Fast tailward ion flows with strongly southward magnetic fields are frequently observed near the neutral sheet in premidnight sector of magnetotail at 20–30 R E for substorm onsets Geotail observations. These fast occasionally accompanied by a few keV electrons. With these events, we study structure and dynamics reconnection. The plasma reconnection site can be divided into three regions: region (near absolute magnitude B x < 5 nT), boundary sheet/tail lobe is or > 10 off‐equatorial...

The low energy particle (LEP) instrument onboard GEOTAIL is designed to make comprehensive observations of plasma and energetic electrons ions with fine temporal resolution in the terrestrial magnetosphere (mainly magnetotail) interplanetary medium. It consists three units sensors (LEP-EA, LEP-SW LEP-MS) a common electronics (LEP-E). Energy-per-charge Analyzers (EA) measure three-dimensional velocity distributions (with EA-e) EA-i), simultaneously separately, over the. energy-per-charge...

Magnetospheric convective system proposed by Axford and Hines is revised made compatible with the view, based on recently obtained geomagnetic data, that (1) motion induced solar wind would penetrate to innermost part of magnetosphere, if it were not for superposed effect earth's rotation, fact (2) magnetosphere has an essentially open tail. Magnetic lines force in are then found separated into two groups: those travel across tail during never transported On field former group, plasma...

A DP 2 fluctuation has a time scale of about one hour and appears coherently all over the world. It differs from polar substorm (DP 1) in that it is not caused by activation auroral electrojet. Its current system consists twin vortices zonal part. associated with fluctuations magnetospheric plasma convection, will provide useful means for identification ‘viscous-like’ interaction mechanism.

Plasmoids in the Earth's magnetotail were studied statistically, using low energy particle (LEP) and magnetic field (MGF) data from Geotail spacecraft. Their evolution along tail axis X GSM′ = −16 to −210 R E was investigated with 824 plasmoid events. dependence on Y as well derive three‐dimensional structure of plasmoids. (The coordinates are aberrated remove average effects orbital velocity Earth about Sun.) We defined a rotating fields enhanced total pressure. In near ( ≥ −50 ), there...

The magnetic structure of the magnetotail during expansion phase substorm is examined by summarizing observations made at more than fifty different locations scattered over (solar magnetospheric) range 0 ≳ x −65 RE, 20 y −20 and 30 |z| ≥ RE. It found that all across local-time sector |y| ≲ 15 neutral line formed somewhere between = −10 −30 RE within ∼10 min onset phase. This due to severe weakening or disruption tail current inside ≃ continues exist for about 1 hour, its disappearance occurs...

In former estimates of the ionospheric screening effect, a magnetic potential field or an electromagnetic wave has been employed to represent disturbance in neutral atmosphere. But characteristics number changes observed geomagnetic are inconsistent with these special representations. Hence estimate modification is repeated, using more general solution Maxwell's equations parameters chosen fit features. The result shows that incident by ionosphere depends not only on time scale phenomenon...

The thinning of the near‐Earth current sheet during growth phase CDAW 6 magnetospheric substorm is studied. expansion onset occurred at 1054 UT, March 22, 1979. During phase, two spacecraft, ISEE 1 and 2, were within approximately 13 R E from Earth obtained simultaneous high‐resolution magnetic data points in sheet. Plasma also provided by spacecraft solar wind IMP 8. To facilitate analysis, GSM field are transformed to a “neutral coordinate system” which new x axis parallel average above...

We consider consequences of the reconnection that occurs randomly on dayside magnetopause. Open field lines produced by such events often intersect with each other, and they do not necessarily show some features would be expected from if this mutual interaction were absent. Some open re‐reconnect result in closed lines. The solar wind plasma streams into magnetosphere along these as long are open, however, stays there after become again. propose is mechanism supply low‐latitude boundary...

In this introductory article to the GEOTAIL special section, spacecraft specifications, science instruments, data handling procedures, and orbit in first 1.5 year of operation are briefly described.

The structure of the plasma sheet in distant magnetotail observed by Geotail satellite is examined. We found that often different from standard Harris‐type [ Harris , 1962]. can be expressed as a double‐peaked current which has pair localized electric currents away neutral sheet, i.e., geometrically thick zero magnetic field region attached to thin boundary layer with large gradient. This type at radial distances −50 > X GSM / R E −125. discuss possible model explain formation terms...

The GEOTAIL magnetic field observations in the earth's magnetotail are examined terms of a turbulent reconnection process. It is found that observed Fourier power spectral density fields can be approximated by power‐law spectrum which changes its slope around turnover frequency with 0.04 Hz, spite differences among wide variety perturbations distant plasma sheet. data classified into two cases (Nishida et al. this issue): one accompanied plasmoid bipolar signature on B z field, and other...

Recent reports claim that the onset of expansion phase magnetospheric substorms is triggered by a sudden northward turning interplanetary magnetic field vector (IMF). We investigate this studying relation between onsets activity (AL index) and changes in IMF (rectified electric field). Specific examples solar wind demonstrate sharp AL occasionally appear to be independent wind, but more frequently they turnings. A statistical analysis for first six months 1978 shows auroral zone disturbance...

It is suggested that energetic particles populating the Jovian outer magnetosphere and neighboring interplanetary space are flowing out from radiation belt by outward diffusion process violates both second third adiabatic invariants. This cross-field operates preferentially at low altitudes, it does not cause serious degradation of particle energy. A model constructed which combines this with ordinary inward pitch angle scattering, found to compare favorably Pioneer 10 observations in magnetosphere.

Magnetotail electron observations by Vela satellites (at a radial distance of about 18 RE) and tail magnetic field Explorer 34 (when its is beyond 25 are combined. They support the belief, advanced earlier, that during substorms neutral line formed in near-tail region, earthward orbit, formation leads to rapid (further) thinning plasma sheet distance. The intervals with associated thin have duration 0.5 1 hour, they appear intermittently after energy storage magneto tail. In ground...

Solar wind-magnetosphere interaction modes from Explorer 33 and 35 interplanetary plasma magnetic field data

A distinctive magnetic structure in which azimuthal and latitudinal angles of field vectors are closely related to each other has been found the interplanetary data obtained by Sakigake at 0.8–1.0 AU. In this structure, termed a ”planar structure” (PMS), nearly parallel fixed plane. This plane includes spiral direction but is inclined ecliptic from 30° 85°. The take almost all directions PMS consists several segments constant, separated tangential discontinuities where directional changes...

We have identified slow‐mode shocks between the plasma sheet and lobe in midtail to distant‐tail regions by using three‐dimensional magnetic field data including density, velocity, temperature, heat flux of both ions electrons observed GEOTAIL satellite. Analyzing obtained September 14, 1993, February 16, 1994, we found 303 sheet‐lobe boundary crossings at distances ‐ X GSE ∼ −30 R E −210 . Thirty‐two out these boundaries are as shocks. back streaming on upstream side shocks, which may be...

A numerical model of the cosmic ray storm in two‐dimensional heliosphere is constructed incorporating drift effect. We estimate effect a flare‐associated interplanetary shock and disturbed region behind it (characterized by enhancement velocity magnetic field, decrease mean free path) on density anisotropy rays heliosphere. As disturbance propagates outward, appears front side, depression produced rear side. The most clearly higher‐latitude region. For parallel (antiparallel) state solar...