Two rockets, SISSI (Spectroscopic Infrared Structure Signatures Investigation) F2 and F3, were launched during summer twilight conditions at ESRANGE, Kiruna, Sweden in July and August 1990. The payloads contained, in addition to other experiments, an infrared radiometer for the measurement of the OH Meinel (3-1) band and O₂ (¹(Delta) _g) emissions and a resonance fluorescence experiment for the measurement of [O]. SISSI F2 was launched during a fading noctilucent cloud event and F3 during a solar proton event. For both rocket flights and for rocket ascent and rocket descent, an unexpected enhancement of the emission monitored by the OH radiometer was observed above 90 km. The glow was not detected by the O₂ radiometer, was spin modulated, and was different in intensity for the two flights. Atomic oxygen concentration altitude profiles for F2 and F3 were different in peak concentration and in shape and exhibited a spin modulation that correlated with the glow spin modulation. We use these unique data sets with steady-state equations to model and investigate the odd-oxygen concentrations in the polar mesosphere during summer twilight conditions.

Main specifications of new optical design for monochromatic auroral imaging is presented. It differs from that developed earlier by relatively low F number (F/2.0), small dimensions (589 mm long), and large image size (35 mm) with flat focal surface (32 mm focal length), and is intended to work with modern types of light receivers. It can be used both at ground and space observations.

Determining the mechanism which produces poleward-moving auroral forms (PMAFs) is a very controversial topic. Satellites have recorded flux erosion at the dayside magnetopause. Some studies have shown possible connections between PMAFs and flux transfer at the dayside magnetopause. More evidence is needed before poleward-moving auroral forms can be linked to the flux transfer events seen by satellites. This paper presents some new results from a statistical study on PMAFs. This statistical study has identified 476 PMAFs from twelve years of ground-based optical data. From this data base a time distribution between successive PMAF events is presented. The mean time found between successive PMAF events is 6 minutes. A comparison between the distribution of inter-FTEs intervals at the magnetopause found by Lockwood and Wild and the intervals between PMAF events in the ionosphere is shown. This correlation may provide more evidence for linking PMAFs to flux transfer at the magnetopause.

Optical observations at Barensburg and Hiss Is. during periods of magnetic impulse events are examined. Fifty-three percent of magnetic impulses are shown to be accompanied by pronounced auroral signatures. The equatorward 1 degree(s) - 2 degree(s) latitude displacement of the dayside red auroral band and simultaneous increasing of its intensity were observed for about 5 - 10 min before the magnetic impulses. During the magnetic events two rayed auroral forms appeared usually in the equatorward part of the red band. At first the discrete aurorae moved toward the pole and then generally to the west (tailward) and disappeared in 4 - 8 min. The equatorial boundary of the red luminosity band was back to its pre-event position in 20 - 30 min. The structure and dynamics of a few ionosphere current systems caused magnetic impulses were investigated with the high latitude network of magnetometer. Ionospheric currents had a twin vortices structure with the cells separated in the west-east direction.

The morphology of the dayside auroral activity at high latitudes is discussed on the basis of photometers and low light TV camera observations. Review of the results of different groups of researchers are presented. The auroral activity observed is classified into two event types: (1) Drifting Ray Structures (DRS) and (2) Pulsating Aurora. The connection is discussed between these two events and precipitation particle fluxes of the different magnetospheric regions.

A simple procedure to evaluate the Balmer excitation rates of H_(alpha ) and H_(beta ) to produce the corresponding volume emission rates vs. height, using semi-empirical range relations of protons in air, is used. The calculations are carried out with identified ion-energy particle spectra of the dayside aurora obtained by low altitude satellites. It is found that the calculated emission intensities of H_(alpha ) and H_(beta ) are observable for ground-based optical detection. Measurements of the dayside aurora at Longyearbyen, Svalbard, are discussed in relation to these calculations. Furthermore, it is observed pulsed proton events on the dayside which have decreasing time between each event show increase in the emission intensity and a fluctuating behavior in the primary initial proton energy. Each pulsed proton event was associated with an enhancement in the green 5577 angstrom emission, and some corresponded to poleward-moving auroral forms.

