scale of inhomogeneities and dissipated energy. The results obtained are compared with experimental data.For the case of laminar flow, special attention is paid to the situation when magnetic fields of the solar wind and Earth are antiparallel. It is suggested, on the basis of solid arguments, that the southward interplanetary field diffuses from the magnetosheath into the Earth's magnetosphere. These ideas are used for the estimation of the distance to the magnetopause subsolar point. A detailed comparison with results of observation is made. The coincidence is satisfactory. Theoretical investigation has been made to a great extent for thin magnetopause with thickness δ ～ RHe-gyroradius of an electron.It is shown that during magnetospheric substorms relaxation oscillations with the period τ = 100–300 sec must appear. A theorem is proved about the appearance of a westward electrical field during the substorm development, when the magnetosphere's day-side boundary moves Earthward and about the recovery phase, when the magnetopause motion is away from the Earth, when there is an eastward electrical field.In the Appendix, plasma wave exitation in the magnetopause is considered and conductivity magnitudes are calculated, including the reduction due to the scattering by plasma turbulence. 相似文献
5.
Stellar ultraviolet light near 2500 Å is attenuated in the Earth's upper atmosphere due to strong absorption in the Hartley continuum of ozone. The intensity of stars in the Hartley continuum region has been monitored by the University of Wisconsin stellar photometers aboard the OAO-2 satellite during occultation of the star by the Earth's atmosphere. These data have been used to determine the ozone number density profile at the occultation tangent point. The results of approximately 12 stellar occultations, obtained in low latitudes, are presented, giving the nighttime vertical number density profile of ozone in the 60- to 100-km region. The nighttime ozone number density has a bulge in its vertical profile with a peak of 1 to 2×108 cm?3 at approximately 83 km and a minimum near 75 km. The shape of the bulge in the ozone number density profile shows considerable variability with no apparent seasonal or solar cycle change. The ozone profiles obtained during a geomagnetic storm showed little variation at low latitudes. 相似文献
6.
A visual albedo distribution model for all hemispheres of Io's surface has been synthesized from available Earth-based and spacecraft image and photometric data. The resulting model indicates some interesting patterns and symmetries on Io's surface: The dark polar caps are shifted off Io's rotational axis and are eliptical rather than circular in shape, with extensions toward the sub-Jupiter and anti-Jupiter points on Io; equatorial bright areas are located approximately on a great circle about Io, the plane of which is tilted approximately 15° toward Io longitude 60°. These and other indicated features may be clues to understanding the endogenic and exogenic processes that have resulted in Io's present observed surface characteristics. 相似文献
7.
Jack W. Slowey 《Planetary and Space Science》1975,23(5):879-886
Six values of the rate of rotation of the Earth's upper atmosphere have been obtained by analysis of the orbital inclinations of four balloon satellites in the intervals just before the final decay of their orbits. The effective heights of these results range from about 350 to about 675 km. The values themselves range from 0·8 to 1·4 times the Earth's rotation and correspond to zonal wind speeds between 100 m/sec westward and 200 m/sec eastward. All the results correspond to fairly specific local times and are consistent with a diurnal wind pattern in low latitudes having a strong eastward maximum near local midnight and a lesser westward maximum near 10:00 LT. They argue against the contention of a sharp decrease in the rate with respect to that of the Earth, which is supposed to begin at about 360 km. The factors involved in the determination of these values and the method used are discussed in considerable detail. 相似文献
8.
The evolution of the atmosphere of the earth 总被引：1，自引：0，他引：1
Michael H. Hart 《Icarus》1978,33(1):23-39
Computer simulations of the evolution of the Earth's atmospheric composition and surface temperature have been carried out. The program took into account changes in the solar luminosity, variations in the Earth's albedo, the greenhouse effect, variation in the biomass, and a variety of geochemical processes. Results indicate that prior to two billion years ago the Earth had a partially reduced atmosphere, which included N2, CO2, reduced carbon compounds, some NH3, but no free H2. Surface temperatures were higher than now, due to a large greenhouse effect. When free O2 appeared the temperature fell sharply. Had Earth been only slightly further from the Sun, runaway glaciation would have occured at that time. Simulations also indicate that a runaway greenhouse would have occured early in Earth's history had Earth been only a few percent closer to the Sun. It therefore appears that, taking into account the possibilities of either runaway glaciation or a runaway greenhouse effect, the continously habitable zone about a solar-type star is rather narrow, extending only from roughly 0.95 to 1.01 AU. 相似文献
9.
