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1.
Based on the method of dimensional analysis, the energy transfer rate from the solar wind into the magnetosphere can be characterized by a magnetic coupling parameter α on open field lines and by a viscous coupling parameter β on closed field lines. By assuming that the energy transfer rate can be monitored by the total energy dissipation rate of the magnetosphere, the histogram of α is constructed and is found to peak around ?0.1 < α < 0.1. This result implies that the energy transfer is governed primarily by the MHD dynamo process on open field lines and indicates that the ? function obtained by Perreault and Akasofu is verified as the first approximation of the solar wind-magnetosphere energy coupling function.  相似文献   

2.
It is shown that the interplanetary quantity ε(t), obtained by Perreault and Akasofu (1978), for intense geomagnetic storms, also correlates well with individual magnetospheric substonns. This quantity is given by ε(t) = VB2sin4 (θ2)lo2, where V and B denote the solar wind speed and the magnitude of the interplanetary magnetic field (IMF), respectively, and θ denotes the polar angle of the IMF; lo is a constant ? 7 Earth radii. The AE index is used in this correlation study. The correlation is good enough to predict both the occurrence and intensity of magnetospheric substonns observed in the auroral zone, by monitoring the quantity ε(t) upstream of the solar wind.  相似文献   

3.
On 11 November 1976, after a magnetically quiet period with the interplanetary magnetic field (IMF) directed northward, a sudden southward turning of the IMF immediately led to a world-wide intensification of convection which was observed to start almost simultaneously at stations within the auroral zone and polar cap. The two-dimensional equivalent current system over the northern hemisphere had a typical two-cell convection pattern with a maximum disturbance of ΔH = ?300 nT observed on the morningside in the westward electrojet region. This enhancement of activity ended after 35 min in a localized substorm onset in the midnight sector over Scandinavia.The recordings made in this area indicate large fluctuations of various ionospheric parameters starting several minutes before the substorm onset. Two subsequent stages can be resolved: (1) high-energy particle precipitation recorded by balloon X-ray detectors and maximum ionospheric current density increase, while the electrojet halfwidth shrinks and the total electrojet current becomes weaker; (2) the maximum ionospheric current density stays constant and the high-energy particle precipitation decreases, while the auroral brightness increases and the total electrojet current and its half-width show a growing trend prior to the final breakup. A suggestion is made that the time interval of these two stages should be called “trigger phase”. A short discussion explains the trigger phase observations in a magnetospheric scale. The energy coupling between solar wind and magnetosphere during the pre-substorm phases is discussed by utilizing the energy coupling function ? defined by Perreault and Akasofu (Geophys. J. R. Astr. Soc.54, 547, 1978). The ? values appear to be on substorm level during the period of enhanced convection. A good correlation between ? and the growth of the Joule heating rate (estimated from the AE data) is found in the beginning, but during the last 20 min before substorm triggering ? is high while the Joule heating rate decreases. The behaviour of ? during the two stages of the trigger phase suggests that the start of the trigger phase is purely internally controlled while the length of the trigger phase and the final substorm onset may be influenced by the variation in ?.  相似文献   

4.
An expression for the magnetopause reconnection power based on the dawn-dusk component of the reconnection electric field, that reduces to the substorm parameter ? for the limit that involves equal geomagnetic (BG) and magnetosheath (BM) magnetic field amplitudes at the magnetopause, is contrasted with the expression based on the whole reeonnection electric field vector (Gonzalez, 1973). The correlation examples of this report show that this (more general) expression for the reconnection power seems to correlate with the empirical dissipation parameter UT (Akasofu, 1981), with slightly better correlation coefficients than those obtained from similar correlations between the parameter ? and UT Thus, these (better) correlations show up for the more familiar values of the ratio BG/BM > 1. Nevertheless, the (expected) relatively small difference that seems to exist between these correlation coefficients suggests that, for practical purposes, the parameter ? could be used as well (instead of the more general expression) in similar correlation studies due to its simpler format. On the other hand, studies that refer mainly to the difference in the magnitudes of ? and of the more general expression are expected to give results with less negligible differences.  相似文献   

