Showing papers in "Journal of Atmospheric and Solar-Terrestrial Physics in 1992"

TL;DR: In this article, the authors define the mid-latitude trough as the region of low plasma concentration at F-region altitudes that occurs near the equatorward side of the low latitude edge of the energetic electron precipitation boundary of the auroral oval.

TL;DR: In this paper, a new set of corrected geomagnetic coordinates (CGM) has been calculated from the magnetic field model DGRF for Epoch 1985 and the IGRF model for epoch 1990, which is based on the vertical projection on the Earth's surface of the B -minimum value point (apex) on each geOMagnetic field line.

TL;DR: In this article, the first experimental hints of a decrease of the peak height of the ionospheric F 2-layer were found, which qualitatively agree with the predictions of Rishbeth [(1990) Planet. 38, 945] who expected a lowering of the E - and F 2 -layer caused by a global cooling of the strato, meso- and thermosphere due to the increasing greenhouse effect.

TL;DR: In this paper, the authors investigated daily and seasonal variations of occurrence frequency of echoes from the irregularities, and found that the irregularity echoes were most frequently observed in June, near the summer solstice; they appeared in the periods after sunset and sunrise of the E-region, and the variance of the signal intensity was larger for the echoes in the post-sunset period than those in the pre-sunrise period.

TL;DR: In this paper, a preliminary experiment to test the application of computerized tomography (CT) to ionospheric imaging is described, in which radio transmissions from NNSS satellites were used to measure the total electron content required for the tomographic image of electron density.

TL;DR: In this article, the authors discuss three types of model: (i) purely empirical models, (ii) the purely physical or first principles models, and (iii) the semi-empirical models which combine elements of the first two.

TL;DR: In this article, the authors show that the polar vortex in northern winter is stronger and colder in the west than in the east years of the equatorial Quasi-Biennial Oscillation (QBO).

TL;DR: In this article, a new Umkehr algorithm for the estimation of the vertical ozone profile from observations of the umkehr effect of Gotz was described, which uses new ozone absorption coefficients, which result in a change in the scale of measurement, and their temperature dependence.

TL;DR: In this article, an ozonesonde capability has been established at Ascension Island, located downwind of the primary source region of ozone pollution, which likely results from the photochemical oxidation of emissions emanating from the widespread burning of savanna.

TL;DR: In this paper, an instrument system developed for the recording of large amplitude ELF (Extremely Low Frequency) atmospherics or "events" radiated by lightning in the band 5-50 Hz is described.

TL;DR: In this paper, an analysis of the long-term mean pressure-latitude seasonal distribution of tropospheric and lower stratospheric ozone for the four seasons covering, in part, over 20 years of ozonesonde data is presented.

TL;DR: In this paper, the 12 monthly mean values of noon-time ǫF 2 at Ahmedabad (23°N, 73°E) show a large hysteresis effect when plotted against sunspot number or against geomagnetic Ap.

TL;DR: In this paper, wind and tides from the MF radar near Tromso are compared with data from the SOUSY VHF radar near Andenes (69°N, 16°E) and from rocket chaff and falling sphere systems, both obtained during SINE (Summer in Northern Europe; 7 June-19 July 1987).

TL;DR: In this paper, the spatial and temporal distribution of spectral characteristics of the magnetospheric cusp and boundary layer were analyzed using ground riometer, magnetometer and ionosonde measurements.

TL;DR: A brief review of advances in our understanding of some physical processes related to the South Atlantic Magnetic Anomaly (SAMA) is intended to highlight specific issues on which further research is needed.

TL;DR: In this paper, the authors carried out radar observations at Aberystwyth (52.4°N, 4.1°W) during the period May-August 1990 to search for echoes analogous to the Polar Mesosphere Summer Echoes commonly observed at high latitudes.

TL;DR: In this article, it is shown that the dressed particle approach breaks down when the dust grain separation r d and the charge Z become large, and that the scattering cross-section then may be strongly enhanced.

TL;DR: In this article, the atmospheric circulation response to solar flares and geomagnetic disturbances is studied, and it is shown that solar flares cause an increase of the zonal circulation intensity in the latitudinal belt ρ = 45-65°, while geOMagnetic disturbances are associated with a decrease of the circulation intensity.

TL;DR: In this paper, the results of rocket measurements are compared with measurements of the radio wave absorption in the lower ionosphere performed at similar latitudes in central Europe, showing that while the night-time enhancement of absorption can be explained by increased electron density related to the measured increase of ion density as a consequence of enhanced penetration of high energy particles, the daytime increase of absorption needs to be explained mainly in terms of the observed increase of nitric oxide concentration.

TL;DR: In this paper, the authors show that solar radio noise could be a reasonably good substitute, better than sunspots, for predicting ǫoF2 values on time scales of one month, or more.

TL;DR: In this article, the three components of the F-region plasma drift at the magnetic equator are such that the North-South component corresponds to the meridional neutral air wind while the other two components represent the electrodynamic drift.

TL;DR: In this paper, the relationship between the strength of the applied field and the corresponding increase in electron temperature at different heights is investigated and a valid comparison of the predicted increases in temperature with the values observed accurate measurements must be made with a time resolution which matches the rapid variations in field strength.

TL;DR: In this paper, the effects of the quasibiennial oscillation (QBO) in the stratosphere on upward propagating semidiurnal tides were investigated and the results indicated that significant variability (5-20 m/s) in semidurnal winds in the mesosphere is attributable to the QBO of stratospheric mean winds and temperatures.

TL;DR: In this paper, the positive ion composition of the lower auroral E-region was probed by rocket-borne mass spectrometers in the altitude region from about 80 to 120km.

TL;DR: In this paper, small scale electron density perturbations were found to be excited near the reflection and upper hybrid resonance (UHR) points of an O-mode pump wave, which correlated well with a decrease of the intensity of stimulated electromagnetic emission (SEE).

TL;DR: The scientific objective of the ROSE (Rocket and Scatter Experiments) project is outlined together with a description of the rocket payload in this article, where the results from the in situ as well as from the ground-based experiments are discussed with respect to the E -region plasma instabilities which are investigated.

TL;DR: In this paper, the drying rate of paper towelling moistened by water was measured as a function of the strength of the electric field in which they were placed and the drying time increased monotonically with E, the associated drying time (in a typical experiment) decreasing by a factor of about 6 as E rose from 0 to 7 kV/cm.

TL;DR: The theory of spaced-antenna techniques for the measurement of aspect sensitivity of radar backscatter from the atmosphere is considered in this article, where correlation measurements made on the wave field can be used to determine the angular power spectrum of the returned energy in much the same way that aperturesynthesis techniques are used in radio astronomy.

TL;DR: In this paper, a high-resolution method is used to characterize homogeneous and stationary electromagnetic turbulence in space plasma by the field-energy distribution (FED) that specifies how the field energy is distributed with regards to the angular frequency ω and to the wave vector k.