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1.
Two Doppler imaging systems (DIS) or wide-field imaging Fabry-Perot interferometers (FPI), have recently been commissioned, one at the Auroral Station, Adventdalen, Longyearbyen, Svalbard, and the second at the IRF, Kiruna, Sweden. These instruments can provide wide-field (600 * 800 km) images of neutral wind flows in the upper thermosphere, by measuring the Doppler shift of the atomic oxygen forbidden near 630 nm, which is emitted from an altitude of approximately 240 km. From the instrument in Svalbard, at mid-winter, it is possible to observe the dayside polar cusp and the polar cap throughout the entire day, whereas from Kiruna, the night-time auroral oval is observable during the hours of darkness. Measurements of thermospheric dynamics from the DIS can be used in conjunction with observations of ionospheric plasma flows and thermal plasma densities by the EISCAT-Svalbard radar (ESR) and by EISCAT, along with other complementary observations by co-located instruments such as the auroral large-scale imaging system (ALIS). Such combined data sets will allow a wide range of scientific studies to be performed concerning the dynamical response of the thermosphere and ionosphere, and the important energetic and momentum exchange processes resulting from their complex interactions. These processes are particularly important in the immediate vicinity of the polar cusp and within the auroral oval. Early results from Svalbard in late 1995 will be discussed. The DIS in Kiruna observed two interesting geomagnetic disturbances in early 1997, the minor geomagnetic storm of 10, 11 January, and the disturbed period from 7–10 February. During these events, the thermospheric wind response showed some interesting departures from the average behaviour, which we attribute to the result of strong and variable Lorenz forcing (ion drag) and Joule and particle heating during these geomagnetic disturbances.  相似文献   

2.
Plasma patches are regions of enhanced ionization that are created in the dayside cusp or equatorward of the cusp in the sunlit hemisphere during northward interplanetary magnetic field. After formation, and a change to a southward interplanetary magnetic field, they drift across the polar cap with the prevailing convection speed. As a plasma patch propagates, charge exchange reactions occur, which lead to the production of both ion and neutral particles throughout the patch. In the region directly above the patch, an upward jet of H+ and O+ forms. This ion jet, in turn, acts to produce an upward flux of neutral H and O stream particles because of charge exchange reactions between the ion jet and the background neutral atmosphere. A three-dimensional, time-dependent model of the ion and neutral polar winds was used in order to study the evolution of the neutral stream particles that are produced in a ‘representative’ propagating plasma patch, with the anticipation that the neutral stream particles produced by the ion jet would display a distinct signature. However, the outflow of neutral H atoms above a patch is only slightly visible in the simulation due to a continuous outflow flux of H (∼109 cm−2 s−1) across the entire polar cap. On the other hand, the upward flux of neutral O from the patch is more dependent on both the state of the ionosphere and the amount of heating, with increased upward fluxes over areas where the heating is high. Typically, the upward neutral O streams are predominantly located in the pre-midnight auroral oval.  相似文献   

3.
First results are presented from a 3-D, time dependent, high resolution, nested grid model that has been developed to study mesoscale processes in the global, coupled thermosphere–ionosphere system. This new Thermosphere–Ionosphere Nested Grid (TING) model, which is an extension of the National Center for Atmospheric Researchs thermosphere–ionosphere general circulation model (NCAR–TIGCM), runs on a UNIX workstation. The TING model simultaneously calculates global (coarse resolution) and local (high resolution) distributions of neutral and plasma winds, temperature and composition. It is comprised of two coupled codes—a global TIGCM and an adjustable nested grid code which uses the same solvers as the TIGCM, but has higher spatial and temporal resolution. The size, location and level of nesting of the high resolution grid(s) are adjustable to suit the specific application. The coupling between the coarse (TIGCM) grid and the nested interior grids is via a one-way interaction scheme. In this scheme, the TIGCM output influences the nested grid model by providing initial conditions and temporally evolving boundary conditions, but the outputs from the nested grid are not permitted to influence the TIGCM. Diurnally-reproducible results of the TING model are presented for solar-maximum, winter solstice, geomagnetically-quiet conditions. The TING model successfully simulates well-known thermosphere–ionosphere features that are smeared or not modeled at the spatial resolutions used in standard TIGCMs. These include the sub-auroral electron density trough, the polar cap hole and the polar cap tongue of ionization.  相似文献   