5.
Assuming that the formation of the ring current belt is a direct consequence of an enhanced convection of plasma sheet protons, the expression for the energy injection rate UR is formulated as a function of the cross-tail potential drop φCT for a simple electric field-magnetic field model. It is shown that an approximate expression for UR thus formulated consists of two parts: (i) the first part UR1, which is linearly proportional to φCT, is supplied by the corotation electric field and (ii) the second part UR>2, which is proportional to φ2CT, is supplied by the solar wind energy input to the magnetosphere. The second part UR2 dominates the ring current energy input when the cross-tail potential drop φCT is greater than ～ 95 keV, namely during disturbed periods. An important finding is that the second part UR2 of the ring current energy input is shown to be proportional to the solar wind-magnetosphere energy coupling function ?, recovering the observationally established relationship. Therefore, the present study verifies that an enhanced convection is the cause of the ring current formation.  相似文献   

6.
A high time resolution study of the relationship between the solar wind-magnetosphere energy coupling function ? and the total energy dissipation rate UT of the magnetosphere is made using 5-min average values of solar wind data and of the geomagnetic indices AE and Dst. All the results are essentially the same as those obtained by the earlier studies which were based on the hourly average data set. Therefore, we confirm that the magnetosphere is primarily a driven system.  相似文献   

7.
A solar wind parameter ε, known as the energy coupling function, has been shown to correlate with the power consumption in the magnetosphere. It is shown in the present paper that the parameter ε can be identified semi-quantitatively as the dynamo power delivered from the solar wind to an open magnetosphere. This identification not only provides a theoretical basis for the energy coupling function, but also constitutes an observational verification of the solar wind-magnetosphere dynamo along the magnetotail. Moreover, one can now conclude that a substorm results when the dynamo power exceeds 1018 ergs ?1.  相似文献   

8.
It is usually assumed that the dipole radiation at the spin frequency Wd is the only source of braking torque on pulsars (the POG hypothesis), but certain observations cast doubt on this. In this paper, we discuss the effect of elctromagnetic braking near the light cylinder Wem without using the POG hypothesis. We found Wem ∝ P?3.2 (P is the pulsar period), and the total power Lt ∝ P?3.2 (if Lt ∝ Wem). A correlation analysis between Lt and Pn for a sample of 15 pulsars gives n = ?3.1, in agreement with our theoretical expectations.Our analysis based on observations shows that Wem is important or even dominant in some cases. In these cases, the evolutionary path (Fig.2) is very different from that given in /4/ where Wd is assumed to be dominant. The actual braking mechanism could be a superposition of the two (Fig.3).The gap in the P ～ P? diagram found by Ferguson /5/ for a sample of 80-odd pulsars persists in a larger sample of 199 pulsars. This gap, if real, implies that, for a certain range of parameter values, a neutron star is unstable, while it is stable on either side of the range.  相似文献   

9.
The outer regions (r > 2.3 Rj; Rj = radius of Jupiter) of the magnetosphere of Jupiter will systematically accumulate plasma. If sufficient plasma accumulates, the field lines must open to allow the plasma to escape. Available energy sources appear able to supply plasma at a high enough rate to keep the field lines constantly open beyond about 60 RJ. We suggest that the solar wind interaction with Jupiter may be essentially different from that with the Earth, with the Jovian magnetosphere opening up to form a planetary wind.  相似文献   