The volume emission rates of auroral proton/hydrogen particles in the upper atmosphere is derived using laboratory coefficients for energy degradation and emission cross sections. Doppler broadened Balmer emissions are measured with the field of view of the spectrometer in the geomagnetic meridian plane, and indications of energy and pitch-angle distributions are obtained by fitting the expressions of the calculated Doppler profiles to the measured profiles. Using a limited amount of data and comparing with the model calculations indicate that the energy spectra of the auroral protons are relatively soft at 74 degree(s) geomagnetic north, and have a broad and variable pitch-angle distribution.

In this paper we present some results for the Monte-Carlo transport model of auroral electron and proton-hydrogen atom precipitations. Using the `collision-by-collision' degradation scheme we could consider an influence of the dipolar geomagnetic field on the main transport characteristics in detail. For electron and proton fluxes we find that: (1) the model gives a good agreement with the laboratory transport measurements of the energy deposition distributions, ranges, albedo, lateral spreading and `effective eV per electron-ion pair;' (2) the shape of the altitude energy deposition distribution depends on dipolar geomagnetic field insignificantly, but albedo changes very strongly; (3) the main features of the electron flux spectra in the whole energy and pitch-angle ranges, including `break' of the flux curve near 20 - 30 eV, are described by our model rather well; (4) the lateral spreading of the proton fluxes depends greatly on the initial energy and the altitude; (5) the energy-dependent behavior of the `eV per electron-ion pair' for electron and proton fluxes has a similar shape and is nearly constant (approximately equals 35 eV) as initial energy of particle increases.

A model of interaction of energetic electrons with the upper atmosphere is proposed. Electron energy distribution function is found by the solution of kinetic equation assuming continuous energy losses for the electrons of primary flux. On the basis of the proposed model the calculation of number of the direct excitations of molecular nitrogen is performed. Estimated luminosity height profile of 3914 angstrom band is compared with experimental rocket ones.

The telecentric optical system (TOS) is the optical system intended for monochromatic observations of luminous objects of large extent. At present several versions of the system are known. We offer the one developed in PGI. It has essential advantage concluding in its smaller sizes and weight. TOS can be used with different types of receivers and applied in various fields of atmospheric optics. The optical scheme proposed below differs from others and has higher relative aperture and less number of elements.

Magnetometer and riometer data from the Kara sea meridian stations, VIKING image data, and DMSP F7 spacecraft particle detectors data for substorms on April 5, and 9, 1986 have been used to examine relation of filamentary structure of the westward electrojet to auroral absorption, aurorae, and ionospheric conductivity in the midnight auroral zone. Good correspondence between all these phenomena has been established.

The construction of the portable high sensitivity spectrograph is described. The spectrograph technical possibilities and results of the test observations of aurora and airglow are discussed. The portable digital spectrograph is designed for the simultaneous recording of a spectrum of low intensity sources in a wide range of wavelengths (all visible diapason and nearest UV and IR). The device consists of two functional parts: (1) the spectral optical block (the different portable spectrographs having various spectral coverage, spectral resolutions, dispersions, apertures, and optical transmissions); and (2) the multichannel photoelectric recording system.

The excitation mechanisms of 5577 angstrom auroral green line are studied using data from in situ rocket measurements by Sharp et al. and Deans and Chepherd. For the satisfactory agreement between modelled 5577 angstrom luminosity profiles and observed profiles during two experiments the rate coefficient of the quenching of O(¹S) by O has to be equal to 1 (DOT) 10^-11 exp(-680/T). Energy-dependent behavior of the column intensity ratio I5577 angstrom/I4278 angstrom is strongly varied with the season and can't be a good instrument for deducing initial electron flux parameters.