4.
This topical review provides an overview of the progress achieved under Project 3.1, entitled Global Aspects of Plasma Structures (GAPS) during the lifetime of the Solar Terrestrial Energy Program (STEP) from 1990–97. The mandate of the GAPS project covered middle and high latitude plasma structuring. However, given the requirement of limited length for this overview, only high latitude studies will be covered because of the particularly collaborative nature of the effort, made possible by an international program such as STEP. High latitude plasma structuring studies have progressed from joint experimental campaigns involving many locations and diagnostic techniques, and several focused international workshops that united experimenters and modelers. They have provided the groundwork for studying the macroscale (hundreds of km) and mesoscale (km and smaller) plasma structures at high latitudes under two distinct configurations of the interplanetary magnetic field (IMF).When the IMF is directed southward, we observe macroscale, enhanced density structures known as patches. We have documented much on their origin, modification by the electric field structure in the cusp, airglow signatures in the polar cap, interaction with the neutral medium, mesoscale structuring causing scintillations, convection through the polar cap, and eventual exit into the auroral oval. This has led to several modeling efforts, demonstrating patch formation via temporal changes in the large-scale flow configuration in the cusp. Additionally, we have successfully linked the climatology of the macroscale structure model to the mesoscale structure in the polar regions, an advance that may lead to truly predictive irregularity models for forecasting effects on communication and navigation systems during the upcoming solar maximum.For northward IMF conditions, we have advanced our ability to simulate Sun-aligned arcs using a magnetosphere–ionosphere (M–I) coupled model, driven by realistic magnitudes of electric fields, conductivities and currents. The simulation has been enabled by utilizing an extensive ground-based optical database supported by satellite measurements of their morphological characteristics, including their dawn-dusk motion, dependence on IMF By, and propensity for multiple structuring. We soon expect significant advances resulting from several newly established powerful instruments in the northern and southern polar regions.  相似文献   

5.
Polar rain has a beautiful set of symmetry properties, individually established, but not previously discussed collectively, which can be organized by a single unifying principle. The key polar rain properties are favored hemisphere (controlled by the interplanetary magnetic field Bx), dawn/dusk gradient (IMF By), merging rate (IMF Bz or more generally dΦMP/dt), nightside/dayside gradient, and seasonal effect. We argue that all five properties involve variants on a single theme: the further downstream a field line exits the magnetosphere (or less directly points toward the solar wind electron heat flux), the weaker the polar rain. This effect is the result of the requirements of charge quasi-neutrality, and because the ion thermal velocity declines and the tailward ion bulk flow velocity rises moving down tail from the frontside magnetopause.Polar cap arcs (or more properly, high-latitude sun-aligned arcs) are largely complementary to the polar rain, occurring most frequently when the dayside merging rate is low, and thus when polar rain is weak. Sun-aligned arcs are often considered as originating either in the polar rain or the expansion of the plasma sheet into the polar cap. In fact three quite distinct types of sun-aligned high-latitude arcs exist, two common, and one rare. One type of arc occurs as intensifications of the polar rain, and is common, but weak, typically <0.1 ergs/cm2 s, and lacks associated ion precipitation. A second category of Sun-aligned arcs with energy flux >0.1 ergs/cm2 s usually occurs adjacent to the auroral oval, and includes ion precipitation. The plasma regime of these common, and at times intense, arcs is often distinct from the oval which they abut. Convection alone does not specify the open/closed nature of these arcs, because multiple narrow convection reversals are common around such arcs, and the arcs themselves can be embedded within flows that are either sunward or anti-sunward. These observational facts do not neatly fit into either a plasma sheet origin or a polar rain origin (e.g., the necessity to abut the auroral oval, and the presence of ions does not fit the properties of polar rain, which can in any event be nearly absent for northward interplanetary magnetic field). One theory is that such arcs are associated with merging tailward of the cusp. Both of these common types of sun-aligned arcs fade within about 30 min of a southward IMF turning.The third, and rarest, category of sun-aligned arcs are intense, well detached from the auroral oval, contain plasma sheet origin ion precipitation as well as electrons, and persist for hours after a southward turning. These intense detached sun-aligned arcs can rapidly cross the polar cap, sometimes multiple times. Most events discussed in the literature as “theta-aurora” do not fit into this category (for example, although they may appear detached in images, they abut the oval in particle data, and do not have the persistence of detached events under southward IMF turnings). It is possible that no single theory can account for all three types of sun-aligned arcs.Solar energetic particle (SEP) events are at times used to demarcate polar cap open/closed boundaries. Although this works at times, examples exist where this method fails (e.g., very quiet conditions for which SEP reaches below L=4), and the method should be used with caution. Finally, it is shown that, although it is rare, the polar cap can at times completely close.  相似文献   