10.
The recent finding of the solar wind-magnetosphere energy coupling function ε has advanced significantly our understanding of magnetospheric disturbances. It is shown that the magnetosphere-ionosphere coupling system responds somewhat differently to three different input energy flux levels of ε. As ε increases from < 1017 erg s?1 to > 019 erg s?1, typical responses of the magnetosphere-ionosphere coupling system are:ε < 1017 erg s?1: an enhancement of the Sqp, etc,ε ≈ 1018 erg s?1: substorm onset,1018 erg s?1 < ε < 1019 erg s?1f: a typical substorm,ε >1019 erg s?1: an abnormal growth of the ring current belt, resulting in a magnetospheric storm.It is stressed that the magnetospheric substorm results as a direct response of the magnetosphere to a rise and fall of ε above ≈ 1018 erg s?1, so that it is not caused by a sudden conversion of magnetic energy accumulated prior to substorm onset. The variety of the development of the main phase of geomagnetic storms is also primarily controlled by ε.  相似文献   

11.
Jovian decametric radio wave emissions that were observed at Goddard Space Flight Center, U.S.A. for a period from 1 October to 31 December, 1974 and data obtained at Mt Zao observatory, Tohoku University, Japan, for a period from 14 July to 6 December, 1975 have been used to investigate the relationship of the occurrence of the Jovian decametric radio waves (JDW), from the main source, to the geomagnetic disturbance index, ΣKp. The dynamic cross-correlation between JDW and ΣKp indicates an enhanced correlation for certain values of delay time. The delay time is consistent with predicted values based on a model of rotating turbulent regions in interplanetary space associated with two sector boundaries of the interplanetary magnetic field, i.e. the rotating sector boundaries of the interplanetary magnetic field first encounter the Earth's magnetosphere producing the geomagnetic field disturbances, and after a certain period, they encounter the Jovian magnetosphere. There are also cases where the order of the encounter is opposite, i.e. the sector boundaries encounter first Jovian magnetosphere and encounter the Earth's magnetosphere after a certain period.  相似文献   

12.
Using ion-electron fluid parameters derived from Cassini Plasma Spectrometer (CAPS) observations within Saturn's inner magnetosphere as presented in Sittler et al. [2006a. Cassini observations of Saturn's inner plasmasphere: Saturn orbit insertion results. Planet. Space Sci., 54, 1197-1210], one can estimate the ion total flux tube content, NIONL2, for protons, H+, and water group ions, W+, as a function of radial distance or dipole L shell. In Sittler et al. [2005. Preliminary results on Saturn's inner plasmasphere as observed by Cassini: comparison with Voyager. Geophys. Res. Lett. 32(14), L14S04), it was shown that protons and water group ions dominated the plasmasphere composition. Using the ion-electron fluid parameters as boundary condition for each L shell traversed by the Cassini spacecraft, we self-consistently solve for the ambipolar electric field and the ion distribution along each of those field lines. Temperature anisotropies from Voyager plasma observations are used with (T⊥/T∥)W+∼5 and (T⊥/T∥)H+∼2. The radio and plasma wave science (RPWS) electron density observations from previous publications are used to indirectly confirm usage of the above temperature anisotropies for water group ions and protons. In the case of electrons we assume they are isotropic due to their short scattering time scales. When the above is done, our calculation show NIONL2 for H+ and W+ peaking near Dione's L shell with values similar to that found from Voyager plasma observations. We are able to show that water molecules are the dominant source of ions within Saturn's inner magnetosphere. We estimate the ion production rate SION∼1027 ions/s as function of dipole L using NH+, NW+ and the time scale for ion loss due to radial transport τD and ion-electron recombination τREC. The ion production shows localized peaks near the L shells of Tethys, Dione and Rhea, but not Enceladus. We then estimate the neutral production rate, SW, from our ion production rate, SION, and the time scale for loss of neutrals by ionization, τION, and charge exchange, τCH. The estimated source rate for water molecules shows a pronounced peak near Enceladus’ L shell L∼4, with a value SW∼2×1028 mol/s.  相似文献   

13.
Recent observations of partial penetration of the IMF By into the magnetosphere (Fairfield, 1979; Cowley and Hughes, 1983) are shown to agree with the idea of a magnetopause current Ky, induced by IMF By (Primdahl and Spangslev, 1983). The slow decay of Ky, caused by Joule heat losses in the cusp ionospheres is responsible for the appearance (on the average) of a fraction of IMF By inside the magnetosphere, and this also explains the large statistical scatter of the data. A decay time constant of 4–5 days is derived from the average fraction of IMF By observed inside the magnetosphere in good agreement with the 7-day time constant previously proposed.  相似文献   