Stellar ultraviolet light near 1500 Å is attenuated in the Earth's upper atmosphere due to strong absorption in the Schumann-Runge continuum of molecular oxygen. The intensity of stars in the Schumann-Runge continuum region has been monitored by the University of Wisconsin stellar photometers aboard the OAO-2 satellite during occultation of the star by the Earth's atmosphere. These data have been used to determine the molecular oxygen number density profile at the occultation tangent point. The results of 14 stellar occultations obtained in low and middle latitudes are presented giving the night-time vertical number density profile of molecular oxygen in the 140–200 km region. In general, the measured molecular oxygen number density is about a factor of 2 lower than the number densities predicted by the CIRA 1965 model. Also, the number density at a given height appears to decrease with decreasing solar activity. Measurements taken at low latitudes during the August 1970 geomagnetic storm showed a decrease in the molecular oxygen number density at a given height several days after the peak of the storm followed by a slow recovery to pre-storm densities. 相似文献
10.
D.G. King-Hele 《Planetary and Space Science》1985,33(10):1145-1153
The satellite 1967-11G, which had an orbital inclination of 40°, passed through the 14th-order resonance with the Earth's gravitational field in 1974. The changes in its orbital inclination at resonance have been analysed to obtain values for four lumped 14th-order harmonics in the geopotential, with accuracies equivalent to about 5 cm in geoid height. Analysis of the eccentricity was also attempted, but did not yield useful results.As no previous satellite analysed at 14th-order resonance has had an inclination near 40°, the results have proved to be valuable in determining individual 14th-order harmonics in the geopotential. 相似文献
11.
The flux rate of cosmic rays incident on the Earth’s upper atmosphere is modulated by the solar wind and the Earth’s magnetic
field. The amount of solar wind is not constant due to changes in solar activity in each solar cycle, and hence the level
of cosmic ray modulation varies with solar activity. In this context, we have investigated the variability and the relationship
of cosmic ray intensity with solar, interplanetary, and geophysical parameters from January 1982 through December 2008. Simultaneous
observations have been made to quantify the exact relationship between the cosmic ray intensity and those parameters during
the solar maxima and minima, respectively. It is found that the stronger the interplanetary magnetic field, solar wind plasma
velocity, and solar wind plasma temperature, the weaker the cosmic ray intensity. Hence, the lowest cosmic ray intensity has
good correlations with simultaneous solar parameters, while the highest cosmic ray intensity does not. Our results show that
higher solar activity is responsible for a higher geomagnetic effect and vice versa. 相似文献
12.
The energization of positive ions in front of a cometary bow shock is investigated. Ions produced by ionization of the cometary neutrals interact with the solar wind protons to produce, among other waves, large amplitude oscillations of the ambient magnetic field. Such oscillations are convected towards the comet at the unperturbed solar wind speed far from the shock and at a lower speed closer to the shock (due to the solar wind mass loading) ; hence, they can energize the suprathermal ions by Fermi acceleration. The spatial extension of the acceleration region is of the order of 106 km and the resulting ion energy spectrum is harder than in the Earth's bow shock case. The energization of cometary ions produces an additional deceleration of the solar wind, such that the cometary bow shock of Halley-type comet may be regarded as a “cosmic ray shock”. 相似文献
13.
We present a radiative-convective modelling technique with parameterizations, for both solar and terrestrial radiation transfer, which allow the rapid computation of the mean vertical temperature profile from the ground to the thermosphere. Our method has been specifically designed for modelling the evolution of the Earth's mean vertical temperature structure due to changes in atmospheric composition, variations in the solar flux, surface albedo, cloud cover, water vapour and lapse rate, and changes in the temperature of the thermosphere which is associated with solar activity. 相似文献
14.
The dynamo explanation of Mercury's magnetic field leads to constraints on the thermal evolution of the planet. A heat-source density at least comparable to the Earth's mantle-wide average must have been retained throughout Mercury's mantle, if the core is still molten, and if Mercury's mantle possesses rheological properties similar to those of the Earth's upper mantle. 相似文献
15.
In 6 of the 7 instances where posteclipse brightening of Io has been reported by observers using blue filters, a major solar flare occurred within 10° of the sub-Jovian longitude in the 100-day interval prior to observation. In none of the 18 instances where no posteclipse brightening was observed did such a flare occur. It is proposed that a phenomenon associated with a major solar flare causes an increase in the trapped particle flux at Io's orbit by an order of magnitude. The posteclipse brightening may be caused by thermoluminescence of Io's surface material upon emergence. Alternatively, it is possible that the increase in trapped particle flux would warm the surface, creating a temporary atmosphere which would precipitate during eclipse cooling and vaporize in the period of warming after reemergence. 相似文献
16.