6.
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7.
A study has been made of the interaction between the thermosphere and the ionosphere at high latitudes, with particular regard to the value of the O+-O collision parameter. The European incoherent scatter radar (EISCAT) was used to make tristatic measurements of plasma parameters at F-region altitudes while simultaneous measurements of the neutral wind were made by a Fabry-Perot interferometer (FPI). The radar data were used to derive the meridional neutral winds in a way similar to that used by previous authors. The accuracy of this technique at high latitudes is reduced by the dynamic nature of the auroral ionosphere and the presence of significant vertical winds. The derived winds were compared with the meridional winds measured by the FPI. For each night, the value of the O+-O collision parameter which produced the best agreement between the two data sets was found. The precision of the collision frequency found in this way depends on the accuracy of the data. The statistical method was critically examined in an attempt to account for the variability in the data sets. This study revealed that systematic errors in the data, if unaccounted for by the analysis, have a tendency to increase the value of the derived collision frequency. Previous analyses did not weight each data set in order to account for the quality of the data; an improved method of analysis is suggested.  相似文献   

8.
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9.
Flow bursts within the ionosphere are the ionospheric signatures of flow bursts in the plasma sheet and have been associated with poleward boundary intensifications (PBIs). Some PBIs extend equatorward from the polar cap boundary, where they can be roughly divided into north–south-aligned and east–west-aligned structures. In this paper, we present two flow burst events observed by the new Poker Flat Advanced Modular Incoherent Scatter Radar (PFISR) in the pre-midnight auroral zone on 28 April 2007, one towards the west and the other towards the east. In both cases, enhanced flows lasted for about 8–10 min with peak velocities exceeding 1500 m/s. The concurrently measured electron density showed that the flow bursts occurred in low conductivity regions. However, near the poleward (equatorward) edge of the westward (eastward) flow burst, strong electron density enhancements were observed in the E region, indicating the presence of discrete auroral arcs. Auroral images from the Polar spacecraft were available at the time of the eastward flow burst and they indicate that this burst was associated with an east–west-aligned auroral structure that connected at later MLT to a north–south structure. In addition, simultaneous precipitating particle energy spectrum measured by the the Defense Meteorological Satellites Program (DMSP) F13 satellite reveals that this auroral structure resulted from mono-energetic electron precipitation associated with a significant field-aligned potential drop. These observations show direct evidence of the relationship between flow bursts, field-aligned currents and auroral intensifications, and suggest that eastward/westward flow bursts are associated with east–west-oriented PBI structures that have extended well within the plasma sheet. This is in contrast to the equatorward-directed flow that has been previously inferred for PBIs near the polar cap boundary and for north–south auroral structures. This paper illustrates the use of the PFISR radar for studying the magnetosphere–ionosphere coupling of flow bursts.  相似文献   

10.
The presence of polar patches as observed simultaneously in the same magnetic meridian of opposite nightside ionospheres by coherent and incoherent scatter radars are described. The patches appear to be related to variations either in the Bz or By component of the interplanetary magnetic field which cause transient merging on the dayside magnetopause. The passage and characteristics of polar patches as they traverse the polar cap into the nightside auroral oval are not significantly affected by the occurrence of small substroms. This study illustrates how the observations of polar patches in the nightside high-latitude ionosphere could be of great value in determining their formation process.  相似文献   

11.
In a previous publication we used results from a coupled thermosphere-ionosphere-plasmasphere model to illustrate a new mechanism for the formation of a large-scale patch of ionisation arising from a rapid polar cap expansion. Here we describe the thermospheric response to that polar cap expansion, and to the ionospheric structure produced. The response is dominated by the energy and momentum input at the dayside throat during the expansion phase itself. These inputs give rise to a large-scale travelling atmospheric disturbance (TAD) that propagates both antisunward across the polar cap and equatorward at speeds much greater than both the ion drifts and the neutral winds. We concentrate only on the initially poleward travelling disturbance. The disturbance is manifested in the neutral temperature and wind fields, the height of the pressure level surfaces and in the neutral density at fixed heights. The thermospheric effects caused by the ionospheric structure produced during the expansion are hard to discern due to the dominating effects of the TAD.  相似文献   