14.
There are a few methods of measuring pulse widths. Among the most often used pulse widths there are Wpp (the distance between two peak value points), W50 (the width at the place of 50% of the highest peak intensity) and W10 (the width at the place of 10% of the highest peak intensity). In addition, there are also the width Wc50 at the place of 50% of their respective intensities and the width Wc10 at the place of 10% of the respective intensities of the two outermost components. The data of the pulse profiles of the sample of 16 double-cone peak pulsars and 7 core-cone triple peak pulsars at 1.4 GHz are utilized to measure 5 kinds of pulse widths. The pulsars with the data of the magnetic inclination α and impact angle β are employed to derive the corresponding radiation beam radius ρ, and the relation between ρ and the pulsar period P, ρ ∝ P?0.5, is verified. Via a comparison between the qualities of the relation between ρ and P derived from the 5 kinds of pulse widths it is found that the width between the outermost components is better than any one of the first 3 kinds of widths, of which the correlative relation obtained from the Wc50 width is the best. From this it is considered that Wc50 is the measured value that can fully reflect the emission beam width. The symmetry of the pulse profile is also discussed and it is found that from the comparison with the preceding cone emission component the following cone emission component is much closer to the core emission component, and the widths of the two cone emission components are basically the same according to statistics.  相似文献   

15.
We present new results of Cassini's T9 flyby with complementary observations from T18. Based on Cassini plasma spectrometer (CAPS) and Cassini magnetometer (MAG), compositional evidence shows the upstream flow for both T9 and T18 appears composed of light ions (H+ and H2+), with external pressures ∼30 times lower than that for the earlier TA flyby where heavy ions dominated the magnetospheric plasma. When describing the plasma heating and sputtering of Titan's atmosphere, T9 and T18 can be considered interactions of low magnetospheric energy input. On the other hand, T5, when heavy ion fluxes are observed to be higher than typical (i.e., TA), represents the limiting case of high magnetospheric energy input to Titan's upper atmosphere. Anisotropy estimates of the upstream flow are 1<T⊥/T‖<3 and the flow is perpendicular to B, indicative of local picked up ions from Titan's H and H2 coronae extending to Titan's Hill sphere radius. Beyond this distance the corona forms a neutral torus that surrounds Saturn. The T9 flyby unexpectedly resulted in observation of two “wake” crossings referred to as Events 1 and 2. Event 2 was evidently caused by draped magnetosphere field lines, which are scavenging pickup ions from Titan's induced magnetopause boundary with outward flux ∼2×106 ions/cm2/s. The composition of this out flow is dominated by H2+ and H+ ions. Ionospheric flow away from Titan with ion flux ∼7×106 ion/cm2/s is observed for Event 1. In between Events 1 and 2 are high energy field aligned flows of magnetosphere protons that may have been accelerated by the convective electric field across Titan's topside ionosphere. T18 observations are much closer to Titan than T9, allowing one to probe this type of interaction down to altitudes ∼950 km. Comparisons with previously reported hybrid simulations are made.  相似文献   

16.
Observations made by HEOS-2 of low energy electrons and protons in the high latitude magnetosphere are presented. Plasma in the magnetosphere is observed in the cusp (which extend down to low altitudes) and over large areas adjacent to the high latitude magnetopause both on the dayside and on the nightside (the entry layer and the plasma mantle respectively).A comparative study of the plasma properties in the various parts of the magnetosphere is performed. An ion bulk motion directed tailward along the geomagnetic field lines is observed both in the entry layer and in the plasma mantle; in the cusp, on the contrary, the bulk motion is practically absent. Moreover the electron thermal anisotropy is parallel to the magnetic field in the magnetosheath, and perpendicular to it in the plasma mantle. One possible explanation (suggested by Rosenbauer et al., 1975) of the origin of these populations is that plasma, penetrated from the magnetosheath in the entry layer, flows tailward along the field lines, is then reflected in the cusp region and convected in the plasma mantle.  相似文献   