Latitudinal distributions of auroral emissions 656.3 nm (H_(alpha )) and 557.7 nm from Loparskaya are analyzed for (17-23) UT on January 30, 1979 when four substorm intensifications were observed. The electric field and electron precipitation (auroral x rays) were measured simultaneously by the balloon. It is shown that the large variations of the electric field were observed in the equatorward part of the auroral zone where most of the time the hydrogen emission occurred. The absence of the proton precipitation inside the WTS was also found.

An experiment with artificial proton aurora would be a new step of investigation of physical and chemical processes in ionosphere. The spatial distribution of the emission intensity in the zone of injection of p, H and H^- beams is discussed. The beam intensity that would be necessary for observation of the optical effects from the ground is estimated.

The results of experimental study of the local precipitations which associated with bursts of auroral patches and movement of auroral forms are discussed. The model of the field-aligned irregularities produced by auroral precipitation is developed for explanation of the amplitude and spectrum variations of the HF probe signal.

A large number of excellent far ultraviolet auroral images were obtained by the Canadian ultraviolet imager dual camera system on board the Swedish Viking satellite launched in 1986. The high spatial and temporal resolutions of the observations have been used very effectively in the continuing development of theories of auroral morphology. The images can also be used to infer approximate auroral energy deposition rates due to precipitating particles if the absolute sensitivities of the cameras are known. An in-flight calibration procedure is described in which ultraviolet stars are used as absolute radiation standards.

An observational program was designed to enhance the knowledge of the behavior of the proton auroral oval at mid-latitudes as a function of local time and global auroral activity for the purpose of determining the proton energy input rates into the atmosphere. Ground-based observations of H_(beta ) 4861 angstrom and N₂⁺ 4709 angstrom auroral emissions were made from Ottawa, Canada (45.2 degree(s) North, 283.7 degree(s) East) during most new moon periods from October 1977 to May 1981. Data were collected with a filter wheel photometer operated in the meridian scanning mode at a rate of about two scans per minute. Corrections for instrumental sensitivity and for atmospheric extinction and viewing angle were applied to the raw data. A subset of the final results was used in the current analysis to investigate the relationship between the brightness of the most intense mid-latitude proton aurora and auroral magnetic activity.

Solar zenith angle dependencies of OI and N₂⁺ emission brightness and analytical approximations of each emission brightness at 120 - 160 km altitudes for undisturbed atmosphere are obtained using the results of a series of MR-12 rocket experiments with the same type spectrophotometers. Results of the rocket measurements of daylit auroral brightness are presented. Features of altitude distributions of these emissions are shown and their differences from altitude distributions of brightness in undisturbed atmosphere dayglow and darktime auroras are given.

An analytical model of polar auroral oval has been developed. Comparison of the model with the experimental data has been carried out. The model was used to calculate IR radiation of the upper atmosphere in the polar oval region.

The calibration technique for measurements of extended luminous ionospheric objects brightness (aurorae, meteors, artificial ionospheric clouds) during TV filtering observations is proposed. The calibration curve energy scale of the method is based on extrafocal images of one bright star with known spectral energy distribution. Level series of illuminance of input photocathode is obtained by stepwise change of the extrafocal image diameter of star. The number of illuminance levels within the TV tube dynamics range is of 10 - 15. The error of each measured brightness value is about 10%.

In three barium releases made over the Caribbean during the summer of 1991, some peculiarities of the ion cloud dynamics and structure were observed with a low light level TV imager operated onboard a Russian research vessel. The two clouds were observed near the release region during the twilight following the initial release. One of the releases was made during evening twilight and the ion cloud reappeared the following morning. The other was a morning release and the late-time observations were made the next evening. The third ion cloud had unusual wave-like deformation of ion sheet surface. The wave structure of ion sheet surface was observed during 30 minutes. The potential long lifetime for more than 10 hours and small-scale deformations of the ion clouds will allow checks of ionospheric convection models and studies of ionosphere E-fields structure.