12.
It has been clearly established that there is a substantial outflow of ionospheric plasma from the Earth's ionosphere in both the northern and southern polar regions. The outflow consists of both light thermal ions (H+ and He+) and an array of energized ions (NO+, O2+, N2+, O+, N+, He+, and H+). If the outflow is driven by thermal pressure gradients in the ionosphere, the outflow is called the “classical” polar wind. On the other hand, if the outflow is driven by energization processes either in the auroral oval or at high altitudes in the polar cap, the outflow is called the “generalized” polar wind. In both cases, the field-aligned outflow occurs in conjunction with magnetospheric convection, which causes the plasma to drift into and out of the sunlit hemisphere, cusp, polar cap, nocturnal auroral oval, and main trough. Because the field-aligned and horizontal motion are both important, three-dimensional (3-D) time-dependent models of the ionosphere–polar wind system are needed to properly describe the flow. Also, as the plasma executes field-aligned and horizontal motion, charge exchange reactions of H+ and O+ with the background neutrals (H and O) act to produce low-energy neutrals that flow in all directions (the neutral polar wind). This review presents recent simulations of the “global” ionosphere–polar wind system, including the classical, generalized, and neutral polar winds. The emphasis is on displaying the 3-D and dynamical character of the polar wind.  相似文献   

13.
We present two case studies in the night and evening sides of the auroral oval, based on plasma and field measurements made at low altitudes by the AUREOL-3 satellite, during a long period of stationary magnetospheric convection (SMC) on November 24, 1981. The basic feature of both oval crossings was an evident double oval pattern, including (1) a weak arc-type structure at the equatorial edge of the oval/polar edge of the diffuse auroral band, collocated with an upward field-aligned current (FAC) sheet of ≈1.0 μA m−2, (2) an intermediate region of weaker precipitation within the oval, (3) a more intense auroral band at the polar oval boundary, and (4) polar diffuse auroral zone near the polar cap boundary. These measurements are compared with the published magnetospheric data during this SMC period, accumulated by Yahnin et al. and Sergeev et al., including a semi-empirical radial magnetic field profile BZ in the near-Earth neutral sheet, with a minimum at about 10–14 RE. Such a radial BZ profile appears to be very similar to that assumed in the “minimum B/cross-tail line current” model by Galperin et al. (GVZ92) as the “root of the arc”, or the arc generic region. This model considers a FAC generator mechanism by Grad-Vasyliunas-Boström-Tverskoy operating in the region of a narrow magnetic field minimum in the near-Earth neutral sheet, together with the concept of ion non-adiabatic scattering in the “wall region”. The generated upward FAC branch of the double sheet current structure feeds the steady auroral arc/inverted-V at the equatorial border of the oval. When the semi-empirical BZ profile is introduced in the GVZ92 model, a good agreement is found between the modelled current and the measured characteristics of the FACs associated with the equatorial arc. Thus the main predictions of the GVZ92 model concerning the “minimum-B” region are consistent with these data, while some small-scale features are not reproduced. Implications of the GVZ92 model are discussed, particularly concerning the necessary conditions for a substorm onset that were not fulfilled during the SMC period.  相似文献   

14.
A discussion is given of plasma flows in the dawn and nightside high-latitude ionospheric regions during substorms occurring on a contracted auroral oval, as observed using the EISCAT CP-4-A experiment. Supporting data from the PACE radar, Greenland magnetometer chain, SAMNET magnetometers and geostationary satellites are compared to the EISCAT observations. On 4 October 1989 a weak substorm with initial expansion phase onset signatures at 0030 UT, resulted in the convection reversal boundary observed by EISCAT (at \sim0415 MLT) contracting rapidly poleward, causing a band of elevated ionospheric ion temperatures and a localised plasma density depletion. This polar cap contraction event is shown to be associated with various substorm signatures; Pi2 pulsations at mid-latitudes, magnetic bays in the midnight sector and particle injections at geosynchronous orbit. A similar event was observed on the following day around 0230 UT (\sim0515 MLT) with the unusual and significant difference that two convection reversals were observed, both contracting poleward. We show that this feature is not an ionospheric signature of two active reconnection neutral lines as predicted by the near-Earth neutral model before the plasmoid is “pinched off”, and present two alternative explanations in terms of (1) viscous and lobe circulation cells and (2) polar cap contraction during northward IMF. The voltage associated with the anti-sunward flow between the reversals reaches a maximum of 13 kV during the substorm expansion phase. This suggests it to be associated with the polar cap contraction and caused by the reconnection of open flux in the geomagnetic tail which has mimicked “viscous-like” momentum transfer across the magnetopause.  相似文献   

