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Results of two extensive rocket campaigns, the NASA E-region Radar and Rocket Instability Study (ERRRIS) and Rocket and Scatter Experiments (ROSE), are reviewed. Particular attention is given to scientific objectives and first results of the ROSE project, plasma waves observed in the auroral E-region during the ROSE compaign, metal ion layers in the auroral lower E-region measured by mass spectrometers, EISCAT results during the ROSE campaign and a comparison with STARE measurements, the effects of the resonance broadening of Farley-Buneman wave on electron dynamics and heating in the auroral E-region, and observations of 3 m auroral irregularities during the ERRRIS campaigns.

In the late winter of 1988 and 1989, three NASA sounding rockets were flown through the auroral electrojet from ESRANGE (Sweden) as part of the E-region Rocket-Radar Instability Study (ERRRIS). Many ground-based instruments supported these flights, including the EISCAT, STARE, and CUPRI radars, as well as all-sky cameras, riometers, and magnetometers. In this paper the observations of the Cornell University Portable Radar Interferometer (CUPRI), which detected coherent backscatter from 3-m irregularities in the auroral E-region are summarized. Twenty hours of power spectra and interferometry data are available, and, during the 1989 campaign, three weeks of nearly continuous Range-Time-Intensity (RTI) and first moment data were recorded.

In a previous paper, Fraser and Thorpe (1976) indicated that the average partial-coherence spectra for three summers and the average for three winters at a southern mid-latitude site had a dominant peak at a period of about six days. This peak in coherence between absorption and temperature is anomalous, and the present paper explains how some of the unexpected coherence features can be explained by the five-day wave described by Geisler and Dickinson (1976) and whose existence in the upper stratosphere was discussed by Rodgers (1976).

A large number of ground based, balloon and rocket borne experiments was performed at various stations during DYnamics Adapted Network for the Atmosphere (DYANA). This allows the comparisons of simultaneous wind profiles determined by different techniques. This paper briefly describes each technique and discusses the comparisons between: (1) foil chaff at Andoya (69 deg N, 16 deg E) and EISCAT winds data at Tromso (70 deg N, 19 deg E); (2) foil chaff or falling sphere at Andoya and MF radar winds data at Tromso; (3) MF radar at Juliusruh (54 deg N, 13 deg E), meteorological radar at Kuehlungsborn (54 deg N, 11 deg E), meteorological rockets at Zingst (54 deg N, 12.5 deg E) and LF drift winds at Collm (51.3 deg N, 13 deg E); (4) falling sphere, balloons and, for the first time, a Rayleigh Doppler Lidar at the Centre d'Essais des Landes (C.E.L. 44 deg N, 1 deg W). These methods have widely varying altitude, spatial and temporal resolutions. Despite these differences, the comparisons show a generally good agreement.

The interaction of the Earth's magnetosphere with the solar wind and northward interplanetary magnetic field (IMF) continues to raise scientific interest and controversy. A selected group of papers from a conference on this topic discuss the following subjects: electric field generation, theoretical models of polar-cap convection, polar-cap distributions, dependencies of the polar-cap auroral distribution, and boundary populations in the polar-caps. Also discussed are satellite observations of polar arcs and mapping of the ionospheric convection response.

In view of the disagreement between reports of Langel and Estes (1985) and those of other investigators using Nagsat data sets, concerning the evidence for equatorial electrojet and meridional currents in the dawn Magsat data, this paper reexamines the Magsat data for the presence of equatorial electrojet and meridional current in both dawn and dusk local times, using a specially designed method for isolating field variations organized by dip-latitude. It is shown that such fields, if any, at dawn are very weak and do not result in a persistent pattern from longitude to longitude or a pattern consistent with that expected from an electrojet current. On the other hand, fields organized by dip-latitude are clearly present in the dusk data and it is possible to isolate longitudinal and seasonal variations in such fields. Current densities are computed for both the equatorial electrojet and meridional currents and are compared to the current densities and distributions found with recent models of the ionospheric dynamo and equatorial electrojet.