Kumitomo Sakurai 《Planetary and Space Science》1976,24(7):661-664
Using the data obtained from the Pioneer 10 and 11 observations, a theoretical model is proposed for the bow shock and the magentosphere of Jupiter. This indicates that the distance of the magnetopause from Jupiter on the sunlit side is (50–55) × rJ (rJ: Jupiter radius, = 7 × 109 cm) and that the ratio of the stand-off distance to this distance is about equal to or slightly larger than unity. Hence the Mach number of the solar wind seems to be less than 1.5 at Jupiter's orbit. This result necessarily leads to a blunt body model of the Jovian magnetosphere, the tail region of which is not as extended as observed in the Earth's case. 相似文献
17.
Jean Meeus 《Icarus》1975,26(2):257-267
Several statements, on which the recent book The Jupiter Effect is based, are invalid: The planets will not be “aligned” in 1982, and such an alignment has no effect on solar activity; planetary tides on the Sun are negligible; tides raised on the Sun by Venus, Earth, and Jupiter have a period of 4 mo, not 11 yr, and Wood's curve has no physical justification; there are not more sunspots visible at the eastern limb of the Sun than at the western one; the mean number of sunspots is the same at Venus' inferior and superior conjunctions; the influence of solar flares on sudden changes in the Earth's rotation and on earthquakes is not proved. This leads to the conclusion that there is no evidence for a correlation between planetary positions and earthquakes. The “Jupiter effect” does not exist. 相似文献
18.
A control network of the Saturnian satellite Iapetus has been established photogrammetrically from pictures taken by the two Voyager spacecraft. Coordinates of 62 control points have been computed and listed; pixel measurements of these points were made on 14 Voyager 1 and 66 Voyager 2 pictures. Some of these points are identified on the preliminary U.S. Geological Survey map of Iapetus and many are identified by name. The Voyager 1 and Voyager 2 pictures covered limited regions of the satellite's surface and contained no overlapping areas. The longitude system on Iapetus is defined by the crater Almeric; the 276° meridian passes through the center of this crater. The obliquity of Iapetus has been measured as 0°.4 ± 1°.6. The mean radius of Iapetus has been determined as 718 ± 8 km. 相似文献
19.
Jack D. Drummond 《Icarus》1982,49(1):143-153
A compilation of theoretical meteor radiants is presented for all numbered (through 2525) asteroids which approach the Earth's orbit to within 0.20 AU. On the basis of orbital similarity, asteroids associated with current meteor streams and Prairie Network fireballs are listed; plausible associations with medieval fireball radiants are also given. The best defunct comet candidates in terms of meteoric evidence appear to be 2101 Adonis and 2201 1947XC. Asteroids which may be either extinct comets or perturbed main belt asteroids accompanied by collisional debris (represented by fireballs) are 1917 Cuyo, 2202 Pele, 2061 Anza, and 2340 Hathor. 1566 Icarus and 1981 Midas are the only asteroids whose orbits approach to less than 0.07 AU of the Earth's orbit, have a northern radiant, and still show no certain meteoric activity. The majority of Atens, Apollos, and Amors do not pass sufficiently close (<0.07 AU) to the Earth's orbit for a reasonable expectation of meteoric activity, or have radiants south of ?20° declination, requiring southern hemisphere observations. 相似文献
20.
The course of evolution of Earth's primitive reducing atmosphere is shown to possibly have been determined to a large extent by the effect of thunder shock waves, which is comparable to the effect of solar uv radiation. The major chemical reactions occurring during a thunderstorm in the troposphere were pyrolysis of hydrocarbons, their oxidation by water vapor and their reaction with molecular nitrogen. These reactions were studied by the single-pulse shock tube technique and their rates as well as their product distributions were determined.The greenhouse effect of water vapor and acetylene enhanced oxidation by water vapor and prevented the accumulation of large graphite and polymer deposits on the Earth's surface. This is in accordance with their absence on the contemporary Earth. Changes in the frequency and power of thunderstorms, within reasonable limits, affected the rate of evolution but caused only small changes in the concentration profiles of HCN and aldehydes, which are essential for further chemical evolution in the oceans. The surface temperature and relative hydrogen concentration are shown to be of prime importance in determining the course and outcome of atmospheric evolution. 相似文献