17.
Cosmic energy equation represents the law of conservation of energy in the region expanding with time as the universe expands. It gives the evolution of kinetic and correlation potential energy with time in a cluster expanding as the universe expands. To understand the clustering of galaxies under the influence of gravitational force, cosmic energy equation is of great help. We use cosmic energy equation for extended structures (galaxies with halos) to analyse the gravitational galaxy clustering in different ways. We try to understand the influence of expansion on the clustering by deriving the relation between correlation parameter b V and scale factor R. We also derive the relation between the peculiar kinetic energy K and correlation parameter to know that when peculiar kinetic energy dominates over the kinetic energy of galaxies due to expansion. Besides, the evolution of specific heat and energy provides the information regarding the different states of clustering.  相似文献   

18.
During the last sunspot maximum, major auroras occurred over Boston, MA (L = 3.1) on 23/24 March 1969 and 8/9 March 1970, during which optical and incoherent scatter radar measurements were made simultaneously from the Blue Hill Observatory and Millstone Field Station, respectively. The paper presents the results of these measurements and attempts a self-consistent interpretation of them. It is found that a major increase (5–10 times) in the abundance of molecular species (O2 and N2) at F-region heights must have occurred; this was not accompanied by any appreciable increase in the major neutral species, atomic oxygen. From the radar data, the energy input to the F-region can be separated into direct heating by secondary electrons, downward heat flow from the magnetosphere and a low-energy non-ionizing electron flux. The total observed intensity of the predominant optical emission from atomic oxygen at 6300 Å can then be predicted satisfactorily by summing the contributions to this emission from impact excitation by ambient electrons, from the low-energy precipitating electrons and from dissociative recombination.  相似文献   

19.
The correlation between the proton flux intensity I p with the energies E p > 1?100 MeV and radio burst parameters for 107 solar energetic events is considered using the observation data for 1989?C2005 obtained with GOES and Wind satellites, as well as the Radio Solar Telescope Network (RSTN). It has been revealed that 73 and 77% of the events were accompanied by type-II radio bursts in the meter (m II, 25?C299 MHz) and the decameter-hectometer (DH II, 20 kHz?C14 MHz) wavelength ranges, respectively. The correlation coefficient between I p and the frequency drift velocity of the type-II bursts V II did not exceed 0.40. As V II increased, the intensity of I p increased for the m-II bursts and decreased for the DH-II bursts. Coronal shock waves accelerate protons more efficiently than interplanetary waves, and their contribution to acceleration increases with an increase in the particle energy E p . The acceleration of solar energetic particles in the region of the flare energy release is predominant.  相似文献   

20.
Dust-ion-acoustic (DIA) waves in an unmagnetized dusty plasma system consisting of inertial ions, negatively charged immobile dust, and superthermal (kappa distributed) electrons with two distinct temperatures are investigated both numerically and analytically by deriving Korteweg–de Vries (K-dV), modified K-dV (mK-dV), and Gardner equations along with its double layers (DLs) solutions using the reductive perturbation technique. The basic features of the DIA Gardner solitons (GSs) as well as DLs are studied, and an analytical comparison among K-dV, mK-dV, and GSs are also observed. The parametric regimes for the existence of both the positive as well as negative SWs and negative DLs are obtained. It is observed that superthermal electrons with two distinct temperatures significantly affect on the basic properties of the DIA solitary waves and DLs; and depending on the parameter μ c (the critical value of relative electron number density μ e1), the DIA K-dV and Gardner solitons exhibit both compressive and rarefactive structures, whereas the mK-dV solitons support only compressive structures and DLs support only the rarefactive structures. The present investigation can be very effective for understanding and studying various astrophysical plasma environments (viz. Saturn magnetosphere, pulsar magnetosphere, etc.).  相似文献   

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