The transport of mass, momentum, energy and waves from the solar wind to the Earth's magnetosphere takes place in the magnetopause-boundary layer region. Various plasma processes that may occur in this region have been proposed and studied. In this paper, we present a brief review of the plasma processes in the dayside magnetopause-boundary layer. These processes include (1) flux transfer events at the dayside magnetopause, (2) formation of plasma vortices in the low-latitude boundary layer by the Kelvin-Helmholtz instability and coupling to the polar ionosphere, (3) the response of the magnetopause to the solar wind dynamic pressure pulses, and (4) the impulsive penetration of solar wind plasma filaments through the dayside magnetopause into the magnetospheric boundary layer. Through the coupling of the magnetopause-boundary layer to the polar ionosphere, those above processes may lead to occurrence of magnetic impulse events observed in the high-latitude stations.

The plasma instabilities in the low-attitude auroral ionosphere and the sources of free energy that drive these waves have been examined in detail in the framework of the ERRRIS project. Independent sets of experiments were carried out on board three NASA sounding rockets which were flown in conjunction with radar backscatter measurements from Esrange, Sweden, in 1988 and 1989. The backscatter measurements were taken by the 50 MHz CUPRI system for determining the launch conditions. The Eiscat incoherent scatter radar was used to take plasma drift, density, and temperature measurements on board two of the flown rockets. STARE observations of 1 m backscatter echoes were also made. The STARE velocity fields were in agreement with the Eiscat and in situ measured electric fields. Both CUPRI and STARE observed a very dynamic and changing auroral ionosphere over Esrange. It is concluded that the ERRRIS experiments provided valuable data on plasma instabilities in the auroral electrojet, including detailed in situ measurements of the two-stream wave spectrum and phase velocities.

This paper presents two case studies of the large-scale nightside ionospheric plasma convection observed in the two polar regions utilizing HF backscatter radars. The times at which the nightside flow reversal (the Harang discontinuity) occurs is seen to differ by several hours between the two study periods and between the two hemispheres. Flow reversal appeared simply to be shifted to later magnetic times in the Southern Hemisphere, while the evening westward flow was disrupted by the occurrence of eastward flow ahead of the Harang discontinuity in the Northern Hemisphere.

Lightning-produced electromagnetic effects may produce significant modifications in the ionospheric plasmas. An outstanding phenomenon investigated in this paper is the so-called explosive spread F, whose close link with lightning has been identified (Woodman and Kudeki, 1984). Parametric instability excited by the lightning-induced whistler waves is proposed as a potential source mechanism causing the explosive spread F.

Elliptical polarization and mode splitting have been detected in the magnetic component of discrete, well defined Schumann resonance excitations. These ELF excitations, which are large electromagnetic transients of approximately 1 s duration, are called Q-bursts and typically occur every few minutes. They are believed to be the signature of the impulsive excitation of the earth-ionosphere cavity by ultra-large lightning currents. In this paper the magnetic polarization and spectral characteristics of four large Q-bursts are examined in detail using a new analysis technique. Two events display right-hand polarization and two display left-hand polarization. The theoretical polarization properties of the central and side multiplets of the Schumann resonances are used to define a local orthogonal coordinate system in the measurement frame in which these components may be separated. Maximum entropy spectrums computed separately for what are identified to be the central and side multiplets in this coordinate system show distinctly different eigenfrequencies for the lowest mode near 7.5 Hz. For the limited number of cases examined the magnitude of the line splitting detected using this technique is roughly 1.4-1.8 Hz, larger by nearly a factor of two than theoretical or observed values of the splitting previously reported. The frequencies of the side multiplets may lie either above or below the frequency of the central multiplet.