15.
From data of the European incoherent scatter radar EISCAT, and mainly from its tristatic capabilities, statistical models of steady convection in the auroral ionosphere were achieved for various levels of magnetic activity. We propose here to consistently extend these models to the polar cap, by avoiding the use of a predefined convection pattern. Basically, we solve the second-order differential equation governing the polar cap convection potential with the boundary conditions provided by these models. The results display the classical twin-vortex convection pattern, with the cell centres around 17 MLT for the evening cell and largely shifted towards midnight (3–3.5 MLT) for the morning cell, both slightly moving equatorward with activity. For moderate magnetic activities, the convection now appears approximately oriented along the meridian from 10:00 MLT to 22:00 MLT, while in more active situations, it enters the polar cap at prenoon times following the antisunward direction, and then turns to exit around 21:00 MLT. Finally, from these polar cap patterns combined with the auroral statistical models, we build analytical models of the auroral and polar convection expected in steady magnetic conditions.  相似文献   

16.
A case is described of multiple current sheets crossed by the MAGION-2 satellite in the near-midnight quieting auroral oval. The data were obtained by the magnetometer experiment onboard. Results show during a quieting period after a preceding substorm, or during an early growth phase of the next substorm, two double-sheet current bands, POLE and EQUB, located at respectively the polar and equatorial borders of the auroral oval separated by about 500 km in latitude. This is consistent with the double-oval structure during recovery introduced by Elphinstone et al. (1995). Within the POLE, the magnetic field data show simultaneous existence of several narrow parallel bipolar current sheets within the upward current branch (at 69.5–70.3° invariant latitude) with an adjacent downward current branch at its polar side at (70.5–71.3°). The EQUB was similarly stratified and located at 61.2–63.5° invariant latitude. The narrow current sheets were separated on average by about 35 km and 15 km, respectively, within the POLE and EQUB. A similar case of double-oval current bands with small-scale structuring of their upward current branches during a quieting period is found in the data from the MAGION-3 satellite. These observations contribute to the double-oval structure of the late recovery phase, and add a small-scale structuring of the upward currents producing the auroral arcs in the double- oval pattern, at least for the cases presented here. Other observations of multiple auroral current sheets and theories of auroral arc multiplicity are briefly discussed. It is suggested that multiple X-lines in the distant tail, and/or leakage of energetic particles and FA currents from a series of plasmoids formed during preceding magnetic activity, could be one cause of highly stratified upward FA currents at the polar edge of the quieting double auroral oval.  相似文献   

17.
The suggestion that the polar cap can completely disappear under certain northward IMF conditions is still controversial. We know that the size of the polar cap is strongly controlled by the interplanetary magnetic field (IMF). Under a southward IMF, the polar cap is usually large and filled with weak diffuse polar rain electrons. The polar cap shrinks under a northward IMF. Here we use the global auroral images and coincident particle measurements on May 15, 2005 to show that the discrete arcs (due to precipitation of both electrons and ions) expanded from the dayside oval to the nightside oval and filled the whole polar ionosphere after a long (8 h) and strong (～5–30 nT) northward IMF Bz, The observations suggested that the polar cap disappeared under a closed magnetosphere.  相似文献   

