Showing papers in "Journal of Atmospheric and Solar-Terrestrial Physics in 1990"

TL;DR: In this paper, the authors proposed that dust formed at the cool summer mesopause may have optical properties very different from that measured for bulk material of ice, and that smallness of the dust and possible surface impurities may lead to high photoelectric yields and low work functions.

TL;DR: In this article, the spectral resonance structure (SRS), excited by lightning, is proved experimentally by the SRS, which manifests itself as pronounced minima and maxima in the averaged spectral intensity of atmospheric background noise of a few hertz.

TL;DR: In this paper, sudden sodium layers (SSLs) are observed with a lidar instrument at Andenes, Norway (69°N) and their appearance shows a strong, positive correlation with that of ƒ-type Es layers.

TL;DR: In this article, an isotropic, spherically symmetric two-scale-height ionosphere's transverse magnetic mode eigenfrequencies, as well as the height and angular profiles of its electric and magnetic fields, are presently addressed by an approximate solution.

TL;DR: In this paper, a model of global atmospheric electric circuit has been developed, which incorporates the pollution due to aerosol particles of anthropogenic and volcanic origins and the ionization caused by the coronal discharges due to intense electric field beneath thunderclouds in the atmospheric layers close to the earth's surface.

TL;DR: In this paper, evidence is given for a secular change now taking place in the frequency of occurrence of noctilucent clouds, leading to the strong supposition that this change occurs as the result of a small, systematic cooling of the upper mesosphere in summertime.

TL;DR: In this paper, the authors show that the observed elevations of electron temperatures are created by very intense electric fields which can be found within narrow regions adjacent to auroral arcs, and discuss their observations against the background of models for electric field suppression or enhancement in the vicinity of auroral precipitation.

TL;DR: In this paper, the EISCAT VHF radar during the MAC/SINE campaign was used to study the polar mesosphere summer echoes (PMSE), which were studied with a high spectral resolution program.

TL;DR: In this article, the authors present a simple numerical model which ignores chemical effects in which a train containing a mixture of equal numbers of Fe + and Mg + ions is allowed to diffuse.

TL;DR: The progress in the study of ULF waves in the Earth's magnetosphere made between 1987 and 1989 is reviewed in this article, which includes satellite and ground-based observations of the ULF wave spatial structure, wave resonators and waveguides in the magnetosphere and ionosphere.

TL;DR: In this article, the authors used the servo model of Rishbeth et al. to calculate the peak height of the F2 layer, hmF2, and compared the results with observed values at noon and midnight derived from ionosonde measurements at two mid-latitude stations.

TL;DR: In this paper, two radars respectively operating at 53.5 MHz and 224 MHz have been used to simultaneously measure the polar mesospheric summer echoes (PMSEs) during the launch of a sounding rocket designed to measure the fluctuations in the electron density in the same height range.

TL;DR: In this article, a comparison of radar and rocket observations of electron density fluctuations and simultaneous 53.5 MHz radar measurements were made during the MAC/SINE campaign in northern Norway in summer 1987.

TL;DR: In this paper, the authors investigated the dependence of the ionospheric response on the time of occurrence of sudden commencement (SC) and the intensity of the magnetic storms for a low and a mid-latitude station by considering total electron content and peak electron density data for more than 60 SC-type geomagnetic storms.

TL;DR: In this article, the characteristics of polar mesosphere summer echoes (PMSE) are studied at 53.5 and 224 MHz, respectively, and the implications of these characteristics for several possible scattering mechanisms are discussed.

TL;DR: In this paper, the results of high-resolution observations of the vertical velocity field obtained with the EISCAT and SOUSY VHF radars near the high-latitude summer mesopause during the MAC/SINE campaign in northern Norway in 1987 are presented.

TL;DR: In this paper, the authors present results from 54 nights of simultaneous measurements, performed between 1984 and 1987, of rotational temperatures for the OH(6−2) and O2(1∑)(0−l) bands are presented.

TL;DR: In this article, two field campaigns were conducted, primarily in northern Norway, in the summer and late autumn of 1987; these yielded a total of 41 in situ temperature profiles and 67 in situ wind profiles.

TL;DR: For example, during the first LTCS (Lower Thermosphere Coupling Study) Campaign, 21-25 September 1987, the mean winds were globally westerly, consistent with early winter-like (NH) and late winter (SH) circulations as discussed by the authors.

TL;DR: In this paper, a special analysis technique for incoherent scatter measurements is introduced, based on the ion energy equation, which is used to fix this parameter in a second analysis and to allow the ion composition to be a free parameter.

TL;DR: The characteristics of the quasi-two-day wave, as observed in meteor wind data recorded at Grahamstown (33°19′S, 26°30′E) between April 1986 and April 1989, are described and discussed in the context of existing knowledge as mentioned in this paper.

TL;DR: In this article, the geomagnetic field variation and equivalent current system produced by an asymmetrical ionospheric dynamo action under a solstitial condition are simulated and compared with the observational results.

TL;DR: In this paper, two auroral zone electron precipitation events in the morning sector have been studied in detail using the UHF incoherent scatter radar in northern Scandinavia, and the electron density profiles are interpreted in terms of the incoming spectrum of energetic electrons, and it is shown that the spectrum is most energetic at the maximum of the event and softens subsequently.

TL;DR: In this article, the level of turbulence activity in the middle atmosphere observed during the MAC/EPSILON campaign using different in-situ techniques was determined using spectra of density fluctuations covering height intervals of typically 8 km.

TL;DR: In this article, the EISCAT UHF radar measurements of both electron density and field-aligned ion velocity show that an upward propagating gravity wave with a period of about 1 h is present.

TL;DR: In this article, matched filtering with 10 Hz frequency resolution was used for the analysis of the whistler waveform and the resulting high resolution dynamic spectrum was used to reveal the fine structure of whistlers.

TL;DR: In this article, a lifting of partially reflecting or scattering layers, which are distorted by bumps, is suggested as a possible cause of the Doppler frequency jumps in polar mesosphere summer echoes.

TL;DR: Sodium lidar measurements have been performed during three summer seasons at a polar latitude (69°N), yielding profiles of sodium number density and temperature of the 85-100 km altitude region as mentioned in this paper.

TL;DR: In this paper, a statistical correlation study is performed on two upper mesospheric temperature data sets for the region around 90 km, on the phase of the quasi-biennial oscillation (QBO) and on the solar 10.7-cm radiation.

TL;DR: In this article, the aerodynamic behavior of foil chaff (rectangular plates) used for in-situ measurements of atmospheric motions in the middle atmosphere (up to 100 km altitude) can be described by Stokes' Law in which the corrections are applied to the coefficient of viscosity.