Accurate measurement of the electron density profile and its variations is crucial to further progress in understanding the physics of the disturbed equatorial ionosphere. To accomplish this, a plasma frequency probe was included in the payload complement of two rockets flown during the Condor rocket campaign conducted from Peru in March 1983. This paper presents density profiles of the disturbed equatorial ionosphere from a night-time flight in which spread-F conditions were present and from a day-time flight during strong electrojet conditions. Results from both flights are in excellent agreement with simultaneous radar data in that the regions of highly disturbed plasma coincide with the radar signatures. The spread-F rocket penetrated a topside depletion during both the upleg and downleg. The electrojet measurements showed a profile peaking at 1.3 x 10 to the 5th per cu cm at 106 km, with large scale fluctuations having amplitudes of roughly 10 percent seen only in the upward gradient in electron density. This is in agreement with plasma instability theory. It is further shown that simultaneous measurements by fixed-bias Langmuir probes, when normalized at a single point to the altitude profile of electron density, are inadequate to correctly parameterize the observed enhancements and depletions.

The motion of the thermosphere with a rotational velocity between 10 and 20 per cent in excess of the earth's rotational velocity has been deduced by King-Hele and his co-workers from the change of the inclination of satellite orbits. To date, no completely satisfactory explanation of the observations has been presented. In this paper, it is shown that in the thermosphere there exists a small diurnal mean driving force in the eastward direction. This force has not previously been considered in analyses of superrotation. A critical review of the observations and a theoretical analysis that takes account of both equinox and solstice conditions is presented. In the lower height region, where the great majority of observations were made, it is possible to achieve agreement between observations and a dynamical model. Additional observational data are needed in the isothermal region for a more complete analysis.

At ionospheric heights, the geomagnetic field is virtually incompressible. In consequence, an electromagnetic drift can only compress the F-region plasma by moving it in a direction in which the field becomes stronger. This paper examines the rate of compression at mid-latitudes for three different assumptions about the ion motion.

The paper identifies global zones of energetic particle precipitation in the nighttime atmosphere during disturbed magnetic conditions in rocket, satellite, and ground-based measurements. The known equatorial zone of precipitated energetic ions and neutrals is found at altitudes above 170 km, with its origin in the double-charge-exchange process of hydrogen and helium with the ring current. The flux of electrons increases linearly with altitude in the region 100-300 km and correlates with the 391.4 nm radiation intensity and magnetic activity. Finally, it is shown that the South Atlantic magnetic anomaly provides additional support for the identification of distinct low and mid-latitude zones; poleward from the plasmapause the precipitation flux is nearly isotropic and variable, and it consists of electrons and ions with the maximum intensity of the proton auroral zone occurring about 5 deg equatorward of the maximum of the electron auroral zone.

The paper discusses some phenomena, mainly observed by satellites, which illustrate the use of helium as a tracer for studying the morphology and history of atmospheric responses to energy inputs of varying amplitudes and durations. The effects observed include (1) the annual north-south excursion of the sub-solar point producing the winter helium bulge, (2) the 24-hour diurnal variation, where the helium density peak is phase-shifted to the morning in the lower thermosphere, (3) high latitude magnetospheric heating of the thermosphere, with helium indicating regions of probable upwelling of the heated gas, and (4) gravity wave formation and propagation, with the attendant implications for transport of energy from one region of the atmosphere to another.

A combination of phase-path length difference and Faraday rotation angle data obtained from geostationary satellite transmissions is used to determine the integration constant necessary to convert phase-path length difference information into absolute values of total slant columnar electron content. The total content thus determined, which is the sum of the ionospheric and protonospheric contents, is measured with uncertainties about one order of magnitude smaller than the value of the protonospheric content. It is thus, in principle, possible to determine the latter by subtracting from the measurement the so-called 'Faraday content.' This idea, proposed by several authors in the past, is critically examined in the present paper. It is impossible to totally eliminate the ionospheric contribution to the measurements; however, it is shown that the degree of elimination depends on the type of distribution of the longitudinal component of the geomagnetic field along the path of observation. Satisfactory minimization of the ionospheric contribution can be accomplished only under certain geometries of observation.