18.
The Solar Magnetic Cloud (SMC)/Coronal Mass Ejection (CME) event of January1997 triggered auroral displays in all sectors of the auroral oval as well as in the polar cap region.Near infrared emissions from these auroras were recorded simultaneously in the night sector overSondrestromfjord (Sonde), Greenland, in the day sector over Longyearbyen, Svalbard and in thepolar cap region over Eureka, Canada. The spectral distributions of these emissions indicateprecipitation of electrons with average energy (EAV) of (500±100) eV,dissipating most of their energy around (180±20) km height (hmax) in thethermosphere. These findings are consistent with the concurrent auroral ionization profilesrecorded by the Incoherent Scatter Radar soundings at Sonde. In contrast, most of the nighttimeauroras, not related to SMC/CME events, are excited by electrons with EAV > a few keV and peak in the lower thermosphere with hmax around 110 km.Similarly, normal dayside cusp auroras and polar cap drizzle excited emissions emanate from theupper thermosphere above 200 km altitude. SMC/CME related auroras were also observed inOctober 1995 at Sonde, and in May 1996 as well as in May 1997 at the South Pole Station inAntarctica. Spectral characteristics, and hence EAV and hmax, of all these other SMC/CME related auroras, are similar to those of the January 1997event. These observations suggest that during a significant part of the period when SMC/CMEplasmas and fields interact with the magnetosphere, relatively low energy electrons precipitate inthe thermosphere. Such SMC/CME triggered auroras interact with the middle thermosphereconstituents in the 160–200 km height region. The latter region is inaccessible for remote sensingits composition and thermodynamics in normal auroras, which generally peak at lower heights; theSMC/CME events provide the opportunity for such investigations.  相似文献   

19.
A search for Pc3–4 wave activity was performed using data from a trans-Antarctic profile of search-coil magnetometers extending from the auroral zone through cusp latitudes and deep into the polar cap. Pc3–4 pulsations were found to be a ubiquitous element of ULF wave activity in all these regions. The diurnal variations of Pc3 and Pc4 pulsations at different latitudes have been statistically examined using discrimination between wave packets (pulsations) and noise. Daily variations of the Pc3–4 wave power differ for the stations at the polar cap, cusp, and auroral latitudes, which suggests the occurrence of several channels of propagation of upstream wave energy to the ground: via the equatorial magnetosphere, cusp, and lobe/mantle. An additional maximum of Pc3 pulsations during early-morning hours in the polar cap has been detected. This maximum, possibly, is due to the proximity of the geomagnetic field lines at these hours to the exterior cusp. The statistical relation between the occurrence of Pc3–4 pulsations and interplanetary parameters has been examined by analyzing normalized distributions of wave occurrence probability. The dependences of the occurrence probability of Pc3–4 pulsations on the IMF and solar wind parameters are nearly the same at all latitudes, but remarkably different for the Pc3 and Pc4 bands. We conclude that the mechanisms of high-latitude Pc3 and Pc4 pulsations are different: Pc3 waves are generated in the foreshock upstream of the quasi-parallel bow shock, whereas the source of the Pc4 activity is related to magnetospheric activity. Hourly Pc3 power has been found to be strongly dependent on the season: the power ratio between the polar summer and winter seasons is 8. The effect of substantial suppression of the Pc3 amplitudes during the polar night is reasonably well explained by the features of Alfven wave transmission through the ionosphere. Spectral analysis of the daily energy of Pc3 and Pc4 pulsations in the polar cap revealed the occurrence of several periodicities. Periodic modulations with periods 26, 13 and 8–9 days are caused by similar periodicities in the solar wind and IMF parameters, whereas the 18-day periodicity, observed during the polar winter only, is caused, probably, by modulation of the ionospheric conductance by atmospheric planetary waves. The occurrence of the narrow-band Pc3 waves in the polar cap is a challenge to modelers, because so far no band-pass filtering mechanism on open field lines has been identified.  相似文献   

20.
极盖等离子体云块是极区电离层常见特征之一,其形成演化过程是当前重要研究课题.光电离高密度等离子体在对流输送作用下从日侧穿过极隙,通过极盖到达夜侧,已成为共识.日侧磁场重联作用下的极区对流输运过程,在舌状等离子体结构（TOI）"断裂"形成极盖等离子体云块中发挥重要作用.利用极区全域GPS/TEC观测数据,结合SuperDARN雷达实测的对流速度,对等离子体云块形成过程进行案例研究,重点分析两种TOI断裂形成等离子体云块的发生机制.研究结果显示,等离子体对流输运过程在TOI断裂形成等离子体云块过程中发挥关键性作用,对流形态或局部对流速度矢量急剧变化都可能导致TOI结构不稳定,使TOI结构断裂形成等离子体云块.  相似文献   

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