Showing papers in "Journal of Atmospheric and Solar-Terrestrial Physics in 1993"

TL;DR: The EISCAT ionospheric modification (heating) facility at Ramfjordmoen will become a part of the IEEE 802.11 association from January 1993 as discussed by the authors.

TL;DR: In this article, the authors used measured field strengths from VLF transmitters to determine improved day-time values of ionospheric parameters to enable improved VlF propagation predictions.

TL;DR: The European Incoherent Scatter Scientific Radar System (EISCAT) as discussed by the authors is an EISCAT-based radar system that has been used for the first ten years of its operation.

TL;DR: In this paper, results of a General Circulation Model simulation of the dynamics of the middle atmosphere are shown focusing on the tidal wave mean flow interaction and propagation of migrating diurnal and semidiurnal tides in the model.

TL;DR: Sporadic Na (Na) layer events were frequently identified during 160 h of lidar observations at Arecibo in January, March and April 1989 as discussed by the authors. Most were accompanied by sporadic E ( E ) layers.

TL;DR: In this paper, the authors compare the performance of MF/HF partial-reflecton radar systems with those of a meteor-wind radar at heights of 80-100 km and a Fabry-Perot interferometer measuring 0(1S) emissions near a height of 97 km.

TL;DR: In this paper, seasonal variations in winds measured in the equatorial mesosphere and lower thermosphere are discussed, and oscillations in zonal winds in the 3-10 day period range are examined.

TL;DR: The AIDA-89 campaign has yielded the most comprehensive set of low-latitude incoherent scatter radar power profiles and derived electron concentration results ever made as mentioned in this paper, which have been used to study the time-height trajectories of 80-150 km ion layers and serve to gauge both the periodicity and variability of ion layer structure throughout the campaign.

TL;DR: In this paper, the authors examined 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 diplatitude.

TL;DR: In this paper, it was pointed out that this wave trapping concept implies a prediction that the effect should be suppressed when the frequency of the HF transmitter is slightly below a harmonic of the electron gyro frequency.

TL;DR: In this article, the authors presented results of joint heating/incoherent scatter observations at Tromso and found that most of the observed features are in good agreement with the PDI theory, while some others remain still unexplained.

TL;DR: In this paper, the Lomb-Scargle method was used for unevenly spaced data to estimate the horizontal characteristics of 14 gravity waves, two evanescent and 12 internal, from 12-direction simultaneous measurements of the O 2 ( 1 Σ) (0-1) airglow observations of a ground-based instrument, MORTI, during AIDA '89.

TL;DR: In this article, an ion-ion two-stream instability is suggested to be the cause of the observed enhanced ion-acoustic fluctuations, which will give a greatly enhanced Joule heating in the presence of field-aligned currents because of the resulting anomalous resistivity by turbulently fluctuating electric fields.

TL;DR: In this article, the authors used Rayleigh/Na lidar data to calculate the relative atmospheric density perturbations and their spectra and found that the observed altitude variations in m-spectra magnitudes are inconsistent with linear instability theory which predicts that density spectra in the saturation regime vary only as N 4 m 3.

TL;DR: In this article, the day-to-day variations of noon F2-layer height and Elayer electron density at three ionosonde stations (Slough, Port Stanley and Huancayo) were found to be well correlated with the day to day variations of solar activity.

TL;DR: In this article, the authors analyzed radar data from 1979 to 1990 to investigate the solar activity effects on upper middle atmospheric winds and tidal amplitudes and found that the observed features are fairly consistent with the early results reported by Sprenger and Schmindkr [(1969) J. atmos. terr. Phy. 31, 217).

TL;DR: In this article, the electrodynamics of a pre-midnight auroral arc, situated close to the equatorward border of the convection reversal, are studied by ground-based measurements.

TL;DR: In this article, the authors used low-altitude satellite data and sounding rocket measurements to characterize the location and strength of the relativistic electron precipitation into the atmosphere and concluded that the magnetospheric electrons, when dumped into the middle atmosphere, represent a very significant ionization source which affects the pattern of conductivity, electric fields, and atmospheric chemistry.

TL;DR: A brief review of the development of models of the ionospheric conductivities with special emphasis on high latitude regions and the auroral zone is presented in this article, where a superior technique in resolving electron density profiles of high time and height resolution by incoherent scatter radars on the ground is presented.

TL;DR: In this paper, the authors investigated the semidiurnal tidal dynamics of the Antarctic and Arctic mesopause regions (95 ± 15 km) through comparative analyses of monthly mean tidal wind fields determined from radar measurements at the Scott Base (78°S), Molodezhnaya (68°S) stations in the Antarctic, and the near-conjugate stations of Heiss I. (81°N) and Poker Flat (65°) in the Arctic region.

TL;DR: In particular, the time-height trajectories of middle and upper E region Tidal Ion Layers (TILs) for early January 1989 closely resemble those from early January 1981, which first revealed the presence of a 6-h quasi-periodic intermediate layer structure.

TL;DR: In this paper, the authors investigated the dynamics of the Antarctic and Arctic mesopause regions (ca. 95 ± 15 km) through comparative analyses of winds measured by radars at the Scott Base (78°S), Molodezhnaya (68°S) stations in the Antarctic, and the near-conjugate stations of Heiss I. (81°N) and Poker Flat (65°N).

TL;DR: In this paper, the effects of electric fields, interhemispheric fluxes and neutral winds on the ionosphere were calculated using a full-time-varying model.

TL;DR: In this article, the authors examined the influence of temperature fluctuations on the formation of sporadic sodium layers (SSLs) with particular emphasis on AIDA (Arecibo Initiative in the Dynamics of the Atmosphere) results.

TL;DR: In this paper, a new parameterization of the 15 μm CO 2 band radiative cooling rate in the middle Earth atmosphere for both LTE (local thermodynamic equilibrium) and non-LTE layers is presented.

TL;DR: In this paper, it was shown that the amplitude of the auroral electric field was proportional to the r.m.s. amplitude associated with the gravity-wave, and the time lag between the onset of strong auroral activity and the arrival of the travelling disturbance over the U.K. was usually about an hour, suggesting a source region about 2000 km north.

TL;DR: In this paper, the dependence of η, the ratio of emission rate fluctuation to temperature fluctuation, on the gravity wave parameters and chemical parameters is developed using a model for the O2 airglow's response to a gravity wave.

TL;DR: In this paper, an attempt is made to reconcile two competing views as to where the auroral distribution maps from in the magnetosphere, and the structure of the aurora is shown to have two distinctive parts which vary according to the magnetic activity.

TL;DR: The ionospheric location of substorm onset is generally found to be at the most equatorward arc in the poleward portion of the diffuse aurora as mentioned in this paper, which provides a reference from which the source region in the magnetotail may be assessed.